39 results on '"Seung-Chan Park"'
Search Results
2. Effects of estrogen inhibition formula herbal mixture for danazol-induced precocious puberty in female rats: An experimental study with network pharmacology
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Seung Chan Park, Tuy An Trinh, Won-Yung Lee, Ji Yun Baek, Seungyong Lee, Kyuhee Choi, Jaewon Ha, Chang-Eop Kim, Ki Sung Kang, and Hye Lim Lee
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Herbal medicine ,Estrogen inhibition ,Hypothalamic-pituitary-gonads axis (HPGA) ,network pharmacology ,Puberty ,Miscellaneous systems and treatments ,RZ409.7-999 - Abstract
Background: This study aimed at determining the effect of the herbal mixture estrogen inhibition formula (EIF) and its possible mechanisms by precocious puberty animal models and network pharmacology-based analysis. Methods: Precocious puberty animal models were established by a single injection of 300 μg danazol, then female rats were administered EIF, vaginal openings were monitored, uterus and pituitary indices were determined. The levels of ALP, E2, LH, and FSH were measured using ELISA kits. Real-time PCR was performed to evaluate the mRNA expression of GnRH, UNC5C, and netrin-1 in hypothalamic tissues. We applied network pharmacological analysis to predict potential targets and pathways of EIF. Results: EIF delayed danazol-induced early vaginal opening. In the onset model, EIF reduced the increased levels of serum ALP, E2, LH, and FSH; as well as mRNA expressions of GnRH, Netrin-1, and UNC5C. Moreover, long-term administration of EIF not only diminished all impaired factors but also had no effect on the normal development of the animals. The gene set enrichment analysis showed that the targets of EIF are mainly associated with the GnRH signaling and ovarian steroidogenesis pathways. Conclusion: EIF could be used in preclinical research for the treatment of precocious puberty by the inhibition of HPGA pre-maturation.
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- 2021
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3. Herbal medicine (Jogyeongseongjang decoction) for precocious puberty girls: a retrospective study
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Soo Bo Shim, Kyu Hee Choi, Seung Yong Lee, Jae Jun Lee, Min Seok Bu, Ju Ah Lee, In Chul Jung, Yang Chun Park, Seung Chan Park, and Hye Lim Lee
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Miscellaneous systems and treatments ,RZ409.7-999 - Published
- 2020
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4. An increasing tendency of precocious puberty among Korean children from the perspective of COVID-19 pandemic effect
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Kyu Hee Choi and Seung Chan Park
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Pediatrics, Perinatology and Child Health - Abstract
IntroductionThis study was conducted to investigate changes and new trends over the past 6 years by analyzing the current status of precocious puberty (PP) treatment and treatment costs in Korea between 2016 and 2021.Materials and methodsAnnual and monthly number of patients diagnosed with PP from 2016 to 2021 were reviewed using the data from Healthcare Bigdata Hub. Annual medical insurance expenses for the treatment of PP were also reviewed. The data were compared by the gender of the patients.ResultsThe number of patients diagnosed with PP rose from 86,352 in 2016 to 166,645 in 2021, while medical expenses rose from KRW 64,111,689,000 in 2016 to KRW 134,642,100,000 in 2021. The percentage of male PP patients increased from 9.21% in 2016 to 19.55% in 2021.ConclusionIncreasing numbers of Korean patients diagnosed with PP. Consistent with the situation in other countries, the rapid increase in the number of cases since April 2020 appears to be a result of the COVID-19 pandemic. In Korea, this is considered a nationwide phenomenon. Also on the rise is the incidence of PP in males, which appears to be due to an increased awareness of the phenomenon. Further investigations are required to determine the possible causes in increasing prevalence of PP.
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- 2022
5. Effects of estrogen inhibition formula herbal mixture for danazol-induced precocious puberty in female rats: an experimental study with network pharmacology
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Seung Yong Lee, Ji Yun Baek, Kyuhee Choi, Seung Chan Park, Ki Sung Kang, Hye Lim Lee, Chang-Eop Kim, Jaewon Ha, Tuy An Trinh, and Won-Yung Lee
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medicine.medical_specialty ,medicine.drug_class ,0211 other engineering and technologies ,Uterus ,02 engineering and technology ,UNC5C ,03 medical and health sciences ,0302 clinical medicine ,Network pharmacology ,Internal medicine ,021105 building & construction ,medicine ,Precocious puberty ,network pharmacology ,Miscellaneous systems and treatments ,Gene ,Hypothalamic-pituitary-gonads axis (HPGA) ,Danazol ,Messenger RNA ,business.industry ,Puberty ,RZ409.7-999 ,medicine.disease ,musculoskeletal system ,Estrogen inhibition ,030205 complementary & alternative medicine ,medicine.anatomical_structure ,Endocrinology ,Complementary and alternative medicine ,Estrogen ,Original Article ,Herbal medicine ,business ,medicine.drug - Abstract
Background This study aimed at determining the effect of the herbal mixture estrogen inhibition formula (EIF) and its possible mechanisms by precocious puberty animal models and network pharmacology-based analysis. Methods Precocious puberty animal models were established by a single injection of 300 μg danazol, then female rats were administered EIF, vaginal openings were monitored, uterus and pituitary indices were determined. The levels of ALP, E2, LH, and FSH were measured using ELISA kits. Real-time PCR was performed to evaluate the mRNA expression of GnRH, UNC5C, and netrin-1 in hypothalamic tissues. We applied network pharmacological analysis to predict potential targets and pathways of EIF. Results EIF delayed danazol-induced early vaginal opening. In the onset model, EIF reduced the increased levels of serum ALP, E2, LH, and FSH; as well as mRNA expressions of GnRH, Netrin-1, and UNC5C. Moreover, long-term administration of EIF not only diminished all impaired factors but also had no effect on the normal development of the animals. The gene set enrichment analysis showed that the targets of EIF are mainly associated with the GnRH signaling and ovarian steroidogenesis pathways. Conclusion EIF could be used in preclinical research for the treatment of precocious puberty by the inhibition of HPGA pre-maturation.
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- 2020
6. Comparison of the demographic and wound characteristics of non-suicidal and suicidal self-wrist cutting injuries
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Yoo Chang Kim, Yoon Joo Cho, Yoo Joon Sur, Ho Youn Park, and Seung Chan Park
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Male ,Suicide, Attempted ,Treatment Refusal ,0302 clinical medicine ,Psychiatric history ,wrist cutting syndrome ,Medicine ,Outpatient clinic ,030212 general & internal medicine ,Young adult ,Suicidal ideation ,Aged, 80 and over ,Medical record ,Mental Disorders ,General Medicine ,Middle Aged ,Wrist Injuries ,Hospitalization ,030220 oncology & carcinogenesis ,Female ,medicine.symptom ,Emergency Service, Hospital ,Research Article ,Adult ,Mental Health Services ,suicide attempt ,medicine.medical_specialty ,Adolescent ,Observational Study ,Wounds, Stab ,03 medical and health sciences ,Young Adult ,Age Distribution ,Internal medicine ,Republic of Korea ,Humans ,Interpersonal Relations ,Sex Distribution ,Aged ,Retrospective Studies ,non-suicidal self-injury ,Suicide attempt ,business.industry ,Retrospective cohort study ,Emergency department ,self-injurious behavior ,Patient Compliance ,business ,Stress, Psychological ,wrist laceration - Abstract
Patients who commit self-wrist cutting injuries (SWCIs) are a heterogeneous group composed of patients with non-suicidal self-injury (NSSI) and suicide attempt (SA). The purpose of this study was to compare the demographic features and wound characteristics of patients with NSSI and SA. A retrospective review of 300 patients who visited the emergency department (ED) for treatment of SWCIs between January 2011 and December 2015 was performed. Data collected from the electronic medical records included age, sex, the reason for SWCIs, presence of suicidal ideation, concomitant intoxication with alcohol or drugs, past psychiatric history, whether or not the patient received psychiatric counseling at the ED, the principal psychiatric diagnosis, the number and severity of external wounds, and subsequent follow-up at the psychiatric or hand surgery outpatient department (OPD). The patients were divided into the NSSI and SA groups according to the presence of suicidal ideation and other variables were compared between the two groups. There were 138 NSSI patients and 162 SA patients. The NSSI group was younger (33.9 years vs 40.9 years, P
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- 2020
7. Herbal medicine (Jogyeongseongjang decoction) for precocious puberty girls: a retrospective study
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Jae-Jun Lee, Seung Yong Lee, Hye Lim Lee, Ju Ah Lee, Yang Chun Park, In Chul Jung, Soo Bo Shim, Kyu Hee Choi, Min Seok Bu, and Seung Chan Park
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Pediatrics ,medicine.medical_specialty ,business.industry ,MEDLINE ,Decoction ,Retrospective cohort study ,medicine.disease ,lcsh:RZ409.7-999 ,Complementary and alternative medicine ,medicine ,Precocious puberty ,business ,lcsh:Miscellaneous systems and treatments ,Letter to the Editor - Published
- 2020
8. Preventive Effect and Safety of a Follicle Stimulating Hormone Inhibitory Formulation Containing a Mixture of Coicis Semen and Artemisia capillaris for Precocious Puberty: A Preliminary Experimental Study Using Female Rats
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Jihong Oh, Chang-Eop Kim, Hwa-Seung Yoo, Tuy An Trinh, Hye Lim Lee, Seung Chan Park, and Ki Sung Kang
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0301 basic medicine ,medicine.medical_specialty ,030219 obstetrics & reproductive medicine ,Endocrine disease ,Article Subject ,Secondary sex characteristic ,lcsh:Other systems of medicine ,Biology ,lcsh:RZ201-999 ,medicine.disease ,Short stature ,03 medical and health sciences ,Follicle-stimulating hormone ,030104 developmental biology ,0302 clinical medicine ,Endocrinology ,Complementary and alternative medicine ,In vivo ,Oral administration ,Internal medicine ,medicine ,Precocious puberty ,Lipolysis ,medicine.symptom - Abstract
Background. Precocious puberty is a common endocrine disease in children. Inappropriate activation of hypothalamic–pituitary–gonadal axis leads to the development of secondary sexual characteristics at an earlier age than normal children and causes short stature in adulthood. Objectives. The aim of this study is to evaluate the preventive effects of a herbal formulation containing a mixture of Coicis Semen and Artemisia capillaris (hEIF extract) on precocious puberty. Methods. The preventive effect of hEIF extract on precocious puberty in rats was evaluated by measuring blood component after 3 weeks of treatment via oral administration. Network pharmacological analyses were performed to predict the bioactive components of hEIF extract. Results. In vivo studies showed that hEIF extract significantly reduced follicle stimulating hormone (FSH) levels. After treatment with 200 mg/kg of hEIF extract, the FSH level was 5.33±1.10 ng/mL, whereas the FSH level in the vehicle group was 46.73±0.80 ng/mL. Moreover, the use of hEIF extract did not stimulate body growth and bone accretion in rats. The network pharmacological analysis led to the identification of multiple targets of hEIF extract related to lipolysis and the female sex hormone-related pathways. Conclusion. hEIF extract can be used as an FSH inhibitor for the treatment of precocious puberty.
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- 2017
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9. An Increase of Patients Diagnosed as Precocious Puberty among Korean Children from 2010 to 2015
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Seung Chan Park and Kyu Hee Choi
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Pediatrics ,medicine.medical_specialty ,Leuprorelin ,business.industry ,medicine ,Precocious puberty ,business ,medicine.disease ,medicine.drug - Published
- 2016
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10. Impact of dialysis modality on technique survival in end-stage renal disease patients
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Ji-Young Choi, Sang Un Kim, Seung Chan Park, Jeong-Hoon Lim, Chan-Duck Kim, O. Kwon, Young-Jae Park, Jang-Hee Cho, Yong-Lim Kim, Sun-Hee Park, Kyung Hee Lee, Kyung-hoon Kim, Hee-Yeon Jung, and Jong-Hak Lee
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Adult ,Male ,medicine.medical_specialty ,Time Factors ,Survival ,medicine.medical_treatment ,Peritoneal dialysis ,Nutritional Status ,End stage renal disease ,Body Mass Index ,Renal Dialysis ,Risk Factors ,Internal medicine ,Republic of Korea ,medicine ,Humans ,Prospective Studies ,Risk factor ,Prospective cohort study ,Survival rate ,Dialysis ,Aged ,business.industry ,Hazard ratio ,Diabetes ,Middle Aged ,Surgery ,Treatment Outcome ,Nephrology ,Hemodialysis ,Kidney Failure, Chronic ,Original Article ,business - Abstract
Background/aims This study analyzed the risk factors for technique survival in dialysis patients and compared technique survival rates between hemodialysis (HD) and peritoneal dialysis (PD) in a prospective cohort of Korean patients. Methods A total of 1,042 patients undergoing dialysis from September 2008 to June 2011 were analyzed. The dialysis modality was defined as that used 90 days after commencing dialysis. Technique survival was compared between the two dialysis modalities, and the predictive risk factors were evaluated. Results The dialysis modality was an independent risk factor predictive of technique survival. PD had a higher risk for technique failure than HD (hazard ratio [HR], 10.8; 95% confidence interval [CI], 1.9 to 62.0; p = 0.008) during a median follow-up of 11.0 months. In the PD group, a high body mass index (BMI) was an independent risk factor for technique failure (HR, 1.3; 95% CI, 1.0 to 1.8; p = 0.036). Peritonitis was the most common cause of PD technique failure. The difference in technique survival between PD and HD was more prominent in diabetic patients with a good nutritional status and in non-diabetic patients with a poor nutritional status. Conclusions In a prospective cohort of Korean patients with end-stage renal disease, PD was associated with a higher risk of technique failure than HD. Diabetic patients with a good nutritional status and non-diabetic patients with a poor nutritional status, as well as patients with a higher BMI, had an inferior technique survival rate with PD compared to HD.
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- 2015
11. Low-pathogenic Pinewood Nematode Found in Dead Trees and Resistance of Pines Induced by Its Pre-inoculation
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Dong Soo Kim, Seung-Chan Park, and Yil-Sung Moon
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Horticulture ,Resistance (ecology) ,Inoculation ,Pinewood nematode ,Botany ,Dead tree ,Biology ,Low pathogenic - Abstract
Pinewood nematode (PWN: Bursaphelenchus xylophilus ) is known to kill pine tree species that are indigenous to countrieswhere the pest was inadvertently imported, but some cultures from the extraction of dead pines do not damage trees. Experiments wer econducted to examine the effect of pre-inoculation of these low-pathogenic pinewood nematode on resistance of pine trees agains t the pest species. The pre-inoculated pine saplings showed induced resistance which lasted for a year, and repeated inoculation of these low-pathogenic nematodes enhanced tree resistance. All nematode samples extracted from dying or dead pines that had been killed notmore than three months before the extraction were pathogenic, and most of those extracted from pines that had been killed 2-3 years before were low-pathogenic. When inoculated in pine saplings, number of low-pathogenic nematodes settled, as studied two days af ter inoculation, was not different from that of pathogenic ones. However, as studied after 30 days of inoculation, rate of reproduction in low-pathogenic nematodes was far lower than that of pathogenic nematodes. The rate of reproduction of several nematode isolates growing on fungal mat media of Botrytis cinerea varied, but three of four low-pathogenic isolates showed same level of reproduction rate sas pathogenic ones.Key words: Pinewood nematode, Bursaphelenchus xylophilus, Low-pathogenic, Pre-inoculation, Induced resistance초 록: 소나무재선충은 현재까지 도입된 국가의 토착수종인 소나무류를 모두 치사시키는 것으로 알려져 있으나 , 고사목으로부터 추출․배양된 계통 중에는 소나무에 피해를 주지 않는 계통이 존재한다. 이러한 저병원성 계통 선충의 사전접종이 고병원성 소나무재선충에 대한 소나무의 저항성에 미치는 영향을 조사하기 위하여 연구가 수행되었다. 치수에 저병원성 소나무재선충을 선접종한 결과, 선접종에 의하여 소나무재선충에 대한 저항력이 유도되었다. 그 유도저항성은 1년 후까지 유지되었으며, 저병원성 선충의 반복 감염은 보다 저항성 유도 효과가 큰 것으로 나타났다 . 소나무재선충에 의하여 고사한 후 경과기간이 3개월 이하인 피해목 및 피해진행목에서 분리된 선충은 모두 고병원성이었으며, 고사 후 2-3년이 경과한 벌채목에서 분리된 선충 5계통 중 4계통은 저병원성이었다. 저병원성 선충이 소나무 치수에 인공접종 되었을 때 초기 정착률은 고병원성 선충과 차이가 없었으나, 접종 30일 후에 수목내의 부위별 개체수를 조사한바 저병원성 선충의 증식률은 고병원성보다 현저히 낮았다 . 저병원성 선충의 잿빛곰팡이병 균사배지에서의 선충증식 속도는 계통에 따라 차이가 있었으며, 증식속도가 빠른 계통은 대체로 고병원성 선충의 증식속도와 차이가 없었다.검색어: 소나무재선충, 저병원성, 선접종, 유도저항성*Corresponding author: pscpine@hanmail.netReceived February 25 2014; Revised March 10 2014Accepted March 31 2014
- Published
- 2014
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12. A Review of Diagnostic Methods on Neurologic Symptoms by Non-organic Causes: A Case of a Patient
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Seung Chan Park, So-yeon Kim, Jin Woo Hong, In Lee, Jung Hwa Lim, Jung Nam Kwon, Seong Ha Park, Chang Woo Han, Min Kyoung Cho, Jun-Yong Choi, and Do-hyung Kim
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Sensory disturbance ,medicine.medical_specialty ,Diagnostic methods ,medicine.diagnostic_test ,medicine ,Diagnostic test ,Neurological examination ,Intensive care medicine ,Psychology ,Psychiatry - Abstract
Objectives: The objective of this study is to review the diagnostic methods of neurologic symptoms by non-organic causes. Methods: We experienced a case of a motor and sensory disturbance patient without abnormal findings in the diagnostic tests. Using this process, we became aware that it is important to remember some of the methods when treating patients who are suspicious of neurologic symptoms by non-organic causes. Results: First, we should perform a variety of diagnostic tests to exclude the organic causes. Second, we should persistently observe a consistency of the patient`s symptoms and attitude. Finally, we should perform a neurological examination in order to acquire the objective physical findings. Conclusions: Because there are limitations in the methods above, we have to be aware of making a mistake regarding the disability by organic causes as that by non-organic causes.
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- 2014
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13. Radiologic criteria to predict injury of the transverse atlantal ligament in unilateral sagittal split fractures of the C1 lateral mass
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Kyung-Jin Song, Jong-Beom Park, Dong-Gune Chang, Whoan Jeang Kim, Woo-Kie Min, Heui-Jeon Park, and Seung Chan Park
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Adult ,Male ,Lateral mass ,Observational Study ,Joint axis ,03 medical and health sciences ,0302 clinical medicine ,Clivus ,medicine ,Humans ,030212 general & internal medicine ,Cervical Atlas ,Aged ,Retrospective Studies ,unilateral sagittal split fracture ,medicine.diagnostic_test ,urogenital system ,business.industry ,Magnetic resonance imaging ,transverse atlantal ligament ,General Medicine ,Middle Aged ,Magnetic Resonance Imaging ,Sagittal plane ,Transverse atlantal ligament ,medicine.anatomical_structure ,C1 lateral mass ,030220 oncology & carcinogenesis ,Ligaments, Articular ,Spinal Fractures ,Female ,business ,Nuclear medicine ,radiologic criteria ,Research Article - Abstract
Unilateral sagittal split fracture (USSF) of the C1 lateral mass (LM) has been recently recognized as a rare variant of C1 atlas fracture. To date, there has been no study to investigate whether radiologic criteria can be applied to determine the presence or absence of transverse atlantal ligament (TAL) injury in USSF of the C1 LM. Twenty six consecutive cases of USSF of the C1 LM were included in this study. According to Dickman classification, 16 cases were TAL injury, and 10 cases were TAL intact. Radiologic parameters were measured and compared between the 2 groups. Total LM displacement (LMD) of the 2 sides (5.9 ± 2.0 mm vs 1.2 ± 2.0 mm), unilateral LMD of the fracture side (4.3 ± 1.2 mm vs 1.0 ± 1.1 mm), atlanto-dental interval (ADI) (2.0 ± 0.9 mm vs 1.5 ± 0.4 mm), and fracture gap (6.9 ± 2.7 mm vs 2.1 ± 1.1 mm) were statistically higher in the TAL injury group than the TAL intact group. However, basion-dental interval, clivus canal angle, and atlanto-occipital joint axis angle were not different between the 2 groups. Total LMD and unilateral LMD positively correlated with ADI and fracture gap. The incidence of fracture gap larger than 7 mm was statistically higher in the TAL injury group than the TAL intact group (81% vs 30%). In conclusion, total LMD > 5.9 mm or unilateral LMD > 4.3 mm suggests the presence of TAL injury in USSF of the C1 LM. The possibility of diagnostic error for TAL injury can be further reduced in USSF of the C1 LM by considering the fracture gap larger than 7 mm.
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- 2019
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14. Comparison of the demographic and wound characteristics of non-suicidal and suicidal self-wrist cutting injuries.
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Ho Youn Park, Yoo Chang Kim, Seung Chan Park, Yoon Joo Cho, Yoo Joon Sur, Park, Ho Youn, Kim, Yoo Chang, Park, Seung Chan, Cho, Yoon Joo, and Sur, Yoo Joon
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- 2020
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15. Manipulation of Summer Diapause by Chilling in Matsucoccus thunbergianae (Hemiptera: Coccoidea: Margarodidae)
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Seung-Chan Park, An-Jin Wi, and Jong-Hee Lee
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Horticulture ,Pinus thunbergii ,biology ,Botany ,Instar ,Diapause ,Nymph ,biology.organism_classification ,Moulting ,Hemiptera ,Degree (temperature) ,Margarodidae - Abstract
A set of experiments were conducted to determine the zero temperature and total effective temperature for the summer diapause and post-diapause development of Matsucoccus thunbergianae Miller et Park (Hemiptera: Margarodidae) which infests the Japanese black pine, Pinus thunbergii. The diapausing first instar nymphs were kept in cool storage during three separate times, each starting from May 4th, June 19th, and August 15th of 2002. Cool storage temperatures were 2.5, 5.0, 7.5, 10.0, 12.5 and . The nymphs were chilled for 10, 20, 30 or 40 days in the first two sets of experiments. In the third experiment, nymphs were chilled for 3, 6, 9 or 12 days. Molting into the second instar nymphs was examined every 10 days, starting at 20 days after taken out from the cool storage. Optimum temperature range of the diapause development was between 7.5 and , where diapause development was completed in 40, 20, and 6 days by the insects chilled from May 4th, June 19th and August 15th, respectively. Comparing the three sets of experiments with different chilling periods, zero temperature for diapause development was calculated as . Effective temperature for diapause development was 964 degree days, and it was estimated that nymphs completed their diapause development by September 8th in nature. Under natural temperature conditions >50% eclosion into the second instar occurred on November 9th. Zero temperature for post-diapause development was , and total effective temperature for post-diapause development until the molt into the second instar was 391 degree days.
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- 2013
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16. Approximate Modeling of Doctor Blade Contact Pressure for Realization of Uniform Image Quality
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Ha-Young Choi, Seung Chan Park, and Jongsoo Lee
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Optimal design ,Cartridge ,Engineering ,Blade (geometry) ,Image quality ,business.industry ,Design of experiments ,Mechanical engineering ,Structural engineering ,Response surface methodology ,business ,Durability ,Finite element method - Abstract
The doctor blade is equipped in a toner cartridge and is a device to maintain the uniform thickness of a toner by controlling the pressure on the developing roller. The contact pressure between the developing roller and the doctor blade is one of the significant factors for image quality and durability of toner cartridge. The purpose of this study is to develop approximation model in order to minimize the time and cost which are needed much required in making optimal design of the doctor blade. Central composite design was used for the design of experiment and response surface design was used for approximation. The data for contact pressure were acquired through finite element analysis and data of image density and toner weight were acquired through experiment. The approximation model developed in this study has presented very high fitness.
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- 2013
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17. A 5.8-GHz High-Frequency Resolution Digitally Controlled Oscillator Using the Difference Between Inversion and Accumulation Mode Capacitance of pMOS Varactors
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Hong-Joo Song, Hyung Joun Yoo, Sang-Sun Yoo, Jeong-Ho Park, Seung-Chan Park, and Yong-Chang Choi
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Radiation ,Materials science ,business.industry ,Condensed Matter Physics ,Capacitance ,PMOS logic ,Phase-locked loop ,Voltage-controlled oscillator ,CMOS ,Phase noise ,Electronic engineering ,Optoelectronics ,Digitally controlled oscillator ,Electrical and Electronic Engineering ,business ,Varicap - Abstract
This paper proposes an oppositely coupled varactor pair and reports the measured results for applying to a test digitally controlled oscillator (DCO). The pair exploits the differences between the accumulation region capacitance and inversion region capacitance of pMOS varactors. The novel varactor pairs provide much smaller switchable capacitances than those of other approaches, and hence, the test DCO for verifying the property of the pair achieves the high-frequency resolution. The pairs and test DCO are implemented in a 0.18-μm CMOS process. The switchable discrete capacitance of 32 aF is obtained by using the novel varactor pairs, and the test DCO has a frequency resolution of about 110 kHz at 5.8 GHz. Furthermore, ΔC of 4-aF and 14-kHz frequency resolution can be obtained through the dithering processes. The test DCO achieves a low phase noise of -117.6 dBc/Hz at 1-MHz offset from 5.8 GHz.
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- 2011
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18. The Moving Average Ratio and Momentum
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Seung-Chan Park
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Economics and Econometrics ,Momentum (technical analysis) ,Moving average ,Statistics ,Economics ,Anchoring ,Statistical physics ,Behavioral theory ,Moving average crossover ,Momentum profits ,health care economics and organizations ,Finance - Abstract
I show the ratio of the short-term moving average to the long-term moving average (moving average ratio, MAR) has significant predictive power for future returns. The MAR combined with nearness to the 52-week high explains most of the intermediate-term momentum profits. This suggests that an anchoring bias, in which investors use moving averages or the 52-week high as reference points for estimating fundamental values, is the primary source of momentum effects. Momentum caused by the anchoring bias do not disappear in the long-run even when there are return reversals, confirming that intermediate-term momentum and long-term reversals are separate phenomena.
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- 2010
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19. South Korean Chaebols and Value-Based Management
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Sviatoslav A. Moskalev and Seung Chan Park
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Economics and Econometrics ,Guiding Principles ,Corporate governance ,Context (language use) ,General Business, Management and Accounting ,Empire-building ,Market economy ,Arts and Humanities (miscellaneous) ,Shareholder ,Expropriation ,Financial crisis ,Economics ,Business and International Management ,Economic system ,Business ethics ,Law - Abstract
South Korean industrial conglomerates (chaebols) are discussed in the context of value-based management (VBM). Recent economics and finance literature on the diversion of corporate resources from the firm to the controlling shareholders (tunneling), for which chaebols are notoriously known, is discussed. Chaebols have engaged in empire building and expropriation of minority shareholders, distorting the process of efficient resource allocation in South Korea, and became the root cause of the 1997 financial crisis. We argue that the 1997 crisis should be viewed as a consequence of chaebols’ systematic deviation from the guiding principles of VBM. We use tunneling within chaebols as an example of the need to directly address prohibition of the expropriation of minority shareholders as a primary postulate of VBM. We argue that VBM should require that the value generated by the firm not be expropriated from minorities, or any stakeholders, by dominant shareholders. We also examine moral and ethical considerations and present explanations as to why the unethical practice of tunneling has been tolerated by the South Korean public. We show that public opinion on tunneling is changing and that the treatment of minority shareholders by chaebols’ controlling families is becoming increasingly unacceptable to South Koreans.
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- 2009
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20. pp한국 하이테크 기업의 대중국 기술이전 경로선택에 관한 실증연구- 라이센싱과 독자투자 경로선택을 중심으로
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박승찬 ( Seung Chan Park )
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Business - Published
- 2008
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21. Effect of contact resistance between side-bar and secondary conductors in a linear induction motor with a cage-type secondary
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Seung-Chan Park and Byung-Taek Kim
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Electric motor ,Materials science ,Normal force ,Contact resistance ,Electronic, Optical and Magnetic Materials ,law.invention ,law ,Linear induction motor ,Eddy current ,Equivalent circuit ,Electrical and Electronic Engineering ,Composite material ,Electrical conductor ,Induction motor - Abstract
A linear induction motor (LIM) with a cage-type secondary has contact resistances between side-bars and secondary conductors due to its own manufacturing process of welding. The finite-element analysis considering the equivalent circuit of the secondary winding is carried out to present the effect of the contact resistance in the LIM. As a result, thrust, normal force, the primary phase current, and the secondary conductor currents of the motor are analyzed for the various contact resistances.
- Published
- 2003
- Full Text
- View/download PDF
22. Detection of Carbamate Insecticides in Fruit and Vegetable Samples with an Acetylcholinesterase Inhibition-Based Bioassay
- Author
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Seung-Chan Park, Mi Ra Kim, Chang Joo Lee, In Seon Kim, Jae-Han Shim, and Li Tai Jin
- Subjects
chemistry.chemical_classification ,Carboxylic Ester Hydrolases ,Carbamate ,Chromatography ,Health, Toxicology and Mutagenesis ,medicine.medical_treatment ,Pesticide ,Acetylcholinesterase ,chemistry.chemical_compound ,Carbamate insecticide ,Enzyme ,chemistry ,Insect Science ,medicine ,Bioassay ,Organic chemistry - Published
- 2003
- Full Text
- View/download PDF
23. Novel topology of unequal air gap in a single-phase brushless DC motor
- Author
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Young-Sun Jin, Seung-Chan Park, Byoung-Yull Yang, and Byung-il Kwon
- Subjects
Machine theory ,Computer science ,Cogging torque ,Torque ,Electrical and Electronic Engineering ,Single phase ,Topology ,Air gap (plumbing) ,Magnetostatics ,DC motor ,Finite element method ,Electronic, Optical and Magnetic Materials - Abstract
Most single-phase brushless DC (BLDC) motors have unequal air gaps to eliminate the dead point where the developed torque value is zero. These unequal air gaps deteriorate the motor characteristics in cogging torque. Thus in this paper a new topology of the unequal air gaps is proposed to solve this problem. As a result, it is proved by the finite element analysis and experimental results that the proposed air gap topology is very effective in reducing the cogging torque.
- Published
- 2001
- Full Text
- View/download PDF
24. Analysis for dynamic characteristics of a single-sided linear induction motor having joints in the secondary conductor and back-iron
- Author
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Seung Chan Park, Kyung Il Woo, Sol Kim, and Byung Il Kwon
- Subjects
Physics ,Electric motor ,Mechanics ,Linear motor ,Finite element method ,Electronic, Optical and Magnetic Materials ,law.invention ,Conductor ,law ,Linear induction motor ,Eddy current ,Electrical and Electronic Engineering ,Electrical conductor ,Induction motor - Abstract
In this paper, we discuss the analysis for the dynamic characteristics of a single-sided linear induction motor (SLIM) having the joints in the secondary conductor and the back-iron. The time-stepping finite element method and the moving mesh techniques are used for the simulation. The gradients of the electric scalar potential in the jointed secondary conductors and back-irons are defined for the eddy current analysis. The simulation results show that the junction between the secondary conductors creates a discontinuity of the eddy current and causes fluctuations of the thrust and the normal force.
- Published
- 2000
- Full Text
- View/download PDF
25. Finite element analysis for dynamic characteristics of an inverter-fed PMLSM by a new moving mesh technique
- Author
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Byung Il Kwon, Kyung Il Woo, Seung Chan Park, and Duck-Jin Kim
- Subjects
Physics ,Electric motor ,Computer simulation ,business.industry ,Structural engineering ,Linear motor ,Finite element method ,Electronic, Optical and Magnetic Materials ,law.invention ,law ,Mesh generation ,Magnet ,Eddy current ,Electrical and Electronic Engineering ,business ,Synchronous motor - Abstract
This paper presents the finite element analysis for the dynamic characteristics of an inverter-fed permanent magnet linear synchronous motor (PMLSM) having the conductive sheet secondary. The time-stepping finite element method and the moving mesh technique are used for the simulation. The eddy currents in the secondary aluminum sheet and solid back-iron are taken into account in the electromagnetic field analysis.
- Published
- 2000
- Full Text
- View/download PDF
26. Influence on brushless DC motor performance due to unsymmetric magnetization distribution in permanent magnet
- Author
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Tae-Ho Yoon, Sung Hong Won, Byung-il Kwon, Hee-Soo Yoon, and Seung-Chan Park
- Subjects
Electric motor ,Materials science ,Rotor (electric) ,Cogging torque ,AC motor ,DC motor ,Electronic, Optical and Magnetic Materials ,law.invention ,Quantitative Biology::Subcellular Processes ,Nuclear magnetic resonance ,Control theory ,law ,Magnet ,Torque ,Torque ripple ,Electrical and Electronic Engineering - Abstract
The real brushless DC motor has different permanent magnet pole magnetization levels due to the influence of the magnetizer geometry. Therefore, this paper discusses the influence of change in the magnetic parameter on brushless DC motor performances. As a result, the unbalanced magnetic force acting on the rotor, cogging torque and torque ripple are examined for spindle motor with unsymmetric magnetization distribution.
- Published
- 2000
- Full Text
- View/download PDF
27. Analysis of exterior-rotor BLDC motor considering the eddy current effect in the rotor steel shell
- Author
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Byung-il Kwon, Sung Hong Won, Young-Gyu Kang, Seung-Chan Park, and Hee-Soo Yoon
- Subjects
Electric motor ,Physics ,Squirrel-cage rotor ,Rotor (electric) ,Shell (structure) ,Mechanics ,AC motor ,DC motor ,Finite element method ,Electronic, Optical and Magnetic Materials ,law.invention ,Quantitative Biology::Subcellular Processes ,law ,Eddy current ,Electrical and Electronic Engineering - Abstract
This paper describes the effect of eddy currents generated in the rotor steel shell of an exterior-rotor type permanent magnet brushless DC motor of which the rotor is revolving at a high speed. A two dimensional time-stepped finite element method is used to analyze the electromagnetic field and compute motor performance. The conductivity of the rotor steel shell is modified to consider the transverse edge effect. As a result, the effect of eddy currents is shown by comparing the analysis results between when the proposed method is used and when the method it is not.
- Published
- 1999
- Full Text
- View/download PDF
28. Analysis of axially non-uniform loss distribution in 3-phase induction motor considering skew effect
- Author
-
Cha-Seung Jun, Seung-Chan Park, Byung-Il Kown, and Byung-Taek Kim
- Subjects
Electric motor ,Physics ,Rotor (electric) ,Squirrel-cage rotor ,Skew ,Mechanics ,Finite element method ,Magnetic flux ,Electronic, Optical and Magnetic Materials ,law.invention ,law ,Electrical and Electronic Engineering ,Axial symmetry ,Induction motor - Abstract
This paper discusses the phenomena of the axially nonuniform distribution of magnetic flux densities and losses in a three-phase squirrel cage induction motor of which the rotor bars are skewed. A 2-D complex finite element method, taking account of the effects of the skewed rotor bars, is utilized for the analysis of characteristics such as copper and iron losses and the loss distributions are examined. The summing up values of nonuniform losses resulted from the finite element analysis are compared with measurements.
- Published
- 1999
- Full Text
- View/download PDF
29. Analysis of radial force as a source of vibration in an induction motor with skewed slots
- Author
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B.T. Kim, Seung-Chan Park, Byung-il Kwon, J.H. Chang, Jung-Pyo Hong, and D.H. Im
- Subjects
Electromagnetic field ,Physics ,Coupling ,Stator ,Skew ,Mechanics ,Physics::Classical Physics ,Finite element method ,Electronic, Optical and Magnetic Materials ,law.invention ,Quantitative Biology::Subcellular Processes ,Vibration ,law ,Harmonics ,Electrical and Electronic Engineering ,Induction motor - Abstract
This paper presents a method to analyze radial force densities acting on each stator tooth of an induction motor with skewed slots. A two-dimensional finite element method is used for electromagnetic field analysis of an induction motor, and skew effects are considered by coupling several disks cut by planes perpendicular to the shaft. Radial force densities as a source of vibration are calculated along the surface elements of each stator tooth and its time harmonics are examined by discrete Fourier decomposition.
- Published
- 1997
- Full Text
- View/download PDF
30. Design of single-sided linear induction motor using the finite element method and SUMT
- Author
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Seung-Chan Park, D.H. Im, and Jee-Won Im
- Subjects
Electric motor ,Control theory ,Linear induction motor ,Constant current ,ComputerApplications_COMPUTERSINOTHERSYSTEMS ,Thrust ,Minification ,Electrical and Electronic Engineering ,Linear motor ,Finite element method ,Induction motor ,Electronic, Optical and Magnetic Materials ,Mathematics - Abstract
The optimization of the design variables of a single-sided linear induction motor (SLIM) using the finite-element method (FEM) and the sequential unconstrained minimization technique (SUMT) is presented. Thrust is taken as an objective function in order to maximize thrust under a constant current drive, and seven independent design variables and nine constraints are chosen. As a result, pole pitch/airgap and pole pitch/aluminum depth for the best design are determined. Thrust is increased by 30% under a constant current of 12 A, so that the input current can be reduced to 10.5 A for necessary starting thrust because thrust is proportional to I/sup 2/. >
- Published
- 1993
- Full Text
- View/download PDF
31. The 52-Week High And The January Effect
- Author
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Seung-Chan Park and Sviatoslav A. Moskalev
- Subjects
Incentive ,Window dressing ,Financial economics ,Reference price ,Predictive power ,Economics ,January effect - Abstract
The predictive power of past returns for January reversal is compared with that of the nearness of current prices to the 52-week high. When compared jointly, past returns lose their forecasting power for January returns and the nearness of current prices to the 52-week high assumes the dominant role in explaining the January reversal. This suggests that tax-loss selling is not the primary factor explaining the January effect. A behavioral explanation consistent with the window-dressing argument is proposed in that the 52-week high acts as an “anchor,” a highly visible reference price to fund holders, increasing fund managers’ incentives to window-dress by temporarily adding (removing) stocks that are perceived by fund holders as good (bad) investments, based on the nearness of these stocks’ current prices to the 52-week high.
- Published
- 2010
- Full Text
- View/download PDF
32. Induction of apoptosis in human lung carcinoma cells by the water extract of Panax notoginseng is associated with the activation of caspase-3 through downregulation of Akt
- Author
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Wun-Jae Kim, Yeon-Weol Lee, Cheol Park, Hwa-Seung Yoo, Seung Chan Park, Yung Hyun Choi, Chong-Kwan Cho, and Gi-Young Kim
- Subjects
Cancer Research ,Programmed cell death ,Lung Neoplasms ,Cell Survival ,Morpholines ,Down-Regulation ,Apoptosis ,Caspase 3 ,Cysteine Proteinase Inhibitors ,Biology ,Downregulation and upregulation ,Cell Line, Tumor ,Humans ,Panax notoginseng ,Phosphorylation ,Protein Kinase Inhibitors ,Protein kinase B ,PI3K/AKT/mTOR pathway ,Cell Proliferation ,bcl-2-Associated X Protein ,Membrane Potential, Mitochondrial ,Dose-Response Relationship, Drug ,Akt/PKB signaling pathway ,biology.organism_classification ,Antineoplastic Agents, Phytogenic ,Mitochondria ,Enzyme Activation ,Proto-Oncogene Proteins c-bcl-2 ,Oncology ,Chromones ,Cancer research ,Poly(ADP-ribose) Polymerases ,Oligopeptides ,Proto-Oncogene Proteins c-akt ,Drugs, Chinese Herbal ,Signal Transduction - Abstract
The root of Panax notoginseng is highly valued and commonly used in Oriental medicine. Although recent experimental data have revealed the proapoptotic potency of P. notoginseng extracts, the underlying molecular mechanisms of this apoptotic activity have not yet been studied in detail. In the present study, the effects of the water extract of P. notoginseng (WEPN) on the growth of human lung carcinoma cells were investigated. It was found that the exposure of A549 and NIC-H460 cells to WEPN resulted in growth inhibition and the induction of apoptosis in a dose-dependent manner. The WEPN treatment induced the upregulation of pro-apoptotic Bax, downregulation of anti-apoptotic Bcl-2 expression and loss of mitochondrial membrane potential (MMP), which was associated with the proteolytic activation of caspases and the concomitant degradation of poly(ADP ribose) polymerase (PARP) protein. However, the caspase-3-specific inhibitor z-DEVD-fmk blocked PARP degradation and increased the survival rate of WEPN-treated cells. Moreover, the activity of Akt was downregulated in WEPN-treated cells and the phosphatidylinositol-3 kinase (PI3K)/Akt inhibitor LY294002 sensitized the cells to WEPN-induced apoptosis through enhancing the activation of caspase-3 and loss of MMP. The results indicated that the major regulators of WEPN-induced apoptosis in human lung carcinoma cells are the Bcl-2 family and caspase-3, which are associated with mitochondrial dysfunction and dephosphorylation of the Akt signaling pathway.
- Published
- 2009
- Full Text
- View/download PDF
33. Regulation of resin acid synthesis in Pinus densiflora by differential transcription of genes encoding multiple 1-deoxy-D-xylulose 5-phosphate synthase and 1-hydroxy-2-methyl-2-(E)-butenyl 4-diphosphate reductase genes
- Author
-
Soo-Un Kim, Tomohisa Kuzuyama, Sang-Chul Shin, Sangmin Kim, Yeon-Bok Kim, Min-Kyoung Kang, Jong Kyu Lee, and Seung-Chan Park
- Subjects
Transcription, Genetic ,Physiology ,Molecular Sequence Data ,Plant Science ,Abietadiene synthase ,Cyclopentanes ,Biology ,Acetates ,chemistry.chemical_compound ,Rapid amplification of cDNA ends ,Multienzyme Complexes ,Sequence Analysis, Protein ,Transferases ,Complementary DNA ,Gene expression ,Gene family ,Amino Acid Sequence ,Oxylipins ,RNA, Messenger ,Cloning, Molecular ,Gene ,Aldose-Ketose Isomerases ,Phylogeny ,Plant Proteins ,Methyl jasmonate ,Genetic Complementation Test ,Pinus ,Molecular biology ,Wood ,Metabolic pathway ,Erythritol ,chemistry ,Biochemistry ,biology.protein ,Sugar Phosphates ,Oxidoreductases ,Sequence Alignment ,Resins, Plant ,Signal Transduction - Abstract
Pinus densiflora Siebold et Zucc. is the major green canopy species in the mountainous area of Korea. To assess the response of resin acid biosynthetic genes to mechanical and chemical stimuli, we cloned cDNAs of genes encoding enzymes involved in the 2-C-methyl-d-erythritol 4-phosphate (MEP) pathway (1-deoxy-d-xylulose 5-phosphate synthase (PdDXS), 1-deoxy-d-xylulose 5-phosphate reductoisomerase (PdDXR) and 1-hydroxy-2-methyl-2-(E)-butenyl 4-diphosphate reductase (PdHDR)) by the rapid amplification of cDNA ends (RACE) technique. In addition, we cloned the gene encoding abietadiene synthase (PdABS) as a marker for the site of pine resin biosynthesis. PdHDR and PdDXS occurred as two gene families. In the phylogenetic trees, PdDXSs, PdDXR and PdHDRs each formed a separate clade from their respective angiosperm homologs. PdDXS2, PdHDR2 and PdDXR were most actively transcribed in stem wood, whereas PdABS was specifically transcribed. The abundance of PdDXS2 transcripts in wood in the resting state was generally 50-fold higher than the abundance of PdDXS1 transcripts, and PdHDR2 transcripts were more abundant by an order of magnitude in wood than in other tissues, with the ratio of PdHDR2 to PdHDR1 transcripts in wood being about 1. Application of 1 mM methyl jasmonate (MeJA) selectively enhanced the transcript levels of PdDXS2 and PdHDR2 in wood. The ratios of PdDXS2 to PdDXS1 and PdHDR2 to PdHDR1 reached 900 and 20, respectively, on the second day after MeJA treatment, whereas the transcript level of PdABS increased twofold by 3 days after MeJA treatment. Wounding of the stem differentially enhanced the transcript ratios of PdDXS2 to PdDXS1 and PdHDR2 to PdHDR1 to 300 and 70, respectively. The increase in the transcript levels of the MEP pathway genes in response to wounding was accompanied by two orders of magnitude increase in PdABS transcripts. These observations indicated that resin acid biosynthesis activity, represented by PdABS transcription, was correlated with the selective transcriptions of PdDXS2 and PdHDR2. Introduction of PdDXS2, PdHDR1 and PdHDR2 rescued their respective knockout Escherichia coli mutants, confirming that at least these three genes were functionally active. Intracellular targeting of the green fluorescent protein fused to the N-terminal 100 amino acid residues of these genes in the Arabidopsis transient expression system showed that the proteins were all targeted to the chloroplasts. Our results suggest that the MEP pathway regulates resin biosynthesis in the wood of P. densiflora by differential transcription of the multiple PdDXS and PdHDR genes.
- Published
- 2009
34. A Case of Exogenous Lipoid Pneumonia after Ingestion of Squalene in Patients with Achalasia
- Author
-
Dong Myung Huh, Yeon Jae Kim, Byung Ki Lee, Chi Young Jung, Hye Jin Seo, Yu Jin Lee, Jae Kwang Lee, Seung Chan Park, Kyung Rak Sohn, and Jung Chul Park
- Subjects
Pathology ,medicine.medical_specialty ,business.industry ,Achalasia ,Shark liver oil ,Disease ,medicine.disease ,Gastroenterology ,Squalene ,chemistry.chemical_compound ,Pneumonia ,chemistry ,Internal medicine ,medicine ,Ingestion ,In patient ,Exogenous lipoid pneumonia ,business - Abstract
Exogenous lipoid pneumonia (ELP) is a chronic inflammatory reaction of the lungs resulting from the aspiration of vegetable, animal or mineral oils. Squalene, is a derivative of shark liver oil that is taken as a traditional remedy in some Asian countries, and is used widely also in cosmetics. Similar to the symptoms in most cases of oil aspiration, the symptoms of squalene-induced lipoid pneumonia are either absent or nonspecific. Hence, the disease is generally detected incidentally. Although many cases with predisposing factors have been reported, ELP with achalasia is quite rare. We report a 47-year old woman with achalasia who developed ELP after ingesting squalene. The patient was treated successfully by supportive care and surgical treatment of the achalasia.
- Published
- 2008
- Full Text
- View/download PDF
35. Effect of Contact Resistance Between Side-Bar and Secondary Conductors in a Linear Motor With a Cage-Type Secondary.
- Author
-
Seung-Chan Park and Kim, Byung-Taek
- Subjects
INDUCTION motors ,ELECTRICAL conductors ,CONTACT mechanics ,FINITE element method ,MANUFACTURING processes - Abstract
Presents a study that examined the effect of contact resistance between side-bars and secondary conductors in a linear induction motor (LIM). Background on the manufacturing process of the cage-type secondary for LIM; Application of the finite element method to analyze contact resistance; Results and implications.
- Published
- 2003
- Full Text
- View/download PDF
36. Novel Topology of Unequal Air Gap in a Single-Phase Brushless DC Motor.
- Author
-
Byung-Il Kwon, Byoung-Yull Yang, Seung-Chan Park, and Young-Sun Jin
- Subjects
BRUSHLESS electric motors ,TOPOLOGY ,FINITE element method - Abstract
Provides information on a study which presented a topology of the unequal air gaps in a single-phase brushless direct current motor. Overview of the topology of unequal air gap; Formulation of the finite element analysis; Results.
- Published
- 2001
- Full Text
- View/download PDF
37. Influence on Brushless DC Motor Performance Due to Unsymmetric Magnetization Distribution in Permanent Magnet.
- Author
-
Seung-Chan Park and Tae-Ho Yoon
- Subjects
ELECTRIC motors ,MAGNETICS ,FINITE element method - Abstract
Focuses on a study which examined the influence of change in the magnetic parameter on brushless DC motor performances. Details on the finite element analysis; Results; Conclusion.
- Published
- 2000
- Full Text
- View/download PDF
38. Design of single-sided linear induction motor using the finite element method and SUMT.
- Author
-
Dal-Ho Im, Seung-Chan Park, and Jee-Won Im
- Published
- 1993
- Full Text
- View/download PDF
39. Regulation of resin acid synthesis in Pinus densiflora by differential transcription of genes encoding multiple 1-deoxy-D-xylulose 5-phosphate synthase and 1-hydroxy-2-methyl-2-(E)-butenyl 4-diphosphate reductase genes.
- Author
-
Yeon-Bok Kim, Sang-Min Kim, Min-Kyoung Kang, Tomohisa Kuzuyama, Jong Kyu Lee, Seung-Chan Park, Sang-chul Shin, and Soo-Un Kim
- Subjects
WOOD preservatives ,PLANT genetics ,JAPANESE red pine ,GENETIC transcription ,GENETIC code ,BIOSYNTHESIS ,PLANT species - Abstract
Pinus densiflora Siebold et Zucc. is the major green canopy species in the mountainous area of Korea. To assess the response of resin acid biosynthetic genes to mechanical and chemical stimuli, we cloned cDNAs of genes encoding enzymes involved in the 2-C-methyl-<$O_SCPLOW>D<$C_SCPLOW>-erythritol 4-phosphate (MEP) pathway (1-deoxy-<$O_SCPLOW>D<$C_SCPLOW>-xylulose 5-phosphate synthase (PdDXS), 1-deoxy-<$O_SCPLOW>D<$C_SCPLOW><$O_SCPCAP>-<$C_SCPCAP>xylulose 5-phosphate reductoisomerase (PdDXR) and 1-hydroxy-2-methyl-2-(E)-butenyl 4-diphosphate reductase (PdHDR)) by the rapid amplification of cDNA ends (RACE) technique. In addition, we cloned the gene encoding abietadiene synthase (PdABS) as a marker for the site of pine resin biosynthesis. PdHDR and PdDXS occurred as two gene families. In the phylogenetic trees, PdDXSs, PdDXR and PdHDRs each formed a separate clade from their respective angiosperm homologs. PdDXS2, PdHDR2 and PdDXR were most actively transcribed in stem wood, whereas PdABS was specifically transcribed. The abundance of PdDXS2 transcripts in wood in the resting state was generally 50-fold higher than the abundance of PdDXS1 transcripts, and PdHDR2 transcripts were more abundant by an order of magnitude in wood than in other tissues, with the ratio of PdHDR2 to PdHDR1 transcripts in wood being about 1. Application of 1 mM methyl jasmonate (MeJA) selectively enhanced the transcript levels of PdDXS2 and PdHDR2 in wood. The ratios of PdDXS2 to PdDXS1 and PdHDR2 to PdHDR1 reached 900 and 20, respectively, on the second day after MeJA treatment, whereas the transcript level of PdABS increased twofold by 3 days after MeJA treatment. Wounding of the stem differentially enhanced the transcript ratios of PdDXS2 to PdDXS1 and PdHDR2 to PdHDR1 to 300 and 70, respectively. The increase in the transcript levels of the MEP pathway genes in response to wounding was accompanied by two orders of magnitude increase in PdABS transcripts. These observations indicated that resin acid biosynthesis activity, represented by PdABS transcription, was correlated with the selective transcriptions of PdDXS2 and PdHDR2. Introduction of PdDXS2, PdHDR1 and PdHDR2 rescued their respective knockout Escherichia coli mutants, confirming that at least these three genes were functionally active. Intracellular targeting of the green fluorescent protein fused to the N-terminal 100 amino acid residues of these genes in the Arabidopsis transient expression system showed that the proteins were all targeted to the chloroplasts. Our results suggest that the MEP pathway regulates resin biosynthesis in the wood of P. densiflora by differential transcription of the multiple PdDXS and PdHDR genes. [ABSTRACT FROM AUTHOR]
- Published
- 2009
- Full Text
- View/download PDF
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