34 results on '"Young-Sik Kim"'
Search Results
2. Accurate Characterization of T/R Modules with Consideration of Amplitude/Phase Cross Effect in AESA Antenna Unit.
- Author
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Chang-Soo Ahn, Sang-Mi Chon, Seon-Joo Kim, Young-Sik Kim, and Juseop Lee
- Subjects
PHASED array radar ,RADAR transmitters ,AMPLITUDE modulation ,PHASE shifters ,ANTENNA arrays - Abstract
In this paper, an accurate characterization of a fabricated X-band transmit/receive module is described with the process of generating control data to correct amplitude and phase deviations in an active electronically scanned array antenna unit. In the characterization, quantization errors (from both a digitally controlled attenuator and a phase shifter) are considered using not theoretical values (due to discrete sets of amplitude and phase states) but measured values (of which implementation errors are a part). By using the presented procedure for the characterization, each initial control bit of both the attenuator and the phase shifter is closest to the required value for each array element position. In addition, each compensated control bit for the parasitic cross effect between amplitude and phase control is decided using the same procedure. Reduction of the peak sidelobe level of an array antenna is presented as an example to validate the proposed procedure. [ABSTRACT FROM AUTHOR]
- Published
- 2016
- Full Text
- View/download PDF
3. Front-to-back ratio improvement of a short pyramidal horn antenna using metal strips/ rods in LTE/cellular band.
- Author
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Kyoung-Joo Lee, Soon-Soo Oh, Young-Hwan Lee, and Young-Sik Kim
- Subjects
HORN antennas ,RADIATION absorption ,LONG-Term Evolution (Telecommunications) ,BANDWIDTH allocation ,DIPOLE array antennas - Abstract
This study presents a very short pyramidal horn antenna for monitoring the radiation characteristics of mobile base-station (BS) antennas operating in the long-term evolution (LTE)/cellular band. The proposed short pyramidal horn is integrated with metal strips/rods to overcome deficiencies of the shortened horn, especially in its front-to-back (F/B) ratio. The proposed short horn antenna improves the average F/B ratio by at least 8 dB in the frequency range from 690-960 MHz by controlling the edge diffraction. The total length of the antenna, including a waveguide flange, is only approximately 0.6 λ at 800 MHz. The proposed antenna also retains good characteristics such as a monotonically increasing gain, wide bandwidth, and a good purity of polarisation. The proposed antenna can replace the dipole antenna as a reference gain antenna for both indoor and outdoor measurement systems below the L-band. [ABSTRACT FROM AUTHOR]
- Published
- 2016
- Full Text
- View/download PDF
4. Compact dual-band antenna with a lumped capacitor for wireless local area network applications.
- Author
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Min-Jae Lee, Jung-Ho Ahn, and Young-Sik Kim
- Subjects
WIRELESS LANs ,ANTENNAS (Electronics) ,ANTENNA radiation patterns ,MULTIFREQUENCY antennas ,SYNCHRONOUS capacitors - Abstract
This study presents a compact dual-band antenna for wireless local area network (WLAN) applications. The proposed antenna consists of small striplines on both sides of a substrate and a lumped capacitor on the top side to reduce the antenna size. As a folded monopole-type resonance is occurred in 5 GHz band, the proposed antenna yields dual-band characteristics. The resonant mechanism is also analysed using the equivalent circuit model. Electric characteristics of the proposed antenna such as radiation patterns, peak gains, and radiation efficiencies, are presented through the simulation and measurement under various conditions. The antenna size is only 5 x 9 mm². The proposed antenna can cover both WLAN bands of 2.4 and 5 GHz. [ABSTRACT FROM AUTHOR]
- Published
- 2015
- Full Text
- View/download PDF
5. Low Temperature Sintering and Microwave Dielectric Properties of B2O3-added LiAlSiO4 Ceramics.
- Author
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Sang-Hyo Kweon, Mi-Ri Joung, Jin-Seong Kim, Bo-Yun Kim, Sahn Nahm, Jong-Hoo Paik, Young-Sik Kim, and Tae-Hyun Sung
- Subjects
SINTERING ,SINTER (Metallurgy) ,CERAMICS ,ISOSTATIC pressing ,DIELECTRIC measurements ,PARTICLE size determination ,PARTICLE size distribution - Abstract
The sintering temperature of the LiAlSiO
4 (LAS) ceramics, which exhibited the microwave dielectric properties of ϵτ = 4.8, Q x f = 36 000GHz, and τf =8.0 ppm/°C, decreased below 960°C when B2 O3 was added. The B2 O3 -related liquid phase was formed and assisted the densification of the LAS ceramics at low temperatures. The average grain size of the specimen sintered at 950°C increased with the addition of B2 O3 but decreased when B2 O3 exceeded 12.0 mol%, probably due to the presence of a large amount of liquid phase. The LAS ceramics containing 12.0 mol% of B2 O3 sintered at 950°C exhibited the excellent microwave dielectric properties of ϵτ = 5.3, Qxf = 212 000GHz and τf =-7.7 ppm/°C. [ABSTRACT FROM AUTHOR]- Published
- 2011
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- View/download PDF
6. Effect of soil metal contamination on glyphosate mineralization: Role of zinc in the mineralization rates of two copper-spiked mineral soils.
- Author
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Bojeong Kim, Young Sik Kim, Bo Min Kim, Hay, Anthony G., and McBride, Murray B.
- Subjects
- *
SOIL pollution research , *GLYPHOSATE , *ZINC , *COPPER , *CARBON monoxide - Abstract
A systematic investigation into lowered degradation rates of glyphosate in metal-contaminated soils was performed by measuring mineralization of [C]glyphosate to CO in two mineral soils that had been spiked with Cu and/or Zn at various loadings. Cumulative CO release was estimated to be approximately 6% or less of the amount of [C]glyphosate originally added in both soils over an 80-d incubation. For all but the highest Cu treatments (400 mg kg) in the coarse-textured Arkport soil, mineralization began without a lag phase and declined over time. No inhibition of mineralization was observed for Zn up to 400 mg kg in either soil, suggesting differential sensitivity of glyphosate mineralization to the types of metal and soil. Interestingly, Zn appeared to alleviate high-Cu inhibition of mineralization in the Arkport soil. The protective role of Zn against Cu toxicity was also observed in the pure culture study with Pseudomonas aeruginosa, suggesting that increased mineralization rates in high Cu soil with Zn additions might have been due to alleviation of cellular toxicity by Zn rather than a mineralization specific mechanism. Extensive use of glyphosate combined with its reduced degradation in Cu-contaminated, coarse-textured soils may increase glyphosate persistence in soil and consequently facilitate Cu and glyphosate mobilization in the soil environment. Environ. Toxicol. Chem. 2011; 30:596-601. © 2011 SETAC [ABSTRACT FROM AUTHOR]
- Published
- 2011
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7. Multiband Meandered Monopole Antenna for Mobile Applications.
- Author
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Jae-Kwan Lee, Seongmin Pyo, and Young-Sik Kim
- Subjects
MONOPOLE antennas ,DIGITAL video ,BROADCASTING industry ,GLOBAL Positioning System ,WIRELESS LANs ,MICROSTRIP antennas - Abstract
A multiband meandered monopole antenna is proposed for digital video broadcasting handheld (DVB-H), global positioning system, personal communications service, wireless broadband (Wibro), and wireless local area network (WLAN) applications. The proposed antenna consists of a meandered line, a shorted length strip line, and a conductor strip between a meandered line and a microstrip feed line. By tuning a short strip and a conductor, a multiband impedance matching is achieved. The proposed antenna has an omnidirectional radiation and yields an antenna gain of greater than -3 dBi in the DVB-H band and 4.5 dBi in the Wibro and WLAN bands. Details of the proposed antenna design and experimental results are presented. [ABSTRACT FROM AUTHOR]
- Published
- 2010
- Full Text
- View/download PDF
8. Reconfigurable Circularly Polarized Microstrip Antenna on a Slotted Ground.
- Author
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Won-Sang Yoon, Sang-Min Han, Seongmin Pyo, Jaehoon Lee, In-Chul Shin, and Young-Sik Kim
- Subjects
MICROSTRIP antennas ,POLARIZATION (Nuclear physics) ,PIN diodes ,BANDWIDTHS ,BROADBAND communication systems ,DATA transmission systems - Abstract
A compact square patch antenna with reconfigurable circular polarization (CP) at 2.4 GHz is proposed. Circular polarization is generated by an arc-shaped slot on the ground plane. In order to switch the CP orientation, the current flow direction of the patch is reconfigured via the PIN diodes mounted on the slot. As the slot and bias circuit are not placed on the patch side, the proposed antenna radiates a CP wave without alteration in the main beam direction. From the experimental results, the impedance and CP bandwidths of the proposed antenna have been demonstrated for up to 80 MHz and 25 MHz, respectively. [ABSTRACT FROM AUTHOR]
- Published
- 2010
- Full Text
- View/download PDF
9. Linear Corrector Overcoming Minimum Distance Limitation for Secure TRNG from (17, 9, 5) Quadratic Residue Code.
- Author
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Young-Sik Kim, Ji-Woong Jang, and Dae-Woon Lim
- Subjects
ELECTRONIC wallets ,DATA encryption ,SECURITY management ,INDUSTRIAL management ,DATA protection ,MULTIMEDIA systems ,BROADBAND communication systems ,DATA transmission systems ,TELECOMMUNICATION systems - Abstract
A true random number generator (TRNG) is widely used to generate secure random numbers for encryption, digital signatures, authentication, and so on in cryptosystems. Since TRNG is vulnerable to environmental changes, a deterministic function is normally used to reduce bias and improve the statistical properties of the TRNG output. In this paper, we propose a linear corrector for secure TRNG. The performance of a linear corrector is bounded by the minimum distance of the corresponding linear error correcting code. However, we show that it is possible to construct a linear corrector overcoming the minimum distance limitation. The proposed linear corrector shows better performance in terms of removing bias in that it can enlarge the acceptable bias range of the raw TRNG output. Moreover, it is possible to efficiently implement this linear corrector using only XOR gates, which must have a suitable hardware size for embedded security systems. [ABSTRACT FROM AUTHOR]
- Published
- 2010
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10. Glomeruloid peritoneal implants in ovarian serous borderline tumours – distinction between invasive and non-invasive implants and pathogenesis.
- Author
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Eung-Seok Lee, Anthony S.-Y. Leong, Kim, Insun S., Young-Sik Kim, Ju-Han Lee, and Hyun-Yee Cho
- Subjects
TUMORS ,CARCINOGENESIS ,ARTIFICIAL implants ,PAPILLARY carcinoma ,CANCER invasiveness - Abstract
Aims: To determine whether or not the glomeruloid implants (GI) composed of papillary cores within clear spaces lined by mesothelial cells or tumour cells located in superficial or deep peritoneal tissue in ovarian serous borderline tumours (SBTs) are invasive. Methods and results: We examined the differences in incidence, histological and immunohistochemical findings among three groups: 100 GI with mesothelial cells lining clear space (type I), 100 GI with tumour cells lining clear space (type II), and 100 invasive implants with clefts but no lining cells from 30 cases of SBT with peritoneal implants. The type I lesion had characteristics of non-invasive implants with a tendency for smooth contours (100/100), superficial location (71/100), absence of desmoplasia (100/100) and absence of surrounding destructive invasion (100/100), In contrast, type II GI had irregular contours (67/100), deep location (93/100), presence of desmoplastic reaction (100/100) and presence of destructive invasion (12/100). Immunohistological studies suggested intermediate forms between the two types of lesions. Conclusions: Type I GI are non-invasive implants, whereas type II GI are invasive implants and it is important to evaluate the presence and nature of cells lining the clear space in determining whether implants associated with ovarian SBTs are invasive or not. [ABSTRACT FROM AUTHOR]
- Published
- 2009
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- View/download PDF
11. Wealth Distribution, Inflation Tax, and Societal Benefits of Illiquid Bonds.
- Author
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YOUNG SIK KIM and MANJONG LEE
- Subjects
CURRENCY question ,INTERNATIONAL relations ,BONDS (Finance) ,WEALTH ,FINANCE ,LIQUIDITY (Economics) ,ECONOMICS - Abstract
Illiquid nominal government bonds are shown to have two opposing effects on welfare. First, the relatively poor choose to top-up money balances for future consumption by purchasing nominal bonds at a discount. The wealth distribution becomes more centered with a smaller consumption deviation from the first best. Second, the higher inflation tax on monetary wealth to finance interest payments makes money less valuable, so that the quantity of output produced in exchange for money decreases. The trade-off between the welfare-enhancing effect on wealth distribution and the distortionary effect on output implies the socially optimal discount rate and liquidity. [ABSTRACT FROM AUTHOR]
- Published
- 2009
- Full Text
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12. Characterization of interdigital stub with defected ground structure.
- Author
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Seongmin Pyo, Jung-Woo Baik, Dong-Hyo Lee, and Young-Sik Kim
- Subjects
INTERDIGITAL transducers ,ELECTRIC resonators ,CAPACITANCE meters ,INTEGRATED circuits ,FREQUENCY response - Abstract
A new scheme with an interdigital line and a defected ground structure for dual-band operation is dealt with in this letter. The proposed structure is analyzed using a series L-C resonator model added a parasitic shunt capacitance. The nonlinear phase of this structure is dependent on the dumbbell size of the defected ground. This proposed scheme is applicable for a short-ended stub circuit and a dual pass-band filter at the centre frequencies of 860 and 1810 MHz. © 2009 Wiley Periodicals, Inc. Microwave Opt Technol Lett 51: 1353–1356, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24331 [ABSTRACT FROM AUTHOR]
- Published
- 2009
- Full Text
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13. Clinicopathological and molecular characteristics of Epstein–Barr virus-associated gastric carcinoma: A meta-analysis.
- Author
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Ju-Han Lee, Seo-Hee Kim, Sun-Hee Han, Jung-Suk An, Eung-Seok Lee, and Young-Sik Kim
- Subjects
STOMACH cancer ,META-analysis ,PSYCHOMETRICS ,GASTROINTESTINAL system ,LYMPH nodes - Abstract
There is conflicting data regarding the clinicopathological significance of the risk factors associated with Epstein–Barr virus (EBV)-associated gastric carcinoma (EBVaGC). To address this controversy, we performed a meta-analysis for the clinicopathological and molecular characteristics of EBVaGC. The relevant published studies were reviewed according to the defined selection criteria. The effect sizes of the outcome parameters were estimated by an odds ratio or a weighted mean difference. This meta-analysis included 48 studies that encompassed a total of 9738 patients. The frequency of EBVaGC was 8.8%, and EBVaGC was significantly associated with ethnicity. It was more predominant in men and in younger individuals. Interestingly, EBVaGC was more prevalent in Caucasian and Hispanic patients than in Asian ones. EBVaGC developed most often in the cardia and body, and it generally showed the diffuse histological type. EBV was highly prevalent in the patients with lymphoepithelial carcinoma. EBVaGC was closely associated with remnant cancer and a CpG island methylator-high status, but not with Helicobacter pylori infection, a TP53 expression, and p53 mutation. In addition, EBVaGC was not significantly associated with the depth of invasion, lymph node metastasis, or the clinical stage. The clinicopathological and molecular characteristics of EBVaGC are quite different from those of conventional gastric adenocarcinoma. However, further study is needed to determine the effect of EBV on the survival of EBVaGC patients. [ABSTRACT FROM AUTHOR]
- Published
- 2009
- Full Text
- View/download PDF
14. Synthesis and Microwave Dielectric Properties of MgSiO3 Ceramics.
- Author
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Myung-Eun Song, Jin-Seong Kim, Mi-Ri Joung, Sahn Nahm, Young-Sik Kim, Jong-Hoo Paik, and Byung-Hyun Choi
- Subjects
CERAMICS ,DIELECTRICS ,MILLIMETER wave communication systems ,MILLIMETER wave devices ,ISOSTATIC pressing ,SINTERING ,POWDER metallurgy - Abstract
MgSiO
3 ceramics were synthesized and their microwave dielectric properties were investigated. The Mg2 SiO4 phase was formed at temperatures lower than 1200°C, while the orthorhombic MgSiO3 phase started to form by the reaction of SiO2 and Mg2 SiO4 in the specimen fired at 1200°C. The structure of the MgSiO3 ceramics was transformed from orthorhombic to monoclinic when the sintering temperature exceeded 1400°C. A dense microstructure was developed for the specimens sintered at above 1350°C. The excellent microwave dielectric properties of ℇr =6.7, Q× f=121 200 GHz, and τf =−17 ppm/°C were obtained from the MgSiO3 ceramics sintered at 1380°C for 13 h. [ABSTRACT FROM AUTHOR]- Published
- 2008
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15. Clinicopathologic Significance of BRAF V600E Mutation in Papillary Carcinomas of the Thyroid.
- Author
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Ju-Han Lee, Eung-Seok Lee, and Young-Sik Kim
- Subjects
GENES ,GENETIC mutation ,THYROID cancer ,META-analysis ,GENETIC markers - Abstract
The article focuses on a study about the clinicopathologic significance of BRAF V600E mutation in papillary thyroid carcinoma (PTC). A meta-analysis was executed to determine the usefulness of BRAF mutation as a prognostic marker of PTC. Results indicate that BRAF mutation is connected with histologic subtype, the presence of extrathyroidal extension and higher clinical stage. It adds that no relationship exists between BRAF mutation and age, sex, race or tumor size.
- Published
- 2007
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16. Expression of class II β-tubulin in non-melanoma cutaneous tumors.
- Author
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Joo-Young Roh, Sun-Ho Kee, Jung-Woo Choi, Ji-Hye Lee, Ju-Han Lee, Eung Seok Lee, and Young-Sik Kim
- Subjects
TUBULINS ,MELANOMA ,TUMORS ,KERATINOCYTES ,MICROTUBULES ,SKIN - Abstract
Background: Different combinations of β-tubulin isotypes contribute to the diverse functions of microtubules (MTs). Class II β-tubulin (class II tubulin) is up-regulated in differentiated keratinocytes. In contrast, the expression of class II tubulin in follicular differentiation and cutaneous tumors has not been studied. Methods: The immunohistochemical expression of class II tubulin was investigated in 117 cutaneous tumors: 30 squamous cell carcinomas (SCCs), seven keratoacanthomas (KAs), 57 basal cell carcinomas (BCCs), 23 trichoepitheliomas (TEs), and in the adjacent non-neoplastic skin. Results: Class II tubulin was expressed in the keratinocytes of the granular layer, melanocytes, hair cortical and cuticular cells, inner root sheath (IRS), companion layer (CL) of the outer root sheath (ORS), and mesenchymal cells with Schwannian or myogenic differentiation. Moreover, class II tubulin expression was increased in the areas of squamous or follicular differentiation in cutaneous tumors. On grading the follicular differentiation or myofibroblastic response with anti-class II tubulin, TE showed follicular differentiation more frequently (p < 0.001) with less of a myofibroblastic response (p = 0.001) than BCC. Conclusions: Class II tubulin expression is closely related to squamous or follicular differentiation and may be helpful in distinguishing most SCCs from KAs and BCC from TE. However, it does not reliably distinguish well-differentiated, crateriform SCC from KA. [ABSTRACT FROM AUTHOR]
- Published
- 2007
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17. Phenology of the rhodomelarian algae Neorhodomela aculeata and Ceramium kondoi and their survival strategies against herbivorous snails.
- Author
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Han Gil Choi, Ji Hee Lee, Young-Kug Choo, Kyu-Yun Chai, Young Sik Kim, Jung-Soo Han, Anchana Prathep, and Ki Wan Nam
- Subjects
PHENOLOGY ,ALGAE ,ANTS ,SNAILS ,FOOD preferences ,PREDATION ,PREDATORY animals - Abstract
The seasonal growth and reproductive phenology of Neorhodomela aculeata (Perestenko) Masuda and Ceramium kondoi Yendo, and the food preferences of herbivorous snails were examined to elucidate (i) why snails select the fronds of N. aculeata for their habitat; and (ii) the survival strategies of the two red algae under grazing pressures. The maximal lengths and weights of both algal species were recorded for each season over a 12-month period beginning with the spring of 2003. C. kondoi grew in length at a faster rate than N. aculeate, whereas the turf alga N. aculeata produced new branches from the tips of broken branches. The reproductive period of C. kondoi was between the spring and summer but the reproductive organs of N. aculeata were observed throughout the year. The algal loss rate of fresh N. aculeata to snails was low but snails had a food preference for N. aculeata when compared to C. kondoi in an artificial food experiment. These results indicate that snails may adapt to chemical compounds characteristic of N. aculeata and that the alga further reduces predation damage by its structural resistance. In conclusion, the survival strategies of C. kondoi appear to be rapid growth, seasonal sexual reproduction, and a delicately branched frond morphology that reduces stable feeding patterns of its predators plus high tissue nitrogen content, whereas the survival strategy of N. aculeata includes regenerative growth responses, structural toughness and chemical defenses while under the grazing pressure of herbivorous snails. [ABSTRACT FROM AUTHOR]
- Published
- 2006
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18. Proteomic analysis of pulmonary sclerosing hemangioma.
- Author
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Lian-Jin Jin, Bong Kyung Shin, Woon Yong Jung, Hyun-Juu Lee, Su Jin Cho, Joung-Ho Han, Seong-Yeon Ha, Ae-Ree Kim, Young Sik Kim, In Sun Kim, Chang-Sub Uhm, and Han Kyeom Kim
- Published
- 2006
- Full Text
- View/download PDF
19. Epstein-Barr virus infection in sarcomatoid renal cell carcinoma tissues.
- Author
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Kwang Hee Kim, Eun Mee Han, Eung Seok Lee, Hong Seok Park, Insun Kim, and Young-Sik Kim
- Subjects
EPSTEIN-Barr virus diseases ,HERPESVIRUS diseases ,VIRUS diseases ,LYMPHOCYTES ,RENAL cell carcinoma ,RENAL cancer - Abstract
To determine whether Epstein-Barr virus (EBV) infection is related to renal cell carcinoma (RCC) tissues. We investigated EBV infection and its genotypes in 73 cases of different types of RCC and 18 of non-neoplastic kidney. EBV infection and its genotypes were determined by EBV-encoded RNAs in situ hybridization (EBER-ISH) and polymerase chain reactions for EBV-encoded nuclear antigen 1 (EBNA-1) and EBNA-3C. The immunophenotype and EBV status of the EBV-infected cells were examined by double-labelling of EBER-ISH and/or immunohistochemistry for lymphoid cell markers, EBV proteins, and CD21. EBER-ISH signals were detected in five of 73 RCC tissues (6.8%), but in none of 18 non-neoplastic kidneys. Interestingly, EBER-ISH was positive only in five of the 10 sarcomatoid RCCs, and of these, four also showed amplification of EBNA-1. EBV was located exclusively in the tumour-infiltrating B lymphocytes of sarcomatoid RCCs. The genotype of EBV was determined as type 1. A few EBV-infected B cells expressed BZLF1 (an EBV immediate-early gene product) while none expressed EBNA-2 or latent membrane protein 1. This indicates that the B cells are of EBV latency type I, often replicating EBV. EBV infection did not affect the survival rates of patients with sarcomatoid RCC ( P = 0.635, Kaplan–Meier analysis, log-rank test). EBV is present only in tumour-infiltrating B lymphocytes of sarcomatoid RCCs. The present study suggests that sarcomatoid RCC modulates a function of EBV-specific T cells controlling EBV replication, or stimulates differentiation of memory B cells into plasma cells. [ABSTRACT FROM AUTHOR]
- Published
- 2005
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20. Broadband millimeter-wave planar antenna array with a waveguide and microstrip-feed network.
- Author
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Soon-Soo Oh, John Heo, Dong-Hyeon Kim, Jae-Wook Lee, Myung-Sun Song, and Young-Sik Kim
- Subjects
MICROWAVE antennas ,ANTENNAS (Electronics) ,MICROWAVE devices ,STRIP transmission lines ,ANTENNA feeds - Abstract
In this paper, we describe a fixed-beam broadband planar antenna array at millimeter-wave frequencies. The antenna is fed by waveguide-feed and microstrip-feed networks. In order to ensure fixed beams and a broad bandwidth, a subarray concept is introduced. For efficient coupling, a novel waveguide-to-slot transition consisting of a slot pair and a narrow conductive bar is proposed. Simulated and measured bandwidth is found to be more than 7.1% from 40.5–43.5 GHz. The main beam directions are broadside over all frequencies. The maximum measured antenna gain is 30.2 dBi at 42.0 GHz. © 2004 Wiley Periodicals, Inc. Microwave Opt Technol Lett 42: 283–287, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.20279 [ABSTRACT FROM AUTHOR]
- Published
- 2004
- Full Text
- View/download PDF
21. Strong coupled microstrip tapered feedlines for the applications to filters and antennas.
- Author
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Sang-Min Han and Young-Sik Kim
- Subjects
- *
COUPLED mode theory (Wave-motion) , *THEORY of wave motion , *STRIP transmission lines , *MULTICONDUCTOR transmission lines , *ELECTRIC impedance - Abstract
In this paper, new feeding structures with strong coupling using linearly and exponentially tapered lines are proposed in order to overcome the design problems due to coupling losses and impedance mismatching. The tapered feedlines are characterized for the optimum feedline length of λg/2 and insertion losses (ILs) and fractional bandwidths (FBWs) with respect to the feeding angle. The proposed structures have been applied to BPFs and patch antennas. The experimental results show lower insertion losses and better matching properties, compared with circuits with conventional feedlines. © 2003 Wiley Periodicals, Inc. Microwave Opt Technol Lett 39: 505–508, 2003 [ABSTRACT FROM AUTHOR]
- Published
- 2003
- Full Text
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22. Analysis of a new bandpass filter with two ring DRs using the FDTD method.
- Author
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Ho-Tark Hwang, Sang-Ho Lim, Soon-Soo Oh, Jichai Jeong, and Young-Sik Kim
- Subjects
BANDPASS filters ,ELECTRIC filters ,ELECTRIC circuits ,STRIP transmission lines ,MULTICONDUCTOR transmission lines - Abstract
In this paper, a new bandpass filter inserting a microstrip-line resonator between two ring dielectric resonators is described in an MIC environment. This filter is designed using the general filter design technique, and is analyzed using the FDTD method. The designed result shows good agreement with the experimental and simulated ones. © 2001 John Wiley & Sons, Inc. Microwave Opt Technol Lett 29: 319–322, 2001. [ABSTRACT FROM AUTHOR]
- Published
- 2001
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23. A CHANGE OF SCALE FORMULA FOR WIENER INTEGRALS OF CYLINDER FUNCTIONS ON THE ABSTRACT WIENER SPACE II.
- Author
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YOUNG SIK KIM
- Published
- 2001
24. Chondromyxoid fibroma of the distal phalanx of the great toe: A tumor with unusual histological findings.
- Author
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Young-Sik Kim, Seung Ju Jeon, Sang Hoon Cha, and Insun Kim
- Subjects
- *
FIBROMAS , *SPECTRUM analysis - Abstract
Examines the chondromyxoid fibroma of the distal phalanx on the great toe. Visualization on the spectrum of histology; Separation of hypercellular chondromyxoid by hypocellular fibrous tissue; Aggregation of tumor cells with pleomorphic multinucleate within chondromyxoid matrix.
- Published
- 1998
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25. A CHANGE OF SCALE FORMULA FOR WIENER INTEGRALS OF CYLINDER FUNCTIONS ON ABSTRACT WIENER SPACE.
- Author
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YOUNG SIK KIM
- Published
- 1998
26. A compact low-pass filter with double-step impedance shunt stub and defected ground structure for wideband rejection.
- Author
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Jae-Kwan Lee, Dong-Hyo Lee, and Young-Sik Kim
- Subjects
MICROWAVE filters ,BANDWIDTHS ,BROADBAND communication systems ,ELECTRIC impedance ,SHUNT electric reactors - Abstract
In this letter, a compact low-pass filter (LPF) with wideband rejection using double-step impedance shunt stub (SISS) and barbell-type defected ground structure (DGS) is presented. This proposed LPF has similar characteristics in bandwidth, but good wideband rejection and cutoff sharpness compared with the same size conventional LPF, using SISS and conventional DGS. The size reduction of the proposed LPF is about 23% more than the conventional one. Good agreements are achieved between the simulated and measured results. © 2009 Wiley Periodicals, Inc. Microwave Opt Technol Lett 52: 132–134, 2010; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24883 [ABSTRACT FROM AUTHOR]
- Published
- 2010
- Full Text
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27. A new coplanar waveguide bandpass filter using interdigital DGS.
- Author
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Jae-Kwan Lee and Young-Sik Kim
- Subjects
- *
BANDPASS filters , *WAVEGUIDES , *SIMULATION methods & models , *CAPACITORS , *BANDWIDTHS - Abstract
In this letter, a new bandpass filter (BPF) with coplanar waveguide using interdigital capacitor and interdigital defected ground structure is proposed. The proposed BPF size is reduced about 33% compared to the BPF using a conventional DGS one. Both filters have lower and higher cutoff frequency at about 1.4 and 2.4 GHz. The measured results are well agreed with the simulation ones. © 2009 Wiley Periodicals, Inc. Microwave Opt Technol Lett 51: 2915–2917, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24804 [ABSTRACT FROM AUTHOR]
- Published
- 2009
- Full Text
- View/download PDF
28. Switchable Printed Yagi-Uda Antenna with Pattern Reconfiguration.
- Author
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Jung-Woo Baik, Seongmin Pyo, Tae-Hak Lee, and Young-Sik Kim
- Subjects
PRINTED circuits ,ELECTRIC circuits ,RADIO frequency ,DIGITAL communications ,DATA transmission systems ,RADIO measurements ,BROADBAND communication systems ,RADIO waves ,RADIO wave propagation - Abstract
A switchable Yagi-Uda antenna prototype with radiation pattern reconfiguration is presented in this letter. The proposed reconfigurable antenna is based on the concept of switching between the reflector and director of a Yagi-Uda antenna using a radio frequency PIN diode. As a result, the minimum/maximum radiation can be steered towards desired signals or away from interfering signals in opposite directions. The measured 10 dB impedance bandwidth and gain are 210 MHz (7%) and 8.02 dBi at 3 GHz, respectively. Details of the antenna design and its performance are described and empirically analyzed. [ABSTRACT FROM AUTHOR]
- Published
- 2009
- Full Text
- View/download PDF
29. CPW-fed compact meander and L-shape monopole antenna for dual-band WLAN applications.
- Author
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Chung-Kyun Ham, Jung-Woo Baik, and Young-Sik Kim
- Subjects
MONOPOLE antennas ,ANTENNAS (Electronics) ,WAVEGUIDES ,WIRELESS LANs ,ELECTRICAL conductors - Abstract
A compact coplanar waveguide (CPW)-fed monopole antenna is proposed for dual-band wireless local area network (WLAN) applications. The proposed antenna, which consists of a meander strip and a L-shaped strip, has compact size of 20 mm × 17 mm × 1.6 mm including the ground. The impedance bandwidth with 10 dB return loss is about 330 MHz (2.3–2.63 GHz) for 2.4 GHz band and 950 MHz (4.93–5.88 GHz) for 5 GHz band. The measured peak gains are 1.7 dBi at lower and 2.8 dBi at higher band, respectively. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 3147–3149, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23914 [ABSTRACT FROM AUTHOR]
- Published
- 2008
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- View/download PDF
30. A CPW-fed staircase monopole UWB antenna with band-notched frequency in the WLAN band.
- Author
-
Sang Joong Kim, Hyoung Sik Lee, and Young-Sik Kim
- Subjects
WAVEGUIDES ,ULTRA-wideband antennas ,ELECTRIC impedance ,MONOPOLE antennas ,ELECTRIC waves - Abstract
A coplanar waveguide (CPW)-fed ultra-wideband staircase monopole antenna with a frequency-notch characteristic is presented. The proposed antenna consists of a planar four-step staircase rectangular monopole with a ground short-circuited stub, open stubs at the ground part, and two-step impedance transformer at the CPW-fed line. The impedance bandwidth is increased due to an offset feeding technique and one-side ground notch. The notched frequency band can be accomplished by means of the method that involves adding open stubs at the ground. The measured results are in good agreement with the simulated ones. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 2545–2547, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22775 [ABSTRACT FROM AUTHOR]
- Published
- 2007
- Full Text
- View/download PDF
31. A dual-passband microstrip open-loop resonator filter.
- Author
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Chang-Soo Ahn, Juseop Lee, and Young-Sik Kim
- Subjects
RESONATORS ,MICROSTRIP antennas ,MICROWAVE antennas ,STRIP transmission lines ,ELECTRIC filters - Abstract
In this paper, a design technique that includes a synthesis procedure and a realization method for a microstrip open-loop resonator filter with two passbands is described. Transmission zeros of the filter-transfer function are employed to split a single passband into two passbands, and the filter-coupling structure used to realize two passbands is also given. The measured result shows good agreement with the synthesized one. © 2005 Wiley Periodicals, Inc. Microwave Opt Technol Lett 46: 241–243, 2005; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.20956 [ABSTRACT FROM AUTHOR]
- Published
- 2005
- Full Text
- View/download PDF
32. Role of aldosterone in diabetic nephropathy.
- Author
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DAE RYONG CHA, YOUNG SUN KANG, SANG YOUB HAN, YI HWA JEE, KUM HYUN HAN, HYOUNG KYU KIM, JEE YOUNG HAN, and YOUNG SIK KIM
- Subjects
ALDOSTERONE ,CYTOKINES ,COLLAGEN ,EPITHELIAL cells ,DIABETIC nephropathies - Abstract
In the last 10 years, many studies have focused on the non-classical action of aldosterone. One of the most important new aspects of aldosterone is its pathogenic role as proinflammatory and profibrotic molecules. It has been reported that aldosterone induces myocardial fibrosis and vascular inflammation through up-regulation of various proinflammatory and profibrotic cytokines. We investigated the effect of aldosterone and spironolactone, which is a non-selective mineralocorticoid receptor antagonist, on monocyte chemoattractant peptide (MCP-1) and collagen synthesis in cultured mesangial and tubular epithelial cells. In addition, to evaluate the effect of spironolactone on diabetic nephropathy, we used Otsuka Long-Evans Tokushima Fatty (OLETF) rats which are known type 2 diabetic animal models. Spironolactone treatment did not induce any significant change in blood glucose levels and blood pressure. However, spironolactone therapy significantly inhibited urinary albumin and MCP-1 excretion. Spironolactone treatment also suppressed renal mRNA expression for MCP-1, macrophage migration inhibitory factor (MIF) as well as intrarenal protein synthesis for ED-1 and MIF. Morphologically, spironolactone treatment significantly prevented glomerulosclerosis, collagen deposition and connective tissue growth factor (CTGF) expression in diabetic rats. In cultured cell experiments, aldosterone directly increased the MCP-1, collagen secretion and spironolactone treatment abolished aldosterone-induced MCP-1 and collagen synthesis. Surprisingly, aldosterone treatment did not induce any significant change in TGFβ1 gene transcription. Finally, we found that NF-kB activity was increased after stimulation with aldosterone and spironolactone therapy inhibited their activation. In addition, prior treatment with pyrrolidine dithiocarbamate (PDTC), which is a NF-KB inhibitor, inhibited aldosterone-induced MCP-1 protein secretion. These results suggest that aldosterone blockade could play a role in preventing the progression of diabetic nephropathy via anti-inflammatory and antifibrotic mechanisms. [ABSTRACT FROM AUTHOR]
- Published
- 2005
- Full Text
- View/download PDF
33. Compact hairpin-shaped duplexer using a BMT substrate with high dielectric constant.
- Author
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Koo Hyung Kwon, Sang-Min Han, Shan Nahm, Min Han Kim, and Young-Sik Kim
- Subjects
MICROWAVE devices ,MICROWAVES ,ELECTRONIC equipment ,DIELECTRICS ,ELECTRIC circuits ,BARIUM compounds - Abstract
In this paper, a compact planar microwave duplexer on a high-dielectric substrate is proposed. As Ba(Mg
1/3 Ta2/3 )O3 (BMT) has good dielectric performances with a high-dielectric constant of ℇr = 23, it is suitable for application on printed circuit boards for compact-size circuits. The BMT substrate is fabricated using a tape-casting process; then, metal patterns are screen-printed upon it and silver pasted. An open-loop ring-type duplexer is designed and implemented on the BMT substrate. A size reduction of about 80% is achieved without any degrading duplexer performances, compared with the same one fabricated on a commercial substrate (ℇr = 6.15). © 2004 Wiley Periodicals, Inc. Microwave Opt Technol Lett 41: 251–253, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.20108 [ABSTRACT FROM AUTHOR]- Published
- 2004
- Full Text
- View/download PDF
34. New compact broadband phase shifters using coupled lines.
- Author
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Sang-Min Han, Koo Hyung Kwon, and Young-Sik Kim
- Subjects
BROADBAND communication systems ,PHASE shifters ,ELECTRONIC equipment ,DIRECTIONAL couplers ,WAVEGUIDES ,ANTENNA arrays - Abstract
This paper presents two types of phase shifters using parallel coupled lines as compact and broadband couplers. Phase shifts are enabled by varying the varactor capacitances or by switching the PIN diode ON/OFF. Both have shown about 40% bandwidth within ±3.5° phase error. While an adjustable phase control over 65° is obtained by the phase shifter with varactor diodes, 180° is yielded by that with PIN diodes. © 2003 Wiley Periodicals, Inc. Microwave Opt Technol Lett 36: 399–400, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.10775 [ABSTRACT FROM AUTHOR]
- Published
- 2003
- Full Text
- View/download PDF
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