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In developing terahertz (THz) technologies that are more suitable for industrial applications, we have focused on research on continuous-wave (CW) THz technologies to develop small, low-cost, and multifunctional THz devices and systems. In the course of this research, we have developed several key devices such as widely tunable compact beating sources in the form of dual-mode lasers, THz emitters, including nano-electrode-photomixers and unitraveling carrier photodiode photomixers, and highly sensitive THz detectors, such as Schottky barrier diodes. In this paper, along with our recently obtained results that demonstrate the enhanced performance of these devices, we also present an example of a practical industrial application of our CW THz system: a nondestructive evaluation (NDE) system. The system described can be applied in the car manufacturing factory as an NDE technique to find process errors. Although further improvements to photonics-based THz technologies are necessary, we believe that efforts in this field will begin an era of THz technologies as a widely used industrial technique.

The purposes of the study were to determine whether there are differences in texture analysis parameters between tonsil cancers and normal tonsils, and to correlate texture analysis with 18F-FDG PET/CT to investigate the relationship between texture analysis and metabolic parameters. Sixty-four patients with squamous cell carcinoma of the palatine tonsil were included. A ROI was drawn, including all slices, to involve the entire tumor. The contralateral normal tonsil was used for comparison with the tumors. Texture analysis parameters, mean, standard deviation (SD), entropy, mean positive pixels, skewness, and kurtosis were obtained using commercially available software. Parameters were compared between the tumor and the normal palatine tonsils. Comparisons were also performed among early tonsil cancer, advanced tonsil cancer, and normal tonsils. An ROC curve analysis was performed to assess discrimination of tumor from normal tonsils. Correlation between texture analysis and 18F-FDG PET/CT was performed. Compared to normal tonsils, the tumors showed a significantly lower mean, higher SD, higher entropy, lower skewness, and higher kurtosis on most filters (p

The capacity of the propulsion engine is reduced due to the Energy Efficiency Design Index (EEDI) regulations, so more precise prediction of the propulsion performance is required. The heave and pitch motions of ships are main influences on propeller performance in waves. Therefore, this study investigated the effect of a propeller's immersion depth and tilt angle on the propeller performance in calm water and in waves. Numerical simulations of propeller open water test were performed with several immersion depths, tilt angles, heave motion, and pitch motion. Model tests were also carried out at several immersion depths and tilt angles. A prediction method was then developed to predict the performance of a propeller with motion in waves. Variation of the propeller performance due to the immersion depth and tilt angle in calm water was applied as a function of the advance ratio (J) and immersion depth (h/D), including the effects of waves and motion. The performance of a propeller with heave motion in waves was predicted using the completed estimation equation. Even though the fluctuation width could not be predicted, the trends were very similar. The results of this study could be considered useful for predicting a ship's performance in waves.

The purpose of this study was to investigate the differences in motor cortex susceptibility among patients with amyotrophic lateral sclerosis (ALS), cerebrovascular disease (CVD), and healthy controls using quantitative susceptibility mapping (QSM). We retrospectively reviewed 78 QSM images from 26 patients with ALS, 26 age- and sex-matched patients with CVD, and 26 healthy controls. A region of interest was drawn in the hand lobule of both the motor cortexes and subcortical white matter. The relative susceptibility (RS) of the motor cortex was obtained by subtracting the susceptibility of the subcortical white matter from that of the motor cortex. We compared the cortexmean, cortexmax, subcortical white mattermean, RSmean, and RSmax values among the three groups using analysis of variance and Tukey’s post hoc test. Receiver operating characteristic (ROC) curve analysis was also performed. There were significant differences in the cortexmean, cortexmax, RSmean, and RSmax among the three groups, with higher values in patients with ALS (p = 0.01, p = 0.004, p

A 31-year-old female with systemic lupus erythematosus (SLE) presented with fever, headache, seizures and mental status changes. Brain MRI showed T2 hyperintense lesions in the cerebellum and frontal white matter and a lesion in the cerebellum exhibited hemorrhagic changes and peripheral ring enhancement. The MRI features of listerial encephalitis are difficult to differentiate from those of neuropsychiatric SLE and various other diseases. Here, we report a case of hemorrhagic listerial encephalitis in a patient with SLE.

In developing terahertz (THz) technologies that are more suitable for industrial applications, we have focused on research on continuous-wave (CW) THz technologies to develop small, low-cost, and multifunctional THz devices and systems. In this study, we present an example of a practical industrial application of our CW THz system, a nondestructive evaluation (NDE) system: cost-effective high-speed 1-D/2-D reflective imaging system and real-time thickness monitoring system of slurry film. Although further improvements to photonics-based THz technologies are necessary, we believe that efforts in this field will begin an era of THz technologies as a widely-used industrial technique.

Terahertz continuous wave (CW) system for measuring sub-100-μm-thick samples using Gouy phase shift interferometry is proposed and demonstrated. When the optical path difference (OPD) of the interferometer is zero, destructive interference pattern is produced. In this case, OPD change induced interference signal change is sensitively detected and can be predicted with calculation. By minimizing the difference between the measured and the calculated signal, thickness of a sample can be determined. Thicknesses of sub-100-μm-thick samples are determined with the 5 % accuracy at 625 GHz.

In this paper, we propose a high speed terahertz(THz) imaging system by using hexagonal polygon mirror. The system consists of a single emitter, detector, a hexagonal polygon mirror for scanning, and a telecentric $f-\theta$ lens for imaging. The THz wave from the emitter is two-dimensionally steered by a polygon mirror and irradiated to the object through a telecentric $f-\theta$ lens. The irradiated THz wave is reflected by the object and then returns to the detector in the same path as the optical path illuminated by the telecentric $f-\theta$ lens. In this process, when the THz wave goes out of the lens, the clock mirror extracts the clock signal for the image alignment processing.

A terahertz continuous wave system is demonstrated for thickness measurement using Gouy phase shift interferometry without frequency sweep. One arm of the interferometer utilizes a collimated wave as a reference, and the other arm applies a focused beam for sample investigation. When the optical path difference (OPD) of the arms is zero, a destructive interference pattern is produced. Interference signal intensity changes induced by the OPD changes can be easily predicted by calculations. By minimizing the difference between the measured and the calculated signal against the OPD, the thicknesses of sub-100-μm-thick samples are determined at 625 GHz.

Summary: Early-passage human mesenchymal stem cells (hMSCs) are typically used in clinical trials because of safety and efficacy issues. However, obtaining sufficient cells for treatment is difficult and expensive. Many more late-passage hMSCs can be obtained at lower cost, although efficacy is a large hurdle in clinical trials. The use of late-passage MSCs with better efficacy would be a revolutionary solution for reducing cost and facilitating clinical trials. In the present study, glia-like cells (ghMSCs) were induced from hMSCs and used for both in vitro and in vivo models of ischemia, effectively protecting neurons from ischemia and restoring brain tissue damaged by cerebral infarction. These beneficial effects were significantly blocked by insulin-like growth factor-binding protein-4 (IGFBP-4) antibody. The current study demonstrated that late-passage hMSCs can be efficiently induced into ghMSCs with a better neuroprotective effect against ischemic stroke and that IGFBP-4 may be a key neuronal survival factor secreted by ghMSCs. Funding Statement: This research was supported by a grant from the Korea Health Technology R&D Project through the Korea Health Industry Development Institute (KHIDI), funded by the Ministry of Health & Welfare, Republic of Korea (grant number: HI17C2160). Declaration of Interests: One of the corresponding authors, Mi-Sook Chang, has a patent related to this work, which is noted in the "Declaration of Interests" section of the manuscript. She obtained a Korean patent for glia-like human mesenchymal stem cells in 2012. Ethics Approval Statements: All procedures involving animals were approved by the Institutional Animal Care and Use Committee, Seoul National University (Seoul, Republic of Korea). In addition, all animal procedures were performed in accordance with the Hanyang University guidelines for the care and use of laboratory animals and were approved by the Institutional Animal Care and Use Committee (IACUC) of Hanyang University. In accordance with Animal Research: Reporting of In Vivo Experiments (ARRIVE) guidelines, all experiments were carried out in a strictly blinded fashion, inclusion and exclusion criteria were predetermined, and attrition due to mortality and other causes was reported

We demonstrate on n-InGaAs/n+-InP hetero-epitaxial structure based low-barrier Schottky barrier diode with integrated antenna for broadband THz detection. These devices showed refined and uniform nonlinear rectifying characteristics. Based on this device, a compact and robust hermetic packaged module was fabricated. The developed module showed stable and consistent electrical characteristics even in mechanical/vibration shock and abrupt change of temperature. The detection performance of module was characterized by frequency domain spectroscopy system, and as a result, it had a detectable bandwidth of 0.1–0.8 THz, a voltage responsivity of 320 V/W, and noise equivalent power of 3.1∙10−9 W/Hz0.5 at 300 GHz.

Sexual dysfunction is a common problem after cerebral infarction; however, little is known about sexual arousal in poststroke patients. Thus, this study aimed to investigate brain activation in response to visual sexual stimuli in patients with right middle cerebral artery (MCA) territory infarction using functional magnetic resonance imaging (fMRI). Using fMRI in 20 participants (11 right MCA infarction patients and 9 age-matched healthy controls), we assessed brain activation elicited by visual sexual stimuli (erotic images) and visual nonsexual stimuli (landscape images). In right MCA infarction patients, the left dorsolateral prefrontal cortex and the left frontal subgyral area were more strongly activated by visual sexual stimuli than by nonvisual sexual stimuli. Brain areas that were more activated by visual sexual stimuli in right MCA infarction patients than in controls included the right parahippocampal gyrus and the bilateral frontal subgyral area. These fMRI results suggest that brain activation patterns in response to visual sexual stimuli might be influenced by right MCA infarction. Further research is needed to explore the association between sexual dysfunction and brain activation in poststroke patients.

The incorporation of permeation enhancers in topical preparations has been recognized as a simple and valuable approach to improve the penetration of antifungal agents into toenails. In this study, to improve the toenail delivery of efinaconazole (EFN), a triazole derivative for onychomycosis treatment, topical solutions containing different penetration enhancers were designed, and the permeation profiles were evaluated using bovine hoof models. In an in vitro permeation study in a Franz diffusion cell, hydroalcoholic solutions (HSs) containing lipophilic enhancers, particularly prepared with propylene glycol dicaprylocaprate (Labrafac PG), had 41% higher penetration than the HS base. Moreover, the combination of hydroxypropyl-β-cyclodextrin with Labrafac PG further facilitated the penetration of EFN across the hoof membrane. In addition, this novel topical solution prepared with both lipophilic and hydrophilic enhancers was physicochemically stable, with no drug degradation under ambient conditions (25 °C, for 10 months). Therefore, this HS system can be a promising tool for enhancing the toenail permeability and therapeutic efficacy of EFN.

The present study provides numerical simulations to predict the added resistance and ship motion of the KVLCC2 in regular waves using the unsteady Reynolds-Averaged Navier-Stokes (URANS) and 3-D potential methods. This numerical analysis is focused on added resistance and vertical ship motions (heave and pitch) under a wide range of wave conditions at three ship speeds (design, operating and zero speeds). Firstly, the characteristics of the CFD and 3-D potential flow methods are presented to predict added resistance and ship motions in regular waves taking into account various wave conditions at design speed to provide a validation study as well as at operating and zero speeds. Secondly, analyses of added resistance and ship motion with unsteady wave patterns and time history results as simulated by CFD were performed at each ship speed. Systematic validation and verifications of the numerical computations in this study were made against available Experimental Fluid Dynamics (EFD) data including grid convergence tests to demonstrate that reliable numerical results were obtained for the prediction of added resistance and ship motion in waves. Relationships between added resistance, vertical motion and changes in ship speeds were also found.

We investigated high-field terahertz (THz) responses and the nonlinear conductivities of n- and p-type GaAs thin films in the THz region. As the THz pulse intensity was increased to 59 μJ/cm 2 , the THz transmission of the n-type GaAs thin film was significantly increased, more than that of the p-type film. This result is correlated with the conductivity of the electronic system caused by scattering processes. Intervalley scattering was dominant in n-type GaAs, whereas hot–cold hole interactions and intervalence band transitions were the main factors reducing the conductivity in p-type GaAs. In addition, we extracted the frequency-domain conductivity of the n- and p-type GaAs thin films and used the Drude–Smith model to explain non-Drude-like behavior due to high-field excitation.

Endovascular coil embolization using a balloon- or stent-assisted technique for the treatment of wide-necked posterior communicating artery (PcomA) aneurysms is well established. However, complete aneurysm occlusion with preservation of the PcomA can be difficult in case of wide-neck aneurysms with a PcomA incorporation. We present two cases of stent-assisted coil embolization using a retrograde approach through the posterior circulation for wide-neck or branch-incorporated PcomA aneurysms. Retrograde stenting was successful without periprocedural complications. These aneurysms were completely occluded. The patency of the PcomA was maintained in all cases.

We report magnetic resonance imaging findings of 4 patients with systemic lupus erythematosus who presented with noninfectious meningitis by lupus itself. Magnetic resonance imaging of the brain demonstrated diffuse or localized high-signal intensity in subarachnoid spaces on fluid-attenuated inversion recovery (FLAIR) or postcontrast fluid-attenuated inversion recovery. Cerebrospinal fluid study revealed no abnormalities other than increased level of proteins. Our report is the first description of magnetic resonance findings in context of leptomeningeal involvement in non-infectious meningitis of patients with systemic lupus erythematosus.

To differentiate dural arteriovenous fistula (DAVF) from reflux venous flow (RVF) by assessment of asymmetric enlargement of external carotid artery (ECA) branches on three-dimensional (3D) time-of-flight magnetic resonance angiography (TOF-MRA).Nineteen patients with DAVF and 27 patients with RVF were included from September 2007 to April 2019. The locations of DAVF were the cavernous (n=9) and sigmoid-transverse (n=6) sinuses, and the jugular (n=3) and sphenoparietal (n=1) veins. Two radiologists visually assessed asymmetric enlargement of the ascending pharyngeal artery (ASP), middle meningeal artery (MMA), accessory meningeal artery (AMA), artery of the foramen rotundum, and occipital artery. MMA size was also measured quantitatively.More frequent asymmetric enlargement of the ASP and MMA were seen in DAVF than in RVF (17 of 19 versus 3 of 27 for ASP; 16 of 19 versus 1 of 27 for MMA, p0.01). The AMA, artery of the foramen rotundum, and occipital arteries were not visualised in RVF patients. The ipsilateral MMA size was significantly larger in DAVF than in RVF (2.14 versus 0.64 mmDAVF showed significantly larger ECA branches than RVF on 3D TOF-MRA. Therefore, thorough evaluation of ECA branches could help to differentiate DAVF from RVF.

We developed a visual ranking system by combining the parenchymal perfusion deficits (PPD) and hyperintense vessel signals (HVS) on arterial spin labeling (ASL) imaging. This study aimed to assess the performance of this ranking system by correlating with subtypes classified based on dynamic susceptibility contrast (DSC) imaging for evaluating the perfusion disturbance observed in patients with ischemic stroke. 32 patients with acute or subacute infarcts detected by DSC imaging were reviewed. Each patient's brain was divided into 12 areas. ASL ranks were defined by the presence (+) or absence (-) of PPD/HVS as follows; I:-/-, II:-/+, III: +/+, and IV: +/-. DSC imaging findings were categorized based on cerebral blood flow (CBF) and time to peak (TTP) as normal (normal CBF/TTP), mismatched (normal CBF/delayed TTP), and matched (decreased CBF/delayed TTP). Two reviewers rated perfusion abnormalities in the total of 384 areas. The four ASL ranks correlated well with the DSC subtypes (Spearman's r = 0.82). The performance of ASL ranking system was excellent as indicated by the area under the curve value of 0.94 using either matched or mismatched DSC subtype as the gold standard and 0.97 using only the matched DSC subtype as the gold standard. The two methods were in good-to-excellent agreement (maximum κ-values, 0.86). Inter-observer agreement was excellent (κ-value, 0.98). Although the number of patients was small and the number of dropouts was high, our proposed, ASL-based visual ranking system represented by PPD and HVS provides good, graded estimates of perfusion disturbance that agree well with those obtained by DSC perfusion imaging.

Rectifiers have been used to detect electromagnetic waves with very low photon energies. In these rectifying devices, different methods have been utilized, such as adjusting the bandgap and the doping profile, or utilizing the contact potential of the metal-semiconductor junction to produce current flow depending on the direction of the electric field. In this paper, it is shown that the asymmetric application of nano-electrodes to a metal-semiconductor-metal (MSM) structure can produce such rectification characteristics, and a terahertz (THz) wave detector based on the nano-MSM structure is proposed. Integrated with a receiving antenna, the fabricated device detects THz radiation up to a frequency of 1.5 THz with responsivity and noise equivalent power of 10.8 V/W and [Formula: see text] respectively, estimated at 0.3 THz. The unidirectional current flow is attributed to the thermionic emission of hot carriers accelerated by the locally enhanced THz field at the sharp end of the nano-electrode. This work not only demonstrates a new type of THz detector but also proposes a method for manipulating ultrafast charge-carrier dynamics through the field enhancement of the nano-electrode, which can be applied to ultrafast photonic and electronic devices.

A study on the green ship design for Ultra Large Container Ship (ULCS, 18,000 TEU Class Container Ship) was performed based on the four step procedures of the initial design and hull form optimization to maximize economic and propulsive performance. The first, the design procedure for ULCS was surveyed with economic evaluation considering environmental rules and regulations. The second, the characteristics of single and twin skeg container ships were investigated in view of initial design and performances. The third, the hull form optimization for single and twin skeg ships with the same dimensions was conducted to improve the resistance and propulsive performances at design draught and speed by several variations and the results of the optimization were verified by numerical calculations of CFD and model test. The last, for the estimated operating profile of draught and speed, the hull forms of single and twin sked ships were optimized by CFD. From this study, the methodologies to optimize the hull form of ULCS were proposed with considerations during the green ship design and the improvement of the energy efficiency for the optimized hull forms was confirmed by the proposed formula of the total energy considering design conditions, operating profile and fuel oil consumption.

In vivo tracking of transplanted stem cells has been a central aim of stem cell therapy. Although many tracking systems have been introduced, no method has yet been validated for clinical applications. We developed a novel sophisticated peptide (GV1001) that mimics hTERT (human telomerase reverse transcriptase) and analysed its ability to track and protect stem cells after transplantation. Ferrocenecarboxylic acid-conjugated GV1001 (Fe-GV1001) efficiently penetrated stem cells with no adverse effects. Moreover, Fe-GV1001 improved the viability, proliferation, and migration of stem cells under hypoxia. After Fe-GV1001-labelled stem cells were transplanted into the brains of rats after stroke, the labelled cells were easily tracked by MRI. Our findings indicate that Fe-GV1001 can be used for the in vivo tracking of stem cells after transplantation into the brain and can improve the efficacy of stem cell therapy by sustaining and enhancing stem cell characteristics under disease conditions.

OBJECTIVE To investigate the clinical significance of 4-hour delayed-enhanced 3.0 Tesla three-dimensional (3D) fluid-attenuated inversion recovery (FLAIR) magnetic resonance (MR) imaging in acute vestibular neuritis. STUDY DESIGN A prospective observational study. METHODS Twenty-nine vestibular neuritis patients were enrolled between January 2017 and June 2017. Vestibular function tests, comprising the caloric and video head impulse tests and vestibular-evoked myogenic potential measurements, were performed. Precontrast, 10-minute, and 4-hour delayed-enhanced 3D-FLAIR MR images using double-dose IV gadolinium were obtained. After laterality and extent of inner ear enhancement were defined, the patients were divided into groups based on the patterns of enhancement, and clinical parameters were analyzed according to the groups. RESULTS Twenty patients (20 of 29, 69.0%) had obviously asymmetric enhancement of the affected inner ear structures on 4-hour delayed images, whereas only three patients (10.3%) had marked enhancement on 10-minute delayed images. The duration of spontaneous nystagmus (DurSN) was significantly longer in the patients with enhancement, especially with enhancement of the whole inner ear, including the vestibule and semicircular canals (P

To evaluate the magnetic resonance imaging (MRI) findings of labyrinthine hemorrhage as a cause of sudden sensorineural hearing loss (SSNHL).MRI scans of 59 patients with SSNHL were retrospectively analyzed and compared to clinical features and audiometry data. MR images included pre-enhanced T1-weighted, 3D FLAIR volume isometric turbo spin-echo acquisition (VISTA), post-enhanced T1-weighted and 4-h-delayed enhanced FLAIR VISTA, and 3D thin-section proton density-weighted images.High labyrinth signals were seen on pre-enhanced T1-weighted and 3D FLAIR VISTA images with no enhancement for 6 of 59 (10.2%) patients with SSNHL. In these six patients with presumed inner-ear hemorrhage, high signal intensity was seen in the endolymphatic and perilymphatic portions of the labyrinth on T1-weighted and 3D FLAIR VISTA images. In patients with SSNHL with nonhemorrhagic causes such as vestibular schwannoma or labyrinthitis, high signal or labyrinthine enhancement was seen only in the perilymphatic portion of the labyrinth on pre- or post-enhanced 3D FLAIR VISTA images.MRI using pre-enhanced T1-weighted, 3D FLAIR VISTA, and post-enhanced T1-weighted, 4-h delayed enhanced FLAIR VISTA images is able to identify labyrinthine hemorrhage as the cause of SSNHL. High signals in both the endolymphatic and perilymphatic portions of the labyrinth on pre- or post-enhanced 3D FLAIR VISTA images without enhancement indicate labyrinthine hemorrhage.

By adopting nanoelectrodes, the performances of THz photo-conductive antennas (PCAs) and photomixers (PMs) have been significantly improved. On the extension of our previous works, here we present a nanoelectrode PM for homodyne THz detection, free from low-temperature-grown semiconductors. It was realized by utilizing the electric field enhancement effect by the nanoelectrode, which may be applied to various kinds of optoelectronic devices in general.

Recently, a wide interest has been gathered in using terahertz (THz) waves as the carrier waves for the next generation of broadband wireless communications. Upon this objective, the photonics technologies are very attractive for their usefulness in signal generations, modulations and detections with enhanced bandwidth and data rates, and the readiness in combining to the existing fiber-optic or wireless networks. In this paper, as a preliminary step toward the THz wireless communications, a THz wireless interconnection system with a broadband antenna-integrated uni-traveling-carrier photodiode (UTC-PD) and a Shottky-barrier diode (SBD) module will be presented. In our system, optical beating signals are generated and digitally modulated by the optical intensity modulator driven by a pulse pattern generator (PPG). As the receiver a SBD and an IF filter followed by a low-noise preamplifier and a limiting amplifier was used. With a 6-mA photocurrent of the UTC-PD which corresponds to the transmitter output power of about 30 μW at 280 GHz, an error-free (BER

Terahertz (THz) waves have been actively studied for the applications of astronomy, communications, analytical science and bio-technologies due to their low energy and high frequency. For example, THz systems can carry more information with faster rates than GHz systems. Besides, THz waves can be applied to imaging, sensing, and spectroscopy. Furthermore, THz waves can be used for non-destructive and non-harmful tomography of living objects. In this reasons, Schottky barrier diodes (SBD) have been widely used as a THz detector for their ultrafast carrier transport, high responsivity, high sensitivity, and excellent noise equivalent power. Furthermore, SBD detectors envisage developing THz applications at low cost, excellent capability, and high yield. Since the major concerns in the THz detectors for THz imaging systems are the realizations of the real-time image acquisitions via a reduced acquisition time, rather than the conventional raster scans that obtains an image by pixel-by-pixel acquisitions, a line-scan based systems utilizes an array detector with an 1 × n SBD array is preferable. In this study, we fabricated the InGaAs based SBD array detectors with broadband antennas of log-spiral and square-spiral patterns. To optimize leakage current and ideality factor, the dependence to the doping levels of ohmic and Schottky layers have been investigated. In addition, the dependence to the capacitance and resistance to anode size are also examined as well. As a consequence, the real-time THz imaging with our InGaAs SBD array detector have been successfully obtained.

요 약 : 본 논문의 주 목적은 프루드 수가 0.5 이상인 중형 경비정의 속도성능을 모형시험 이전에 CFD 결과를 바탕으로 기존의 모형시험 자료를 활용하였다. 모형시험 이전에 CFD를 이용하여 선속 별로 추정된 제동마력이 주어진 엔진마력을 만족하는지를 평가 하였다. 대상선박 은 선미가 서로 다른 두 가지 선형을 선정하였다. 점성 유동장 계산은 상용 CFD 코드인 STAR-CCM+를 사용하였으며, 자유수면과 자세 변 화(동적 트림)를 모두 고려하였다. 알몸 선체의 저항 값은 CFD를 이용하여 추정되었다. 점성 유동 해석을 통해 두 가지 선형의 자유수면 파 형, 압력분포, 한계유선 그리고 프로펠러 면에서의 속도분포를 비교하였다. 점성 유동 해석 결과를 바탕으로 두 가지 선형에 대한 유효마력 즉, 저항성능을 평가하였다. 부가물 부착에 따른 저항 증가량과 준추진효율 계수(ETAD, ηD)는 모형시험 자료를 활용하였다. 중형 경비정과 같은 고속선박에 관한 속도성능 추정법이 CFD와 기존 시험자료를 이용하여 개발되었다.

The objective of the This study is to access the speed performance employing the sea trial test and CFD with the our own designed and manufactured one-man boat. The overall design process including hull form design was explained. The sea trial was carried out with a manufactured boat in the clam sea. Brake power at the design speed of a boat through the sea trial was measured as 1680 W. The flow computation was conducted considering free surface and dynamic trim using a commercial CFD code(STAR-CCM+). The result of computation provided the information that residual resistance is bigger than fraction`s at design speed. The total efficiency were predicted based on the sea trial and CFD. The Total efficiency was divided into shaft efficiency and quasi-propulsive efficiency. By using quasi-propulsive efficiency, it becomes possible to predict speed performance of boat in future. The results can provide information regarding hull form design, performance analysis and development of a boat in future.

최근 고유가와 환율변동 등 어려운 시장상황 속에서 해운선사는 선박의 대형화와 고속화를 요구하고 있다. 선사들은 선박의 운용유지비 절감을 우선적으로 요구하고 있으며, 이에 조선소에서는 기술경쟁력 유지를 위한 방안으로 속도성능 향상에 중점을 두고 지속적으로 노력 하고 있다. 본 논문에서는 에너지 절약형 선형개발에 중점을 두고 유동제어 띠를 사용한 선박의 저항성능 향상에 관하여 소개한다. 본 연구는 혹등고래(Humpback Whale)의 배 주위에 있는 기다란 줄 무늬 형상을 응용하여 선체표면에 "오목하고 길게 팬 줄 형상 또는 볼록하고 기다란 줄 형상"(이하, 유동제어 띠라고 함)을 단일로 적용하였다. 현재, 제안된 형상은 특허출원이 되어 있다. 이 형상은 선체표면의 압력분포 변화와 압력강하 현상 등을 효과적으로 제어하는 역할을 한다. 실선 적용 시 장점은 블록조립이 완성된 후에 선체표면에 부가물을 부착하는 종래기술과 비교하여 볼 때 블록제작 단계에서 단면형상을 반영할 수 있다는 점에서 비용을 절약할 수 있다고 판단된다. 【Faced with global agenda of greenhouse abatement program including regulations and $CO_2$ emission trading scheme, shipping companies are enforced to a high level of efficiency in fuel consumption. Accordingly shipbuilding companies worldwide are required to develop fuel-efficient ships which otherwise traditionally consume a great amount of fossil fuels. In this dissertation, relevant to the improvement of fuel efficiency for commercial ships, design methodology through the numerical simulations are intensively described. This work consists of derivation of effective hydrodynamic design practice based on the application of longitudinal grooves to effectively improve the pressure distribution around ship hull. The primary objective of the present study is to improve ship resistance performance using longitudinal grooves which originate from long strips on the abdomen of humpback whale. Several groove shapes have been extensively investigated and the proposed shape efficiently controlled the variation of pressure distributions acting on the hull surface.】

The current work investigated the variation of numerical solutions according to the grid number, the distance of the first grid point off the ship surface, turbulence modeling and discretization. The subject vessel is KVLCC. A commercial code, Gridgen V15 and FLUENT were used the generation of the ship hull surface and spatial system and flow computation. The first part of examination, the effect of solutions were accessed depending on the grid number, turbulence modeling and discretization. The second part was focus on the suitable selection of the distance of the first grid point off the ship surface: YP+. When grid number and discretization were fixed the same value, the friction resistance showed differences within 1 % but the pressure resistance showed big differences 9 % depending on the turbulence modeling. When YP+ were set 30 and 50 for the same discretization, friction resistance showed almost same results within 1 % according to the turbulence modeling. However, when YP+ were fixed 100, friction resistance showed more differences of 3 % compared to YP+ of 30 and 50. Whereas pressure resistance showed big differences of 10 % regardless of turbulence modeling. When turbulence modeling and discretization were set the same value, friction, pressure and total resistance showed almost same result within 0.3 % depending on the grid number. Lastly, When turbulence modeling and discretization were fixed the same value, the friction resistance showed differences within 5~8 % but the pressure resistance showed small differences depending on the YP+.

Grape pruning stems constitute a scarcely investigated class of byproducts with limited reports on their bioactive polyphenol content and/or industrial applications. Herein we present the outcome of our investigation on grape pruning stems extracts, concerning the assessment of their total polyphenolic content and the detailed evaluation of their antioxidant properties. Results obtained indicate that grape pruning stems are particularly rich in flavonoids and trans-resveratrol. The antioxidant activities was analyzed and expressed as electron donating ability, ABTS cation radical decolorization, hydrogen peroxide scavenging activity and superoxide anion radical scavenging activity, the antioxidant activity of Vitis labrusca L. pruning stems extracted (GPSE) was higher than that of BHA and L-ascrobic acid. The whitening and anti-wrinkle activities display an capability. Results herein grape pruning stems used as a valuable resource for the extraction of resveratrol, which would be added to functional cosmetics and food materials.

Division of Naval Architecture & Ocean Engineering, Tongmyong University, Busan, 608-711, Korea 요 약 : 일반상선 중 액화천연가스(LNG) 재기화 선박은 기존의 LNG 운반선에 액화된 LNG를 다시 기화할 수 있는 추가설비를 갖춘 선박이다. 이 선박은 해상에서 천연가스를 해저 터미널을 통해 이송하는 수중 터렛 시스템을 보유한다. 하역작업을 완료한 선박이 운항 시에는 수중 터렛이 없음으로 인해 선수부 바닥이 열려 있는 개구부 즉, 오프닝 상태가 발생한다. 본 연구의 주 목적은 오프닝 상태로 운항 시 발생되는 속도손실을 CFD를 이용한 유동해석과 예인수조에서의 모형시험을 통하여 정확하게 파악하였다. 모형시험에서는 나선 상태와 오프닝 상태에서 저항 및 자항성능을 평가하였다. 실험에서는 터프트 법에 의한 유선조사시험을 이용하여 오프닝 내부유동의 변화를 정량적 또는 정성적으로 보다 더 상세한 조사를 하였다.핵심용어 : 액화천연가스 재기화 선박, 개구부, 전산유체역학, 모형시험, 유동 가시화Abstract : LNG-RV has the additional equipments that enable to re-gastify liquefied LNG in LNG carrier. This vessel has Submerged Turret Loading(STL) system which transports gas through submarine terminal. When LNG-RV is operating at sea, the opening condition is formed by detaching STL equipment from a vessel. The primary objective of the current work is to estimate accurate speed loss for the opening condition of the LNG-RV employing numerical calculations and model tests. In the model tests, resistance and self-propulsion tests are carried out for the bare-hull and the opening condition without STL. In addition to these, flow visualization utilizing tuft is used to make the flow patterns visible, in order to get a qualitative or quantitative information for inner part in case of detaching the STL.Key Words : LNG-RV, Opening condition, CFD, Model test, Flow visualization

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The primary objective of the current work is to obviously analyze regarding effects of trim conditions of a ship on resistance performance using model test and CFD. Model tests at a towing tank are conducted to investigate resistance for trim conditions at the given same displacement. Measured resistance shows small but distinct differences according to trim conditions. However, these differences are difficult to be clarified by measured physical quantities and wave pattern analysis from model tests. CFD is employed for the assessment of resistance performance according to trim conditions. The flow computation is conducted considering free surface and dynamic trim using a commercial CFD code (STAR-CCM+). The initiative of the present work is to systematically demonstrate pressure resistance acting on each region of divided finite zones of ship surface along the length and draught direction of surface when pressure distribution on the ship is interpreted. Also, a standard to assess the pressure resistance applied on the divided regions of a ship is established.

* Department of Naval Ardchitecture & Ocean Engineering, Chonnam National University, Yeosu 550-749, Korea†Maritime Research Institute, Hyundai Heavy Institute, Ulsan 682-792, Korea요 약 :본 연구에서는 개발된 선미부에 수직날개를 부착한 선박의 조파저항성능을 예측할 수 있는 수치해석기법의 검증에 관한 것이다. 수치해석기법은 비점성 유동장 해석기법인 랜킨소오스 패널법과 와류격자법을 사용하여 개발하였으며, 자유수면 경계조건의 비선형성은 반복해법을 사용하여 만족시켰고, 선박의 트림과 침하량을 구하는 알고리즘을 포함하고 있다. 수치해석을 위한 선체표면의 패널을 생성하기 위하여 패널절단법을 사용하였다. 4000TEU 컨테이너 운반선을 대상 선박으로 하여 선미부 6개소의 서로 다른 위치에 수직날개를 부착하여 수치해석을 수행하였으며, 수치해석기법의 타당성을 검증하기 위하여 상용 점성 유동장 해석 프로그램인 FLUENT를 사용하여 선체 주위의 점성 유동장을 계산하였고, 모형시험을 수행하여 얻은 실험 결과를 수치해석 결과와 서로 비교하였다. 핵심용어 : 수직날개, 조파저항성능, 랜킨소오스 패널법, 와류격자법, 모형실험, 패널절단법Abstract : In this paper the developed prediction technique of wave-making resistance performance for a ship attached with a vertical blade had been verified. Numerical analysis program as a prediction technique had been developed using the Rankine source panel method and the vortex lattice method(VLM). The nonlinearity of the free surface conditions was fully taken into account using the iterative method and the trim and the sinkage of the ship were also considered in the numerical analysis program. Panel cutting method was applied to get hull surface panels. Numerical computations were carried out for a 4000TEU container carrier and the vertical blade was attached 6 different locations astern. To investigate the validity of the numerical analysis program the commercial viscous flow field analysis program FLUENT was used to obtain the viscous flow field around the ship and the model test was performed. The model test results were compared with the numerical analysis results.Key words :Vertical Blade, Wave-making resistance performance, Rankine source panel method, Vortex lattice method, Model test, Panel cutting method†교신저자 : 정회원, dwpark@hhi.co.kr 052) 202-5861* 정회원, choihj@jnu.ac.kr 061) 659-7154

A design procedure for a ship with minimum resistance had been developed using a numerical op-timization method called SQP (Sequential Quadratic Programming) combined with computational fluid dynamics (CFD) technique. The frictional resistance coefficient was estimated by the ITTC 1957 model-ship correlation line formula and the wave-making resistance coefficient was evaluated by the potential-flow panel method with the nonlinear free surface boundary conditions. The geometry of the hull surface was represented and modified by B-spline surface modeling technique during the optimi-zation process. The Series 60 (C B =0.60) hull was selected as a parent hull to obtain an optimized hull that produces minimum resistance. The models of the parent and optimized hull forms were tested at calm water condition in order to demonstrate the validity of the proposed methodolgy. Keywords: Hull optimization, Minimum resistance, Ranking source panel method, SQP(Sequential Quadratic Programming), B-spline surface modeling