• 한국해양학회지
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• v.21 no.4
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• pp.245-258
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• 1986

A two-dimensional numerical model is developed to investigate the phenomenon of forced seiche caused by the incident long waves. This model is applied to Young-il Bay and Pohang New Harbor, where the seiche is most frequently observed and the damage of the seiche is serious compared with the other harbors in Korea. Some results on this study are as follows; 1. The natural periods of the first two modes obtained from the present model are about 70 and 25 minutes respectively for Young-il Bay, and about 25 and 7.5 minutes for Pohang New Harbor. These results are well consistent with those obtained by the theoretical formula, the spectral analysis, and the statistical investigation of the recorded data. 2. Since the fundamental natural period of Pohang New Harbor is almost the same as the second natural period of Young-il Bay, the seiche in Pohang New Harbor can be strongly amplified by the Oscillation in Young-il Bay. Therefore, the most strong seiche in Pohang New Harbor can occur when the long wave of about 25-minute period come into Young-il Bay.

• Journal of Korea Water Resources Association
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• v.37 no.6
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• pp.461-466
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• 2004

This study presents a combined experimental and numerical effort to investigate wave breaking of sinusoidal waves in a surf zone. Numerical predictions are verified by comparing to laboratory measurements. The model solves the Reynolds equations and$textsc{k}$-$\varepsilon$ models for the turbulence analysis. To track the free surface displacement, the volume of fluid method is employed. As the height of incident wave increases, the wave breaking occurs at a closer point of the slope in the numerical model and laboratory experiments with the same depth and period. When a wave breaking occurs, the ratio of wave height becomes larger, with the same wave height and depth, as the period increases.

• Proceedings of the Korean Vacuum Society Conference
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• 2012.02a
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• pp.144-144
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• 2012

최근 폴리머를 기판으로 하는 고속 Flexible TFT (Thin film transistor)나 고효율의 박막 태양전지(Thin film solar cell)를 실현시키기 위해 낮은 비저항(resistivity)을 가지며, 높은 홀 속도(carrier hall mobility)와 긴 이동거리를 가지는 다결정 반도체 박막(poly-crystalline semiconductor thin film)을 만들고자 하고 있다. 지금까지 다결정 박막 반도체를 만들기 위해서는 비교적 높은 온도에서 장시간의 열처리가 필요했으며, 이는 폴리머 기판의 문제점을 야기시킬 뿐 아니라 공정시간이 길다는 단점이 있었다. 이에 반도체 박막의 재결정화 온도를 낮추어 주는 metal (Al, Ni, Co, Cu, Ag, Pd, etc.)을 이용하여 결정화시키는 방법(MIC)이 많이 연구되어지고 있지만, 이 또한 재결정화가 이루어진 반도체 박막 안에 잔류 금속(residual metal)이 존재하게 되어 비저항을 높이고, 홀 속도와 이동거리를 감소시키는 단점이 있다. 이에 본 실험은, 종래의 MIC 결정화 방법에서 이용되어진 금속 증착막을 이용하는 대신, HIPIMS (High power impulse magnetron sputtering)와 PIII&D (Plasma immersion ion implantation and deposition) 공정을 복합시킨 방법으로 적은 양의 알루미늄을 이온주입함으로써 재결정화 온도를 낮추었을 뿐 아니라, 잔류하는 금속의 양도 매우 적은 다결정 반도체 박막을 만들 수 있었다. 분석 장비로는 박막의 결정화도를 측정하기 위해 GIXRD (Glazing incident x-ray diffraction analysis)와 Raman 분광분석법을 사용하였고, 잔류하는 금속의 양과 화학적 결합 상태를 알아보기 위해 XPS (X-ray photoelectron spectroscopy)를 통한 분석을 하였다. 또한, 표면 상태와 막의 성장 상태를 확인하기 위하여 HRTEM(High resolution transmission electron microscopy)를 통하여 관찰하였다.

• Korean Journal of Materials Research
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• v.13 no.6
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• pp.389-393
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• 2003

The effect of antireflection layer on the reduction of optical loss has been investigated in Si photodiodes detecting red light with central wavelength of 670 nm. The theoretical analysis showed minimum reflection loss of 6% for the $SiO_2$thickness of about $1100∼1200\AA$ in the $SiO_2$-Si system with the single antireflection layer and no reflection loss for the X$N_3$N$_4$$SiO_2$thickness of $2000\AA$/$1200\AA$ in the $Si_3$$N_4$$SiO_2$-Si system with double antireflection layer. In our experiments, Si photodiodes with the web-patterned $p^{＋}$-shallow diffusion region were fabricated by bipolar IC process technology and the devices were classified into three kinds according to the structure of $Si_3$$N_4$/$SiO_2$antireflection layer. The fabricated devices showed maximum spectral response in the optical spectrum of 650∼700 nm. The average photocurrents of the devices with the $Si_3$$N_4$$SiO_2$thickness of $1000\AA$/X$SiO\AA$, and $2000\AA$$1800\AA$ under the incident power, of -17 dBm were 3.2 uA, 3.5 uA and 3.1 uA, respectively.

• The Korean Journal of Food And Nutrition
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• v.31 no.2
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• pp.252-257
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• 2018

It is noted that Dioscorea quinqueloba is a medicinal herb that is widely used to treat cardiovascular disease and is assessed as useful to treat other various medical conditions. The immunopotentiating effects of the protein extract (DQP-1) from Dioscorea quinqueloba were thus formally investigated in vivo under incident of cold stress. In this case study, the spleen and thymus weight in mice was shown to have decreased after a measured exposure to cold stress, while the adrenal gland weight in the mice was shown to have increased. The systematic oral administration of DQP-1 significantly recovered the weight loss of the spleen and suppressed the adrenal gland hypertrophy during the association with cold stress. Additionally, the DQP-1 also restored the ascorbic acid level in the adrenal gland reduced after cold stress. The cold stress exposure lowered the percentage of $CD4^+$ and $CD8^+$ cells in the mouse thymus as determined by the flow cytometric analysis, as well as the levels of some serum immunological cytokines(interleukin-2, interleukin-12, and interferon-${\gamma}$) in the studied mice. The resulting identified weakened immunity caused by cold stress was also recovered by a treatment with DQP-1. The DQP-1 significantly suppressed the formation of serum enzymes of alanine aminotransferase, aspartate aminotransferase, and lactate dehydrogenase, which were systematically elevated during the cold stress episode. These results indicate that DQP-1 can improve immunity in mice that are characteristically weakened under stress.

• Journal of the Korean housing association
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• v.20 no.2
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• pp.77-86
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• 2009

The purpose of this study was to examine the household characteristics, the actual residential environment of the elderly living with their offsprings together in Gwangju. We also evaluated their satisfaction with the needs for remodeling of their houses and the different opinions about those things between the elderly and their off springs. We used comparative and descriptive T-test in statistical analysis. The results were as follows. There were more families living in the detached houses than those living in the apartments. The average size of the houses was 100.8 square meters. The mean residence period was 13.5 years. The sons were usually the legal householders. The residents who experienced remodeling before reassigned the furniture and installed the bathtub, which was designed to be sat on comfortably in a common. A few residents installed safety system such as alarms for incident fire or gas, convenient knobs for handling and faucets for running hot or cold water separately. After the installation of alarms, convenient knobs of windows or door, Customer satisfaction for those things were quite high. But that for the installation of safety bar were the lowest in contrast. The most things the old wanted to change were to rearrange bedrooms and bathrooms on the first floor and to decorate them in westernized styles. They didn't need to set up safety bars or shower instrument for modulating heights. The second generation wanted to install the blinds or curtains more than the third generations.

• Journal of Korean Association for Spatial Structures
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• v.10 no.1
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• pp.127-134
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• 2010

The dynamic instability for snapping phenomena has been studied by many researchers. Few paper deal with the dynamic bucking under the load with periodic characteristics, and the behavior under periodic excitation is expected the different behavior against STEP excitation. We investigate the fundamental mechanisms of dynamic instability when shallow EP(Elliptic Paraboliodal) shell of two degree of freedom are subjected to sinusoidal excitation with direct snapping and indirect snapping. By using Newmark-$\beta$ method, we can get the nonlinear response, and characteristics of the dynamic instability through the running response spectrum by FFT(fast Fourier Transform) and attractors are compared in the phase plane. Dynamic buckling loads are strongly influenced by the relationships between the natural frequency of structures and the dominant frequency of incident excitations.

• Journal of The Korean Astronomical Society
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• v.29 no.2
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• pp.245-253
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• 1996

We have analyzed infrared (IR) images of Jupiter which was observed at the McDonald Observatory, Texas, U.S.A., during the P/SHoemaker-LEvy 9 (SL9) impact period and about one week after the last impact. The IR images were obtained on the 2.7m telescope using a NICMOS array with filters to isolate the $1.5{\mu}m\;NH_3\; band,\;the\;2.3{\mu}m\;CH_4\;band,\;the\;2.12{\mu}m\;H_2\;S(0)$ pressure-induced absorption, and the continua at $1.58{\mu}m\;and\;2.0{\mu}m$ (short K-band). All images except those with the $1.58{\mu}m$ continuum filter show bright impact sites against the relatively dark Jovian disk near the impact latitude of about $45^{\circ}$ S. This implies that dusts originated from the impacts reflect the solar radiation at high altitudes before absorbed by stratospheric $CH_4,\;NH_3 \;or\;H_2$. The impact sites observed with the $2.3{\mu}m$ filter are conspicuously bright against a very dark background. The morphology of impact sites, G, L, and H at 2.3 and $2.12{\mu}m$ filters shows clearly an asymmetric structure toward the incident direction of the comet fragments, in agreement with the studies of visible impact images obtained with the Hubble Space Telescope. Comparisons of reflectances of G, L, and H sites with simple radiative transfer models suggest that optically thick dust layers were formed at high altitudes at which methane absorption attenuates incoming sunlight only by about $1\%$. The dust layers in these sites seem to form at about the same altitude regardless of the magnitude of the impacts, but they appear to descend gradually after the impacts. The dust layers have optical depths of 2-5, according to the models.

• Nuclear Engineering and Technology
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• v.30 no.5
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• pp.403-415
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• 1998

The CANDU 6 reactor assembly consists of an array of 380 pressure tubes, which are installed horizontally in a large cylindrical vessel, the Calandria, containing the low pressure heavy water moderator. The pressure tube is located inside the calandria tube and the annulus between these tubes, which forms a closed loop with $CO_2$ gas recirculating, is called the Annulus Gas System(AGS). It is designed to give an alarm to the operator even for a small pressure tube leak by a very sensitive dew point meter so that he can take a preventive action for the pressure tube rupture incident. To judge whether the operator action time is enough or not in the design of Wolsong 2,3 & 4, the Leak Before Break(LBB) assessment is required for the analysis of the pressure tube failure accident. In order to provide the required data for the LBB assessment of Wolsong Units 2, 3, 4, a series of leak detection capability tests was performed by injecting controlled rates of heavy water vapour. The data of increased dew point and rates of rise were measured to determine the alarm set point for the dew point rate of rise of Wolsong Unit 2. It was found that the response of the dew point depends on the moisture injection rate, $CO_2$ gas flow rate and the leak location. The test showed that CANDU 6 AGS can detect the very small leaks less than few g/hr and dew point rate of rise alarm can be the most reliable alarm signal to warn the operator. Considering the present results, the first response time of dew point to the AGS $CO_2$ flow rate is approximated.

• Nuclear Engineering and Technology
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• v.41 no.4
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• pp.531-544
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• 2009

This paper is intended to provide key issues and current research outcomes on accelerator-based Boron Neutron Capture Therapy (BNCT). Accelerator-based neutron sources are efficient to provide epithermal neutron beams for BNCT; hence, much research, worldwide, has focused on the development of components crucial for its realization: neutron-producing targets and cooling equipment, beam-shaping assemblies, and treatment planning systems. Proton beams of 2.5 MeV incident on lithium target results in high yield of neutrons at relatively low energies. Cooling equipment based on submerged jet impingement and micro-channels provide for viable heat removal options. Insofar as beam-shaping assemblies are concerned, moderators containing fluorine or magnesium have the best performance in terms of neutron accumulation in the epithermal energy range during the slowing-down from the high energies. NCT_Plan and SERA systems, which are popular dose distribution analysis tools for BNCT, contain all the required features (i.e., image reconstruction, dose calculations, etc.). However, detailed studies of these systems remain to be done for accurate dose evaluation. Advanced research centered on accelerator-based BNCT is active in Korea as evidenced by the latest research at Hanyang University. There, a new target system and a beam-shaping assembly have been constructed. The performance of these components has been evaluated through comparisons of experimental measurements with simulations. In addition, a new patient-specific treatment planning system, BTPS, has been developed to calculate the deposited dose and radiation flux in human tissue. It is based on MCNPX, and it facilitates BNCT efficient planning based via a user-friendly Graphical User Interface (GUI).