• Journal of Ocean Engineering and Technology
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• v.25 no.2
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• pp.92-100
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• 2011

The main goal of this paper is to provide the theoretical background for the fracture phenomena in marine structural steels. In this paper, various fracture criteria are theoretically investigated: shear failure criteria with constant failure strain and stress triaxiality-dependent failure strain (piecewise failure and Johnson-Cook criteria), forming limit curve failure criterion, micromechanical porosity failure criterion, and continuum damage mechanics failure criterion. It is obvious that stress triaxiality is a very important index to determine the failure phenomenon for ductile materials. Assuming a piecewise failure strain curve as a function of stress triaxiality, the numerical results coincide well with the test results for smooth and notched specimens, where low and high stress triaxialities are observed. Therefore, it is proved that a failure criterion with reliable material constants presents a plastic deformation process, as well as fracture initiation and evolution.

• Journal of the Korean Society of Food Science and Nutrition
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• v.27 no.3
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• pp.531-536
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• 1998

To investigate effects of Angelica keiskei Koidz green juice on the liver damage of CCl4-treated tats, Sprague-Dawley male rats weighing 80~100g were divided into 4 groups of control group(CON), Angelica keiskei Koidz green juice-treated group(ANJ), CCl4-treated group(CCL) and Angelica keiskei Kodiz green juice and CCl4-treated group(ACL). Each group was sacrified after feeding for 4 weeks and examined the activities of transminase (sGOT, sGPT), superoxide dismutase (SOD), catalase and glutathione peroxidase(GSH-Px), and contents of lipid peroxide and glutathione in liver. The activities of sGOT and sGPT, and content of lipid peroxide after CCl4 treatment were markedly increased, compared to CON, but those levels were significantly decreased by the pretreatment of Angelica keiskei Koidz green juice as compared to CCL. The activities of SOD, catalase and GSH-Px were elevated by CCl4-treatment as compared to control group, and concomitant treatment of Angelical keiskei Koidz and CCl4 decreased those levels significantly except the activity of catalase. The hepatic content of glutathione was decreased by CCl4 and increased more abundant by Angelica keiskei Koidz administration than CCl4 treated group. These results suggest that Angelica keiskei Koidz green juice is believed to have a possible protective effect for the carbon tetrachloride-induced hepatotoxicity in rats.

• Journal of Physiology & Pathology in Korean Medicine
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• v.16 no.6
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• pp.1207-1210
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• 2002

To examine the cardiotoxic effect of adriamycin on cultured rat myocardial cells, cytotoxicity was measured by MTT assay after cultured myocardial cells were grown with various concentrations of adriamycin(ADA) for 48 hours. The protective effect of Benincasae Semen(BS) on ADR-induced cardiotoxicity was also examined in these cultures. ADR decreased cell viability of cultured rat myocardial cells remarkably in a dose- and time-dependent manners. In protective effect of BS, it was very effective in blocking ADR-induced cytotoxicity. From these results, it is suggested that ADR shows cardioxicity, and the herba extract, as is very effective in preventing ADR-induced cytotoxicity on cultured rat myocardial cells.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.34 no.7
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• pp.843-850
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• 2010

A spacer grid assembly is one of the most important structural components of the nuclear fuel assembly of a Pressurized Water Reactor (PWR). A primary design requirement is that the fuel rod integrity be maintained by the spacer grid assembly during the operation of the reactor. In this study, we suggested a new spacer grid assembly having a fuel rod support, which is capable of sliding when the fuel rod vibrates due to flow-induced vibrations in the reactor. By adjusting the relative displacement between the fuel rod and its support, the proposed design will help in reducing fuel rod fretting damage.

• Proceedings of the Korean Vacuum Society Conference
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• 2010.08a
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• pp.227-227
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• 2010

기존 실리콘 박막 태양 전지는 적외선에 대한 감응도와 흡수도가 낮아서 광흡수율을 증가시킬 경우 효율의 효과적인 개선이 기대되어진다. 이를 개선하기 위해서 밴드갭이 Si에 비해 상대적으로 낮은 Ge을 도입함으로써 Si와 Ge 화합물을 형성할 경우 결정상태와 수소 함유량에 따라 밴드갭 조절이 가능하다. 또한 Ge는 Si에 비해 빛에 대한 감응도가 우수하여 광흡수율을 증가시킬수 있다. 단 SiGe 박막의 Ge 량이 일정량이상 많아질 경우 박막 내 결함 등의 생성으로 광변환 효율이 오히려 감소하므로 Ge 량의 적정화가 필요하다. 본 실험에 사용된 SiGe:H Layer는 $SiH_4$ 가스와 $GeH_4$ 가스를 혼합하여 증착하였고 증착두께는 150nm로 고정하였으며 증착장비는 PECVD를 이용하였다. 파워는 플라즈마의 방전특성을 알아본 후 최소파워를 이용하여 증착하였다. 이는 증착 시 플라즈마에 의한 박막 손상을 최소화하기 위함이다. Ellipsometry를 이용하여 박막의 두께와 optical bandgap을 측정하였다. 박막의 특성을 평가하기 위해서 STA 장비를 이용하여 dark conductivity, photo conductivity, activation energy 등을 측정하였고, MDC를 이용해 C-V 곡선을 측정하였고, 이를 terman method를 이용하여 $D_{it}$를 계산하였다.

• Korean Journal of Organic Agriculture
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• v.9 no.3
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• pp.45-71
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• 2001

The duck-rice forming system is increasingly spread up throughout Korea since 1992. It is discussed the rice field, rice quality, weed and pest management in the duck-rice weeding system compared to conventional farming system. Moreover the optimizing duck population, system management and fertilizer application rate were reported. Energy input and output by duck-rice farming system were carefully compared with those of low input sustainable paddy field and conventional farming paddy field. To find out the environmentally sound function of duck-rice system, the total nitrogen in paddy soil and paddy water, and nitrogen cycle in paddy rice cultivation system were analysed. finally the input and output were calculated, and ecological characteristic were determined in terms of nitrogen balance, labor input, animal input, renewable energy input, turnover of soil organic matter, energy loss, non-renewable indirect and direct energy input. It was concluded duck-rice weeding system could be recommended in terms of net only environmentally sound, but also farmer's income. But there are still some research needs for successful adaption of duck-rice farming to investigate to determine the optimal population of duck in rice paddy field unit, release time of duckling, duck management after release, and strategy for duck marketing and duck processing.

• Proceedings of the Korean Vacuum Society Conference
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• 2011.02a
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• pp.165-165
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• 2011

기존 실리콘 박막 태양 전지는 적외선에 대한 감응도와 흡수도가 낮아서 광흡수율을 증가시킬 경우 효율의 효과적인 개선이 기대되어진다. 이를 개선하기 위해서 밴드갭이 Si에 비해 상대적으로 낮은 Ge을 도입함으로써 Si와 Ge 화합물을 형성할 경우 결정상태와 수소 함유량에 따라 밴드갭 조절이 가능하다. 또한 Ge는 Si에 비해 빛에 대한 감응도가 우수하여 광흡수율을 증가시킬수 있다. 단 SiGe 박막의 Ge 량이 일정량이상 많아질 경우 박막 내 결함 등의 생성으로 광변환 효율이 오히려 감소하므로 Ge 량의 적정화가 필요하다. 본 실험에 사용된 SiGe:H Layer는 SiH4 가스와 GeH4 가스를 혼합하여 증착하였고 증착장비는 PECVD를 이용하였다. GeH4/SiH4+GeH4 가스는 각각 0, 0.03, 0.1, 0.5, 1의 비율로 증착하였으며, 파워는 플라즈마의 방전특성을 알아본 후 최소파워를 이용하여 증착하였다. 이는 증착 시 플라즈마에 의한 박막 손상을 최소화하기 위함이다. Ellipsometry를 이용하여 박막의 두께와 optical bandgap을 측정하였고, FTIR, Raman scattering 등을 측정하였다.

• The Journal of Churna Manual Medicine for Spine and Nerves
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• v.5 no.1
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• pp.81-89
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• 2010

Objects : This study was to report a clinical effect of Chuna Treatment for a patient diagnosed by Magnetic Resonance Imaging(MRI) as Cervical Myelopathy. Methods: In order to alleviate shoulder pain and neck stiffness, the patient was treated by acupuncture therapy, herbal medicine, phamacopucture, cervical traction technique of Chuna treatment and conservative managements. To evaluate the effect of the treatment, Recovery rate of Hirabayashi, VAS(Visual Anlaogue Scale), NDI and ROM(Range of Motion) were used. Lhermitte's sign, Valsalva test, Distraction test, Compression test and Spurling test were carried out. Results: VAS, NDI and ROM were improved and Recovery rate was 100%. Conclusions: Korean Treatment can be effectively used for a patient with Cervical Myelopathy. Further clinical studies are needed to verify the findings.

• Journal of the Society of Naval Architects of Korea
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• v.47 no.6
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• pp.813-820
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• 2010

The spread mooring system for FPSO is developed to explore deep sea area, in which swell is dominant. It is known that the tension response of mooring lines in this sea area shows bimodal spectrum. Assuming normal distribution of tension profile and Rayleigh distribution of tension amplitude, the power spectral density function (PSD) of the mooring tension under the bimodal stationary random process is applied for the calculation of spectrum fatigue. Three popular methods, which are simple summation method, combined spectrum method and Jioa-Moan method, are used to combine fatigue damages from bimodal spectrum characteristics. Each damage value is compared with damage using Rainflow Cycle Counting (RCC) method which is believed to be close to exact solution. Vanmarcke' parameter and RMS(Root Mean Square) ratio are employed to assess relative damage variations between from RCC method and from three combination methods. Finally the most reliable fatigue damage combining method for spread mooring system is suggested.

• Proceedings of the KIPE Conference
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• 2001.07a
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• pp.464-466
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• 2001

The advantage of the squirrel cage induction motor is the brushless rotor. This advantage for operation and maintenance turns out to be a disadvantage for the detection of the cage rotor bar and endring defects, which means that the detection of cage faults is due to the measurement and analysis of only the stator input signals. The monitoring task in an inverter drive is complicated mainly because the voltage and current waveforms are nonsinusoidal and the high dv/dt values from fast switching inverterd distort the measurements. in this paper, we are going to discuss the detection method of broken rotor bar of squirrel cage induction motor by the motor current signal analysis(MCSA).