• 한국운동역학회지
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• 제22권1호
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• pp.55-63
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• 2012

The purpose of this study was to investigate the balance differences between skilled players and less-skilled players during Hakdariseogi motion of Keumgang Poomsae in Taekwondo. To achieve the study goal, total of 10 Taekwondo athletes; 5 skilled players(S, body mass: $67.0{\pm}5.7$ kg, height: $174.0{\pm}4.8$ cm, age: $20.0{\pm}2.0$ yrs) and 5 less-skilled players(LS, body mass: $73.0{\pm}4.9$ kg, height: $176.4{\pm}6.1$ cm, age: $20.8{\pm}1.3$ yrs) participated in this study. A three-dimensional motion analysis with 8 infrared cameras and one force plate whose sampling frequency as 30 Hz and 300 Hz, respectively, were performed. Participants' motion were divided into three phases which were preparation phase(P1), performing phase(P2) and maintaining phase(P3). The range and velocities of COP, the range and RMS of ground reaction torque and displacement between COM and center of BOS of each phase were computed. In this study, at P1 and P3 which were double and single stance, respectively, the range and M-L velocities of COP revealed significantly higher in LS compared with those of S(p<.05). At P2 which was single stance, LS indicated significantly higher in range of COP and ground reaction torque, and M-L velocities of COP than those of S(p<.05). The significantly shorter displacement between COM and center of BOS, however, was found in LS compared with that of S(p<.05). The results from our study indicated that S revealed more stable performance and a better posture control ability during performing Hakdariseogi motion.

• 한국자동차공학회논문집
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• 제4권6호
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• pp.39-51
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• 1996

In the turning maneuver of the vehicle, its motion is mainly dependent on the genuine steering characteristics in view of the directional stability for stable turning ability. The under steer vehicle has an ability to maintain its own directonal performance for unknown external disturbances to some extent. From a few years ago, in order to acquire the more enhanced handling performance, some types of four wheel steering vehicle were considered and constructed. And, various rear wheel control logics for external disturbances has not been suggested. For this reason, in this posed rear wheel control logic is based on the yaw rate feed back type and is slightly modified by an yaw rate tuning factor for more stable turning performance. And an external disturbance is defined as a motivation of the additional yaw rate in the center of gravity by an uncertain input. In this study, an external disturbance is applied to the vehicle as a form of the additional yawing moment. Finally, the proposed rear wheel control logic is tested on the multi-body analysis software(ADAMS). J-turn and double lane change test are performed for the validation of the control logic.

• 한국안전학회지
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• 제29권5호
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• pp.7-14
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• 2014

This study aimed to develop members with the optimum impact characteristics to ensure a protected space for passengers in the case of automobile collisions. Accordingly, these members were fabricated to provide sufficient rigidity and safety to the passenger room structure and to absorb large amounts of energy during collision. In particular, CFRP members were fabricated with different section shapes such as square and single- and double-hat shapes. Next, their impact collapse characteristics and collapse modes were quantitatively analyzed according to the changes in section shapes and stacking angles. This analysis was performed to obtain design data that can be applied in the development of optimum lightweight members for automobiles.

• 대한본초학회지
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• 제27권4호
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• pp.17-23
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• 2012

Objectives : Schisandrae Fructus (SF) has traditionally been used to balance level of body fluid and to strengthen kidney function. It has been reported that the SF extract has antioxidant, hepatoprotective, neuroprotective and anticancer effects. This study investigated an antiproliferative effect of SF extract on PC-3 human prostate cancer cells and analyzed active ingredients of SF extract qualitatively and quantitatively. Methods : We examined the antiproliferative effect of SF extract with MTT assay, DAPI staining and annexin-V/7-AAD double staining. The active ingredients of SF extract were identified by using HPTLC and HPLC/DAD system. Results : SF-chloroform fraction inhibited growth of PC-3 cells and changed the morphology of nucleus in a dose dependent manner. A dose-dependent apoptotic cell death was also measured by flow cytometry analysis. It was analyzed that SF-chloroform fraction contained more schizandrin than other fractions by using HPTLC and HPLC/DAD system. Conclusions : These results suggest that SF extract and schizandrin may be a potential chemotherapeutic agent for the control of PC-3 human prostate cancer cells.

• 대한전자공학회논문지SD
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• 제44권7호통권361호
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• pp.16-23
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• 2007

본 논문에서는 완전 공핍된 SOI형 대칭 이중게이트 MOSFET의 문턱 전압에 대한 간단한 해석적 모델을 제시하고자 실리콘 몸체 내의 전위 분포를 근사적으로 채널에 수직한 방향의 좌표에 대해 4차 다항식으로 가정하였다. 이로써 2차원 포아송 방정식을 풀어 표면 전위의 표현식을 도출하고, 이 결과로부터 드레인 전압 변화에 의한 문턱 전압의 roll-off를 비교적 정확하게 기술할 수 있는 문턱 전압의 표현식을 closed-form의 간단한 표현식으로 도출하였다. 도출된 표현식으로 모의 실험을 수행한 결과 $0.01\;[{\mu}m]$의 실리콘 채널 길이 범위까지 채널 길이에 지수적으로 감소하는 것을 보이는 비교적 정확한 결과를 얻을 수 있음을 확인하였다.

• 한국기계가공학회지
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• 제20권7호
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• pp.66-71
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• 2021

In this study, the shape design optimization of a refrigerator door hinge stopper was performed to reduce the discrepancy in the opening forces of the left and right doors of a double-door refrigerator. A finite element model was constructed and analyzed by quasi-static analyses to evaluate the structural performance of the door hinge stopper. The reaction moment calculated at the hinge axis was used as a measure of the door opening and closing forces. The design objective is to increase the door opening force by 50% while maintaining the door closing force and the maximum stress calculated in the body of the hinge stopper at the current level. A new design concept with a contacting slot was proposed to decouple the door closing and opening forces. Shape optimization was performed to determine the dimensions of the new design of the hinge stopper, and the rib pattern was determined by topological optimization to further increase the door opening force. It was observed that the new design met all design requirements.

• Structural Engineering and Mechanics
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• 제82권3호
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• pp.401-416
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• 2022

The aim of this study is to examine the frictionless double receding contact problem for two functionally graded (FG) layers pressed with a uniformly distributed load and resting on a homogeneous half plane (HP) using analytical and numerical methods. The FG layers are made of a non-homogeneous material with an isotropic stress-strain law with exponentially varying properties. It is assumed that the contact at the FG layers and FG layer-HP interface is frictionless. The body force of the FG layers and homogeneous HP are ignored in the study. Firstly, an analytical solution for the contact problem has been realized using the theory of elasticity and the Fourier integral transform techniques. Then, the problem modeled and two-dimensional analysis was carried out by using the ANSYS package program based on FEM. Numerical results for contact lengths and contact pressures between FG layers and FG layer-HP were provided for various dimensionless quantities including material inhomogeneity, distributed load width, the shear module ratio, and the heights of the FG layers for both methods. The results obtained using FEM were compared with the results found using the analytical formulation. It was found that the results obtained from analytical formulation were in perfect agreement with the FEM study.

• 한국운동역학회지
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• 제21권5호
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• pp.573-584
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• 2011

The purpose of this study was to perform a kinematic analysis of the high jump techniques of the three men's medalists at the 2011 IAAF Championships in Daegu (August 27-September 4, 2011). In particular, a three-dimensional coordinates method was used to analyze the last three strides before touchdown, the touchdown techniques, and the movements after takeoff toward the bar. An analysis of the, data for the biomechanical characteristics of the world's best high jumpers could contribute to an improvement in the performance of a national high jumper. The first conclusion of the data analysis was that the arm movements of the gold medalist, J. Williams, had a single arm form, whereas the arm movements of the other medalists were a double arm form. Second, the difference in the knee joint angles upon touchdown and toe-off was $10^{\circ}$. Third, J. Williams achieved his maximum CM height after takeoff (1.26 m) using the maximum flexion of his knee joint. Fourth, the foot contact duration of A. Dmitrik (0.11 s) was the shortest among the medalists, and the ratio for his transformation of horizontal velocity to vertical velocity was the greatest (75.25%) among the three. Last, the maximum CM height of T. Barry was the greatest, and his foot contact duration was the longest.

• 한국어류학회지
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• 제33권2호
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• pp.45-56
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• 2021

납자루 Tanakia lanceolata와 한강납줄개 Rhodeus pseudosericeus 간의 속간잡종으로 추정되는 수컷 1개체를 서해안 독립 하천인 보령 대천천에서 채집하였다. 해당 속간잡종 개체의 명확한 기원을 판별하기 위하여 형태학적 및 분자계통학적 분석을 수행하였다. 형태학적 분석 결과, 속간잡종 개체의 등지느러미 앞쪽 상단과 뒷지느러미 가장자리의 색상, 등과 배 쪽 색상 등은 납자루의 형태적 특징을 따랐으며, 미병부 중앙에 파란색 체측종대가 존재하는 점, 측선이 불완전한 점, 입수염이 없는 점 등은 한강납줄개의 형태적 특징을 따랐다. 또한, 미토콘드리아 DNA의 cytb 유전자 분석 결과, 속간잡종 개체는 납자루와 99.82~100%의 염기서열 유사도를 나타내어, 모계 종은 납자루로 판단되었다. 핵 DNA의 rag1 유전자 분석 결과, 속간잡종 개체는 납자루와 한강납줄개 간의 단일염기다형성 부위(38 bp)를 모두 반영하는 double peaks 양상을 나타내어, 부계 종은 한강납 줄개로 판단되었다. 따라서 본 연구에서 분석한 납자루아과 자연 잡종 추정 개체는 암컷 납자루와 수컷 한강납줄개 간의 속간잡종으로 판명되었다.

• The Plant Pathology Journal
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• 제22권1호
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• pp.68-74
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• 2006

A new virus with a dsRNA genome was isolated and characterized from the Suhan-:neutari strain (ASI 2504) of Pleurotus ostreatus, which was characterized as long and slightly bent with small caps on the stipe of fruit body. Thirty nm isometric viruses with three dsRNA segments (approximately 2.0, 1.84 and 1.82 kb in sizes) were isolated by ultracentrifugation in sucrose gradients. Western analysis of protein extracted purified viruses with anti-virus polyclonal antibody confirmed that viruses have two specific proteins (36 and 68 kDa). Computer analysis of 2.0 kb segment shows that high. sequence identity with RNA-dependent RNA polymerase (RdRp) of partitiviruses, respectively. When compared to other dsRNA mycoviruses in a phylogenetic analysis, OMDV was most related to Pleurotus ostreatus virus 1.