• 한국운동역학회지
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• 제15권4호
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• pp.25-42
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• 2005

The study was to investigate kinematic difference between flexed and extended type of knee during Jigeo-Cha-Gi in Taekwon-Do. For this subjects participated were consisted of weights of fin (1), bantam (1) and welter class(1) of male 3 national representative level skilled in two type(flexed and extended type) of Jigeo-Cha-Gi. 3D cinematography analysis was performed for motion analysis and Kwon 3D ver. 3.1) was used for 3D coordinates & analysis variables calculation. In Temporal variable there was no significant difference statistically in all phases & total elapsed time between flexed and extended type, but flexed type was delayed more 0.016 sec than extended type. In displacement of COG there was significant difference in level of p<.05 showing longer mean 6.13 cm in case of flexed type than extended type in displacement of COG during all phase and too significant difference in level of p<.01 showing longer mean 4.4 cm in case of flexed type than extended type in displacement of COG in follow through phase. In velocity of COG there was significant difference in level of p<.001 showing higher mean 15.53cm/s in case of flexed type than extended type in velocity of COG(Y direction) during targeting phase and peak velocity(Y) was more fast 8.74 cm/s in extended type than flexed type. In velocity of leading leg in forward direction(Y) there was significant difference in level of p<.05 showing higher thigh mean value in case of flexed type than extended type but showing higher foot mean value in extended type at level of p<.001 than flexed type in velocity of COG(Y direction). In velocity of leading leg in vertical direction(Z) there was no significant difference in the second & third phase in case of vertical velocity level, but momentum transferred efficiently form proximal to distal endpoint. In front-back & right-left orientation angle of trunk there was possibility of more stable Jigeo-Cha-Gi in extended than flexed type by decreasing in right-left orientation angle of trunk. In relative angle of lower leg(hip, knee, ankle) there was significant difference in level of p<.001 showing longer mean 32.74 deg. in case of flexed type than extended type in hip joint during the second phase but maintained insufficient extended knee of mean 168 deg. in targeting phase.

• 대한기계학회논문집B
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• 제23권11호
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• pp.1434-1443
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• 1999

The turbulent fluctuations of temperature and two components of velocity have been measured with hot- and cold-wires in the Thermally Stratified Wind Tunnel(TSWT). Using the fin-tube heat exchanger type heaters and the neural network control algorithm, both stable ($dT/dz=109.4^{\circ}C$) and unstable ($dT/dz=-49.1^{\circ}C$) stratifications were realized. An ambient air jet was issued normally into the cross flow($U_{\infty}=1.0 m/s$) from a round nozzle(d = 6 mm) flushed at the bottom waII of the wind tunnel with the velocity ratio of $5.8(U_{jet}/U_{\infty})$. The characteristics of turbulent dispersion in the cross flow jet are found to change drastically depending on the thermal stratification. Especially, in the unstable condition, the vertical velocity fluctuation increases very rapidly at downstream of jet. The fluctuation velocity spectra and velocity-temperature cospectra along the jet centerline were obtained and compared. In the case of stable stratification, the heat flux cospectra changes Its sign from a certain point at the far field because of the restratification phenomenon. It is inferred that the main reason in the difference between the vertical heat fluxes is caused by the different length scales of the large eddy motions. The turbulent kinetic energy and scalar dissipation rates were estimated using partially non-isotropic and isotropic turbulent approximation. In the unstable case, the turbulent energy dissipation decreases more rapidly with the downstream distance than in the stable case.

• 설비공학논문집
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• 제22권10호
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• pp.710-718
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• 2010

A numerical study was performed to predict refrigerant charge amount in a mini-channel condenser for a R410A residential air-conditioning system. Multi-channel flat tubes with 12 mini-channels of 1.17 mm average hydraulic diameter for each tube were applied to the condenser. The condenser consisted of 3 passes, and the first, second, and third pass had 44, 19, and 11 tubes, respectively. Each pass was connected by a vertical header. In this study, the condenser was divided into 410 finite volumes, and analyzed by an $\varepsilon$-NTU method. With thermophysical properties and void fraction models for each volume element, the R410A amount distribution and a total charge amount in the condenser were calculated. The predicted total charge amount was compared with the experimentally measured charge amount under a standard ARI A condition. The developed model could predict the charge amount in the mini-channel condenser within prediction errors from -23.9% to -3.0%. Air velocity distribution at the condenser face was considered as non-uniform and uniform by the simulation model, and its results showed that the air velocity distribution could significantly influence the charge amount and vapor phase distribution in the condenser.

• 한국어류학회지
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• 제9권1호
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• pp.130-140
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• 1997

한국산(韓國産) 납자루아과(亞科)에 속하는 각시붕어(Rhodues uyekii) 골격(骨格)의 주요 형태적 특징을 기재하고자 조사를 수행하였다. 본 조사에서 R. uyekii의 두골(頭骨), 척추골(脊椎骨), 지느러미 골격(骨格)을 조사였던 바, 두개부(頭蓋部)에 fontanell이 없으며, 상사골(上篩骨)의 전단에 돌기가 없고, 유리신경간극(遊離神經間棘)이 넓은 판상(板狀)이고, 상후두골(上後頭骨)은 높은 삼각형 형태의 돌기를 갖고 있으며, 제4 안하골(眼下骨)이 매우 축소 되어 있고, 미설골(尾舌骨)의 선단(先端)이 2분지(分枝)되고 수평판(水平板)과 수직판(垂直板)의 후방(後方)이 넓어지며 후연(後緣)이 돌출되는점, 견대부(肩帶部)에는 오훼골(烏喙骨) 구멍이 존재하지 않았고, 미기추전추체에 미신경골(尾神經骨)이 나타나지 않는 특징을 보였다.

• 한국어류학회지
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• 제20권1호
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• pp.66-69
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• 2008

농어목 양쥐돔과(Acanthuridae)에 속하는 Naso hexacanthus 1개체(표준체장 351.1 mm)가 제주 북부연안에서 정치망으로 처음 채집되었다. 이 종은 등지느러미에 갈색 수직 무늬가 있고 미병부에 있는 두개의 골질판은 연한 보라색을 띠는 것이 특징이며, 이 종의 한국명을 "남방표문쥐치"라고 하였다.

• 한국어류학회지
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• 제20권1호
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• pp.74-77
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• 2008

농어목 후악치과에 속하는 Opistognathus hongkongiensis 유어 3개체(체장 38.8~51.5 mm)가 제주도 주변해역에서 채집되었다. O. hongkongiensis는 입이 크고 체측에 흑갈색 가로띠가 있으며, 등지느러미가 노랗고 검은 반점이 없는 것이 특징이다. 본 종은 국내에서 처음으로 보고되는 종으로서, 신한국명을 "줄후악치"로 제안한다.

• Smart Structures and Systems
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• 제18권2호
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• pp.249-265
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• 2016

A bimorph piezoelectric energy harvester is developed for harvesting energy under the vortex induced vibration and it is integrated to a host structure of a trapezoidal plate without changing its passive dynamic properties. It is aimed to select trapezoidal plate as similar to a vertical fin-like structure which could be a part of an air vehicle. The designed energy harvester consists of an aluminum beam and two identical multi fiber composite (MFC) piezoelectric patches. In order to understand the dynamic characteristic of the trapezoidal plate, finite element analysis is performed and it is validated through an experimental study. The bimorph piezoelectric energy harvester is then integrated to the trapezoidal plate at the most convenient location with minimal structural displacement. The finite element model is constructed for the new combined structure in ANSYS Workbench 14.0 and the analyses performed on this particular model are then validated via experimental techniques. Finally, the energy harvesting performance of the bimorph piezoelectric energy harvester attached to the trapezoidal plate is also investigated through wind tunnel tests under the air load and the obtained results indicate that the system is a viable one for harvesting reasonable amount of energy.

• Applied Microscopy
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• 제52권
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• pp.1.1-1.8
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• 2022

As semiconductor device architecture develops, from planar field-effect transistors (FET) to FinFET and gate-all-around (GAA), there is an increased need to measure 3D structure sidewalls precisely. Here, we present a 3-Dimensional Atomic Force Microscope (3D-AFM), a powerful 3D metrology tool to measure the sidewall roughness (SWR) of vertical and undercut structures. First, we measured three different dies repeatedly to calculate reproducibility in die level. Reproducible results were derived with a relative standard deviation under 2%. Second, we measured 13 different dies, including the center and edge of the wafer, to analyze SWR distribution in wafer level and reliable results were measured. All analysis was performed using a novel algorithm, including auto fattening, sidewall detection, and SWR calculation. In addition, SWR automatic analysis software was implemented to reduce analysis time and to provide standard analysis. The results suggest that our 3D-AFM, based on the tilted Z scanner, will enable an advanced methodology for automated 3D measurement and analysis.

• 한국어류학회지
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• 제36권3호
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• pp.282-287
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• 2024

2021년 6월 경남 통영시 좌사리도의 암초 지역에서 채집된 나비고기과 유어 1개체(표준체장 28.6 mm)를 근거로 Chaetodon selene를 한국첫기록종으로 보고한다. 제주도 연안에서 수중사진만으로 소개된 바 있지만, 본 연구에서 확증표본을 근거로 그 형태적 특징을 상세하게 기술하였다. 신한국명으로 '노랑점나비고기'를 채택했으며, 등지느러미 극조가 12개이고, 몸의 후반부에 흑색 초승달 무늬와 눈을 가로지르는 흑색 세로줄무늬가 있는 것이 특징이다.

• 한국항공우주학회지
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• 제48권1호
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• pp.35-42
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• 2020

비행체용 전기식 구동장치는 일반적으로 공력비행 조종날개의 편향각 또는 추력방향을 제어하는 장치로 본 논문은 공력제어와 추력방향 제어가 모두 가능한 전기식 구동장치의 설계 및 개발을 다루고 있다. 본 논문에서는 하나의 작동기로 미익과 제트 베인을 동시에 제어할 수 있고, 비행체의 표적까지 비행동안 효율을 증가시키기 위하여 수직 발사 및 고속 선회 후 제트 베인을 분리할 수 있는 새로운 소형 전기식 구동장치를 제안하였다. 이를 위하여, 푸시-푸시 링크 구조를 사용한 전기식 구동장치를 설계하였고 수학적 모델을 유도하였다. 수학적 모델은 시뮬레이션 결과와 실험 결과를 비교하여 모델의 타당성을 검증하였다. 개발된 구동장치의 성능 및 신뢰성은 성능시험, 환경시험, 지상연소시험을 통하여 검증하였다. 제안된 구동장치는 성능 및 신뢰성 뿐만 아니라 단순하고 콤팩트한 구조로 인해 비행체용 전기식 구동장치로 유용할 것으로 기대된다.