• Journal of Mechanical Science and Technology
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• 제15권12호
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• pp.1741-1749
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• 2001

Recent studies of the structure of wall turbulence have lead to the development of a conceptual model that validates and integrates many elements of previous models into a relatively simple picture based on self-assembling packets of hairpin vortex eddies. By continual spawning new hairpins the packets grow longer in the streamwise direction, and by mutual induction between adjacent hairpins the hairpins are strained so that they grow taller and wider as they age. The result is a characteristic growth angle in the streamwise-wall normal plane. The spanwise growth of individual packets implies that packets must either merge or pass through each other when they come into contact. Direct numerical simulations of the growth and interaction of spanwise adjacent hairpins shows that they merge by the vortex connection mechanism originally proposed by Wark and Nagib (199). In this mechanism the quasi-streamwise legs of two hairpins annihilate each other, by virtue of having opposite vorticity, leaving a new hairpin of approximately double the width of the individuals. PIV measurements in planes parallel to the wall support this picture. DNS of multiple hairpins shows how the spanwise scale doubles when the hairpins form an array.

• E2M - 전기 전자와 첨단 소재
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• 제8권2호
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• pp.229-236
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• 1995

Multimedia has created a system environment that needs a combination of diverse peripherals, faster I/O, and easier configuration. The sheer volume of data one can expect with multimedia hardware and applications storage systems of higher capacity and faster data transfer rate. Unlike the magneto-optical(MO)disk technology which uses bias magnetic field in writing, both the reading and the writing in the phase change (PC) technology are performed only by laser light. In PC optical media, an active layer is reversibly converted between amorphous state and crystalline state by changing irradiation conditions of focused laser beam. Thus, as compared with MO disk, the PC disk has such great advantages that signals can be reproduced by change of reflectance of laser beams in the same manner as the compact disc. The reflectivity of a phase-change spot can be altered in a single pass under the head only through modulation of laser power. The principles and the current status of phase-change optical recording media combined with possible applications are discussed in the present article.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2015년도 춘계 학술논문 발표대회
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• pp.192-193
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• 2015

The number of accidents is raising every year and severity is also increasing. A lot of studies are interested in the leading indicator such as safety culture or safety audit to reduce accidents. In particular, the studies on safety awareness are actively conducted. However, these studies showed that there was consciousness of scapegoatism which to pass responsibility of accident causes to others regardless of safety awareness. It means that there are probability about overestimating and making light of unsafe condition and act which have to manage and control. Eventually, the direct causes which lead to the fatal accident may be consistently arisen. Nevertheless, researches about consciousness of scapegoatism are shortage. Therefore, this study proposed the means to investigate the relationship between consciousness of scapegoatism and accidents through report from KOSHA and conducts the survey with suggested means. This paper will contribute to prevent accidents by identifying relationship between consciousness of scapegoatism and accidents.

• The Korean Journal of Physiology and Pharmacology
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• 제4권6호
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• pp.487-496
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• 2000

Insulin stimulates glucose transport in muscle and fat cells by promoting the translocation of glucose transporter (GLUT4) to the cell surface. Phosphatidylinositide 3-kinase (PI3-kinase) has been implicated in this process. However, the involvement of protein kinase B (PKB)/Akt and $PKC-{\zeta}$, those are known as the downstream target of PI3-kinase in regulation of GLUT4 translocation, is not known yet. An interesting possibility is that these protein kinases phosphorylate GLUT4 directly in this process. In the present study, $PKB-{\alpha}$ and $PKC-{\zeta}$ were added exogenously to GLUT4-containing vesicles purified from low density microsome (LDM) of the rat adipocytes by immunoadsorption and immunoprecipitation for direct phosphorylation of GLUT4. Interestingly GLUT4 was phosphorylated by $PKC-{\zeta}$ and its phosphorylation was increased in insulin stimulated state but GLUT4 was not phosphorylated by $PKB-{\alpha}.$ However, the GST-fusion proteins, GLUT4 C-terminal cytoplasmic domain (GLUT4C) and the entire major GLUT4 cytoplasmic domain corresponding to N-terminus, central loop and C-terminus in tandem (GLUT4NLC) were phosphorylated by both $PKB-{\alpha}$ and $PKC-{\zeta}.$ The immunoblots of $PKC-{\zeta}$ and $PKB-{\alpha}$ antibodies with GLUT4-containing vesicles preparation showed that $PKC-{\zeta}$ was co-localized with the vesicles but not $PKB-{\alpha}.$ From the above results, it is clear that $PKC-{\zeta}$ interacts with GLUT4-containing vesicles and it phosphorylates GLUT4 protein directly but $PKB-{\alpha}$ does not interact with GLUT4, suggesting that insulin-elicited signals that pass through PI3-kinase subsequently diverge into two independent pathways, an Akt pathway and a $PKC-{\zeta}$ pathway, and that later pathway contributes, at least in part, insulin stimulation of GLUT4 translocation in adipocytes via a direct GLUT4 phosphorylation.

• 한국지구과학회지
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• 제23권4호
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• pp.349-356
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• 2002

한반도 동해에서 Topex/Poseidon위성 고도레이더로부터 관측된 해수면과 울릉도, 포항, 속초의 조위계에서 관측된 해수면을 비교하여 두 자료의 연계성을 분석하고 위성에서 관측된 해수면자료의 객관성을 검증하였다. 1992년부터 1997년 사이에 관측된 T/P MGDR 관측자료로부터 해수면을 추출하기 위하여 대기보정 및 지구물리학적인 보정을 실시하였다. 조위계로부터 관측된 해수면과의 비교를 위해 조위관측소로부터 반경 약 55km내에 위치하는 관측값들을 평균하였다. 위성 해수면과 조위계 해수면을 비교한 결과 내해역에 위치한 포항 및 속초가 외해역에 위치한 울릉도에비해서 낮은 연관성을 보였다. 200일을 기준으로 저역통과필터를 처리했을 때 외해역에 위치한 울릉도는 상관값이 0.91로 매우 높은 유의성을 보였고, 내해역에 위치한 포항 및 속초는 각각 0.58 및 0.65로서 울릉도에 비해서 상대적으로 낮은 유의성을 보였다. 이러한 큰 차이는 M2, S2, K1 분조 등에 의한 조석변형 때문에 발생하는 현상으로 볼 수 있고, 이는 주로 T/P 자료처리에 사용된 조석모델의 오차로 볼 수 있고, 이를 저역통과필터를 적용하여 효과적으로 제거하였다. 대체로 외해역의 경우는 60, 120, 180, 200일의 필터를 순차적으로 처리함에 따라 상호 두 자료간의 유의성이 점차적으로 개선되는 것을 확인할 수 있었으나 내해역의 경우에는 거의 유의성이 개선되지 않는 것으로 확인되었다.

• 한국토양비료학회지
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• 제45권6호
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• pp.904-909
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• 2012

황철석 (Pyrite, FeS2)을 함유한 잠재특이산성토는 강하류 삼각지 토양, 간척지 등의 해성토뿐만 아니라, 영일만과 같은 융기해성토 지대, 내륙의 선상지하단 유기물이 많은 암흑색 토층이 있을 때에 존재하는 수가 있다. 또한 안산암 지역의 열수작용에 의해 생성되어 암맥을 따라 형성된 황철석이 광산개발이나 도로건설로 절취사면에서 노출되어 산화되면 매우 강한 산성을 띠는 특이산성토층을 형성하여 주변농경지에 피해를 주고 있다. 현재 잠재특이산성토양의 판정은 현장에서는 과산화수소로 반응 시 수증기발생 정도로 판단하거나 실내실험에서는 전황 (Total-S)성분의 함량으로 판단한다. 하지만 이들 방법은 시군농업기술센터 및 현장 진단 시 적용이 용이하지 않다. 산발생 능력평가 중 순산 발생능력실험 (Net Acid Generation, NAG pH)은 대상지역의 산성발생 가능성에 대한 예측을 정량적 계산으로 가능하다. 순산발생능력실험을 이용하여 전황함량과 NAG pH와의 상호관계를 통해 특이산성토양 판정을 제안하기 위해 화산기원의 잠재특이산성 토양과 사양질 토양을 일정비율로 혼합된 토양과 특이산성토양인 김해통과 해척통 토양에 대해 실험을 수행하였다. 전황의 함량이 0.75% 이상인 시료의 NAG pH가 2.5이며 0.75-0.50%의 중간 특이산성토양은 NAG pH 3.0으로 측정되었다. 그리고 전황 함량이 0.5-15% 약한 특이산성 토양은 NAG pH 3.8로 측정되었다. 따라서 순산발생량은 NAG pH를 이용하여 토양 내 황철석을 모두 산화시키고 pH를 측정하여 pH 3.8이하인 토양은 특이산성토양으로 구분하는 것이 타당할 것으로 판단되었다.

• 한국항행학회논문지
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• 제5권1호
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• pp.62-73
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• 2001

본 논문에서는 ITS의 통신 방식인 DSRC 시스템을 실제의 도로규격과 차량의 높이를 적용하여 성능을 분석하였다. DSRC는 LOS 전파특성을 가지므로 물리계층에서는 직접파와 도로면과 건물에서의 반사파를 고려한 2-Ray와 4-Ray로 채널을 모델링하여 각각의 모델별 경로손실을 구하였다. 이를 근거로 DSRC에서의 라이시안 심도를 유도하여 AWGN과 라이시안 페이딩, 임펄스성 잡음과 라이시안 페이딩 채널에서의 시스템 성능을 분석하였다. 그 결과 임펄스 지수가 A=0.2, ${\Gamma}^{\prime}=0.22$일 때 2-Ray 모델에서는 약 80[m], 4-Ray 모델에서는 약 40[m] 이후의 거리에서부터는 BER이 $10^{-6}$이하로 성능이 열화되었고 이를 개선하기 위하여 BCH 부호화 기법과 MRC 다이버시티 기법을 적용하여 시스템의 성능을 분석하였다.

• 대한기계학회논문집A
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• 제33권9호
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• pp.878-885
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• 2009

One of important factors in designing MEMS resonators for RF filters is obtaining a desired frequency response function (FRF) within a specific frequency range of interest. Because various array-type MEMS resonators have been recently introduced to improve the filter characteristics such as bandwidth, pass-band, and shape factor, the degrees of freedom (DOF) of finite elements for their FRF calculation dramatically increases and therefore raises computational difficulties. In this paper the Krylov subspace-based model order reduction using moment-matching with non-zero expansion points is represented as a numerical solution to perform the frequency response analyses of those array-type MEMS resonators in an efficient way. By matching moments at a frequency around the specific operation range of the array-type resonators, the required FRF can be efficiently calculated regardless of their operating frequency from significantly reduced systems. In addition, because of the characteristics of the moment-matching method, a minimal order of reduced system with a prearranged accuracy can be determined through an error indicator using successive reduced models, which is very useful to automate the order reduction process and FRF calculation for structural optimization iterations. We also found out that the presented method could obtain the FRF of a $6\times6$ array-type resonator within a seventieth of the computational time necessary for the direct method and in addition FRF calculation by the mode superposition method could not even be completed because of a data overflow with a half after calculation of 9,722 eigenmodes.

• 한국운동역학회지
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• 제16권4호
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• pp.125-134
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• 2006

The purpose of this study was to analyze the Biomechanical elements by looking at the differences on the motions of the right and left spikes of right-handed offense volleyball players, using 3D image analysis and force platform. For that purpose, spike motions of six male university volleyball players were recorded three times each using two 16mm high speed cameras and the speed of recording was set at 60 frames/sec. The coordinated raw data was leveled as 6Hz using low pass filtering method and the calculation of 3D coordinates was done by using a DLT (Direct Linear Transformation) method. Also KWON 3D program was used to analyze the variables. Through the experiments and research, the following results were found: That is, in case of the right spike, the required time from the toss to the impact, which affected the success rate of offense showed as longer and on the take-off, the exact timing to touch the ball was longer because the pace between right and left feet was wider, and also after the jump, the distance between the feet indicated shorter, than the left. In addition, the degree of somersault and horizontal adduction of shoulder joint was smaller and the degree of medial rotation of shoulder joint showed bigger than the left, so it indicated that it was not centered on the body, but by the arm with an axis of shoulder using a swing motion. After the impact, the speed of the ball indicated slower compared to the left spike.

• 한국운동역학회지
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• 제16권1호
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• pp.139-149
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• 2006

This study is to analyze the kinematic variables of inward $1{\frac{1}{2}}$ somersault in platform diver. For the manner, 3 people form the national diving team in the year 2000were chosen as the subjects and two S-VHS video cameras set in 60frames/sec were used for recording their motions. Coordinated raw positions data through digitizing are smoothing by butter-worth's low-pass filterin method at a cut off frequency 6.0Hz. and the direct linear transformation(DLT) method was employed to obtain 3-D position coordinates. The conclusions were as follows. However, horizontal distance which is the change of the COG, form the point of the jump to the point of Event 3 where the player is out of the board range completely, Subject B showed 105.1cm and 71.1cm of the vertical distance which are shorter horizontal distance and higher vertical distance, thus, took a great advantage of the position to prepare for the entry. Therefore, if a player takes higher position by speeding up the vertical velocity at the moment of the jumping off the board, and stays in the air longer, the player can have more time to show his skill. Because of the use of the characteristics of the inward somersault, keeping the safe distance form the board is important but in order to higher the completeness, it is ideal to keep the horizontal distance little over 100cm. Also, the angles of shoulder and elbow from Event 1 to 4, depending on swing of the arms, motions in the air, getting ready for the entry, showed some difference individual by individual, according to the velocity of the thigh and shank showed much difference while getting ready and take-off, and it's because of the individual's different bending and straightening for horizontal and vertical distance.