• 감성과학
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• 제7권4호
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• pp.19-24
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• 2004

본 연구의 목적은 관절계 댐핑특성을 상용 에르고미터(BIODEX)의 등속운동을 이용하여 파악할 수 있는지를 평가하는 것이다. 제안된 방법은 등속운동을 유지하기 위해 인가한 외부토크와 하퇴의 관성토크의 차로부터 슬관절의 댐핑토크를 계산하는 것이다. 댐핑토크는 여러 가지 관절각속도에서 산출되었고, 이로부터 댐핑특성을 유도하였다. 실험장치는 BIODEX 시스템과 별도의 힘센서 및 Labview 시스템으로 구성되었다. 댐핑특성의 해석에는 Matlab을 사용하였다. 실험결과로부터 등속운동의 기동 및 종료를 위한 크랭크 암의 가속 및 감속으로 인한 미세한 각속도의 변화가 댐핑토크의 영향보다 큰 관성토크를 유발하는 것을 알 수 있었다. 따라서, 현재의 등속운동장비로는 댐핑특성을 추정하기가 어렵다고 보여진다.

• 한국환경과학회지
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• 제1권2호
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• pp.125-136
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• 1992

Digestion of a municipal wastewater sludge by the anaerobic sequencing batch reactor (ASBR) was investigated to evaluate the performance of the ASBR process at a critical condition of high-solids-content fined. The reactors were operated at an HRT of 10 days with an equivalent loading rate of 0.8-1.5 gVS/L/d at 35$^{\circ}C$ The main conclusions drawn from this study were as follows: 1. Digestion of a municipal wastewater sludge was possible using the ASBR in spite of high concentration of settleable solids in the sludge. The ASBRS with 3- and 4-day cycle period showed almost identical high digestion performances. 2. No adverse effect on digestion stability was observed In the ASBRS in spite of withdrawal and replenishment of 30% or 40% of liquid contents. A conventional anaerobic digester could be easily converted to the ASBR without any stability problem. 3. Flotation thickening occurred in thicken step of the ASBRS throughout steady state, and floating bed volume at the end of thicken period occupied about 70% of the working volume of the reactor Efficiency of flotation thickening in the ASBRS could be comparable to that of additional gravity thickening of a completely mixed digester. 4. Solids were accumulated rapidly in the ASBR during start-up period. Solids concentrations in the ASBRS were 2.6 times higher than that in the completely mixed control reactor at steady state. Dehydrogenase activity had a strong correlation with the solids concentration. Dehydrogenase activity of the digested flu형e in the ASBR was 2.9 times higher than that of the flu형e in the control reactor, and about 25 times higher than that of the subnatant in the ASBR. 5. Remarkable increase in equivalent gas production of 52% was observed at the ASBRS compared with the control reactor in spite of similar quality of clarified effluent from the ASBRS and control reactor. The increase in gas production from the ASBRS was believed to be combined results of accumulation of microorganisms, higher driving force applied, and additional long-term degradation of organics continuously accumulated.

• International Journal of Automotive Technology
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• 제8권6호
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• pp.731-744
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• 2007

A method for dynamic analysis and design calculation of a Powertrain Mounting System(PMS) including Hydraulic Engine Mounts(HEM) is developed with the aim of controlling powertrain motion and reducing low-frequency vibration in pitch and bounce modes. Here the pitch mode of the powertrain is defined as the mode rotating around the crankshaft of an engine for a transversely mounted powertrain. The powertrain is modeled as a rigid body connected to rigid ground by rubber mounts and/or HEMs. A mount is simplified as a three-dimensional spring with damping elements in its Local Coordinate System(LCS). The relation between force and displacement of each mount in its LCS is usually nonlinear and is simplified as piecewise linear in five ranges in this paper. An equation for estimating displacements of the powertrain center of gravity(C.G.) under static or quasi-static load is developed using Newton's second law, and an iterative algorithm is presented to calculate the displacements. Also an equation for analyzing the dynamic response of the powertrain under ground and engine shake excitations is derived using Newton's second law. Formulae for calculating reaction forces and displacements at each mount are presented. A generic PMS with four rubber mounts or two rubber mounts and two HEMs are used to validate the dynamic analysis and design calculation methods. Calculated displacements of the powertrain C.G. under static or quasi-static loads show that a powertrain motion can meet the displacement limits by properly selecting the stiffness and coordinates of the tuning points of each mount in its LCS using the calculation methods developed in this paper. Simulation results of the dynamic responses of a powertrain C.G. and the reaction forces at mounts demonstrate that resonance peaks can be reduced effectively with HEMs designed on the basis of the proposed methods.

• 한국실내디자인학회논문집
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• 제26호
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• pp.26-34
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• 2001

The problems with the small exhibition buildings such a small gallery and art center recently constructed did not make the characteristics of the place specifying and did not form a big flow in the line of urban connection. Also it was deficient in the image like a cultural space because of the commercial aspects of the individual buildings. According to this view, this study is to evaluate the exteriors of the small exhibition buildings that the public prefers on the psychological side as a design theory and then, it is to present the direction of desirable form constitution hereafter. In the design of the small exhibition buildings exterior that the public must prefers, the principles and techniques of constitution that operate are the most initiative as follows. As for the principles of unity in the constitution of the small exhibition buildings exterior that the public prefers, Eigen Value is 7.573 and the explanatory force takes 21.637% at the top and it plays a leading role. In the comparison of the appearance, it shows that it is a factor with the largest specific gravity. The next factors were grouped in good order: the balance, ornamental technique, change, shipping technique, rhythm, harmony, symbolic technique, area technique and adding technique. As a result, in the design of the small exhibition buildings exterior, the architects have to constitute the principles of balance, change, rhythm and harmony by most of the unity and the symbolic technique and form technique by most of the ornamental techniques harmoniously and have to give Identity like exhibition buildings.

• 한국방재학회 논문집
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• 제4권2호
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• pp.47-52
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• 2004

조적조 건축물은 작은 인장력과 연성능력으로 인해 지진발생시 심각한 피해상황을 나타내고 있다. 국외의 경우 조적조 건축물에 대한 여러 가지 보강방법이 사용되고 있으나, 국내의 경우 여러 가지 제약에 의하여 유리섬유보강방법을 사용하는 것이 적절하다. 본 논문에서는 유리섬유보강을 통한 지진피해를 입은 조적조 건축물의 내진성능에 관해 평가하였다. 실험결과 유리섬유보강 실험체의 최대 밑면 전단력과 변형이 현저하게 증가하였다. 파괴이후에도 유리섬유보강 실험체는 계속 하중에 저항하는 것으로 나타났다. 유리섬유보강 실험체는 전반적으로 pier 부분에서 Rocking 거동을 보였다.

• 한국산학기술학회논문지
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• 제14권10호
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• pp.5176-5183
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• 2013

일반적으로 국내에서의 경량기포콘크리트는 건축용 온도구조용 단열재나 토목용 폐공 채움재, 터널의 뒤채움재 등으로 사용되고 있으며 기타 사무실 바닥 충전재, 경량블록제조 등으로 사용되어지고 있다. 이러한 경량기포콘크리트의 사용범위를 확대하여 연약지반에 도로건설시 등간격으로 말뚝을 설치하여 기층으로 사용하는 공법을 연구중에 있다. 본 연구에서는 경량포장체의 연약지반에서의 거동 특성을 분석하기위해 지오센트리퓨지 시험을 이용하였다. 실제 포장체를 1/30로 축소한 슬래브 형태의 모형을 카올리나이트로 조성된 연약지반에서 시험을 실시하였다. 말뚝 배열은 무리말뚝(36본 $3{\times}12$)로 제작하여 사용하였다. 시험 중력 레벨은 실중력의 30배로 원심력을 작용하여 실험하였으며 이때 작용하는 경량포장체 모형의 거동특성을 바탕으로 실제 경량포장체의 거동특성을 추정하였다. FMA해석결과의 10배인 39.4kg(실제 하중35ton)의 횡하중를 가했을 경우 7.8mm(실제 거동 23.4mm)의 미세한 거동만 있었다.

• 한국운동역학회지
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• 제16권3호
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• pp.43-51
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• 2006

The purpose of this study was to analyze kinematic variables during turing back kick motion of Taekwondo. The subjects of this study were the 4 skilled and 4 unskilled of male university player in respectively. The experiment of this study was used two 16mm high speed cameras and its speed 125 frames/s. Analysis of this data was three dimensional cinematography using KWON3D program package. The results were as following; 1. In the elapsed time, there was no significance difference statically between a skilled and unskilled group. But skilled group was more fast during the motion of I phase. And unskilled group was more fast during the motion of II phase so called force production section, which had an influence on Diechagi's velocity. 2. In the center of gravity of human body, the changing of it was $1.10{\pm}0.04m$, $1.12{\pm}0.03m$ of LFM(left foot movement) and $1.36{\pm}0.08m$, $1.39{\pm}0.09m$ of RKF(right knee flection), and $1.44{\pm}0.08m$, $1.42{\pm}0.09m$ of RFI(right foot impact). There was no significance difference statically between the two groups. 3. The velocity of heel on impact was 1.13m/s in the skilled group and 1.23m/s in the unskilled group, when each angle of knee was $110.4{\pm}10.9deg/s$, $114.8{\pm}28.4deg/s$. The maximum velocity of each performance was reached before the RKF, and the velocity and angle at impact along by two groups did not show any significant difference statically. 4. In the angular velocity of just RKF of lower leg, there was significance difference statically between the two groups(p<.05).

• 대한토목학회논문집
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• 제14권5호
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• pp.1145-1158
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• 1994

물의 유동(流動)에 관한 계산상 효율성(效率性)을 갖는 자유수면(自由水面)을 고려한 3차원(次元) 유한차분(有限差分) 수직모형(數値模型)을 개발하였다. 수직모형(數値模型)은 연직방향(鉛直方向)에 대해 정규화(正規化)한 좌표(座標)(${\sigma}$-coordinate)를 사용하며, 시간(時間) 적분방법(積分方法)으로는 반음해법(半陰解法)(semi-implicit)을 사용하여 계산시간(計算時間)의 효율성(效率性)을 도모하였다. 모드분리(mode-splitting)개념을 도입하여 내부모드(internal mode)에 대해서는 양해법(陽解法)을 사용하였으며, 외부모드(external mode)는 수평방향(水平方向) 운동량방정식(運動量方程式)들과 연속방정식(連續方程式)의 차분식(差分式)으로부터 구한 타원형(楕圓型) 차분방정식(差分方程式)을 SOR방법에 의하여 해석하였다. 이와 같은 방법은 계산(計算) 시간간격(詩間間隔)이 표면(表面) 중력파(重力波)에 대한 CFL(Courant-Fredrich-Lewy)조건에 의해 제약을 받지 않아 계산시간(計算時間)의 효율성을 도모할 수 있다. 개발된 모형은 1차원(次元) 수로(水路)에서 취송유(吹送流)의 연직분포(鉛直分布)에 대한 해석해(解析解)와 비교(比較) 및 연직(鉛直) 가변격자(可變格子)의 도입에 따른 오차분석(誤差分析) 정사각형(正四角形) 호수(湖水)에서 취송유(吹送流) 계산(計算) 및 차분화(差分化) 상수(常數)들의 민감도(敏感度) 분석(分析)을 수행하였다.

• 대한기계학회논문집B
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• 제36권5호
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• pp.477-485
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• 2012

수평 덕트 내 임계점부근의 유체 유동 및 열전달특성은 중력과 함께 임계영역에서의 열역학 및 전달 물성치의 많은 변화와 직접적으로 연관되어 있다. 본 연구에서는 수평 직사각 덕트 내 임계점부근의 물에 대한 대류열전달특성을 전산해석을 통하여 분석하였다. 이를 통해 국부적인 열전달계수와 유속, 온도, 그리고 물성치분포를 포함한 대류열전달특성에 대해 임계점 근접효과와 함께 비교하였다. 벽으로부터의 열전달에 따른 유체 밀도감소로 덕트 내 유동방향으로의 유속증가와 함께 유체가 액체에서 기체 같은 상태로 천이하는 형태의 유동장특성을 보여준다. 덕트의 윗면, 옆면, 그리고 아래면 각각의 국부적인 열전달계수분포에 큰 차이가 있으며 준임계점 온도부근에서 난류전달특성의 향상으로 열전달계수의 최대치에 이르게 된다. Nu 수는 덕트 내 압력과 종횡비에 영향을 받으며 임계압에 가까워질수록 최대 Nu 수는 급격히 증가하게 된다. 이와 함께 기존의 열전달상관식을 통한 결과와 예측된 Nu 수 분포를 비교하였다.

• Asian-Australasian Journal of Animal Sciences
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• 제16권12호
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• pp.1804-1808
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• 2003

A layer experiment was conducted to determine the effects of supplementary methionine chelates (Cu, Zn and Mn), individual or in combination, on laying performance, eggshell quality, gizzard erosion, and IgG level of serum for 8 weeks. Five hundred 96-wk-old force molted ISA Brown layers were assigned to five dietary treatments. Basal diet was formulated to meet or exceed the nutrients requirements listed in NRC (1994). Five experimental diets were control, Zn-methionine chelate (Zn-Met) supplemented, Cumethionine chelate (Cu-Met) supplemented, Zn-Mn-methionine chelate (Zn-Mn-Met) supplemented and Zn-Mn-Cu-Met supplemented diet. Each treated diet was supplemented with respective mineral(s) at the level of 100 ppm in the form of methionine chelate. Egg production was increased by Cu-Met supplementation but decreased by Zn-Met supplementation. Egg weight was significantly (p<0.05) lower in Cu-Met treatment than those of the control and Zn-Met treatment. Specific gravity of eggs and eggshell strength were highest and soft egg production was lowest in Cu-Met treatment. Gizzard erosion index was significantly increased by supplementation of Cu-Met, Zn-Mn-Met or Zn-Mn-Cu-Met. Zinc content in liver significantly increased by Zn-Met, but not by Zn-Mn-Cu-Met treatment. In conclusion, 100 ppm Cu in Cu-Met chelate improved laying performance and eggshell quality but also increased gizzard erosion index. Supplementation of Zn-Met or its combination with other mineral chelates had no beneficial effects on laying performance and eggshell quality.