• 대한설비공학회:학술대회논문집
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• 대한설비공학회 2006년도 하계학술발표대회 논문집
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• pp.743-748
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• 2006

Ren et al. analyzed the performance of the indirect evaporative cooler according to the direction of the flow considering evaporation water flow and wetness. However the effect of NTU of each channel on the performance of the indirect evaporative cooler according to the direction of the flow was not analyzed exactly. In this study the effect of the direction of the flow on the Indirect evaporative cooling performance changing NTU of each channel are investigated theoretically. The cooling process of the indirect evaporative cooler by flow direction is modeled into a set of linear differential equations and solved to obtain the exact solutions to the temperatures of the hot fluid, the moist air, and evaporation water. Based on the exact solution in the case of different NTU of each channel, we study the change of the distribution of the temperature according to each flow direction and at the same time analyze the effect of the flow direction on the cooling performance.

• 대한물리의학회지
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• 제16권2호
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• pp.1-8
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• 2021

PURPOSE: This study examined the effects of changes in the head direction (forward, upward 10° and downward 10°) on the quadriceps, center of pressure (COP), and foot pressure during squat exercises. The aim was to determine if the head direction could better activate the quadriceps muscle and provide a safer and stable squat posture during squat exercise. METHODS: Fifteen healthy college students were asked to stand on a Zebris, and three electrodes for sEMG were attached to their vastus medialis oblique (VMO), vastus lateralis (VL), and rectus femoris (RF) muscles. The participants then performed squatting exercises under three head directions (forward, upward 10°, and downward 10°). Surface electrodes were then used to record the EMG data during exercise. The Zebris FDM-SX was used to measure the foot pressure and COP of the participants. RESULTS: In squat exercise, the upward head direction group showed significantly higher VL activation than the downward head direction group (p < .05). The upward head direction group showed a significant backward change in the deviation of the COP than the downward and forward groups (p < .05). The upward head direction group showed a significant decrease in forefoot pressure than the downward and forward groups (p < .05) and an increase in the hindfoot pressure compared to the downward and forward groups (p < .05). CONCLUSION: The head direction upward in squat exercise has a positive effect on the quadriceps.

• Journal of the Korean Wood Science and Technology
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• 제31권3호
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• pp.61-69
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• 2003

This study investigated the effect of moisture content and loading direction on dowel bearing strength of two types of SCL. Dowel bearing tests of LVL and PSL were conducted with two different MC level, 7.5% and 19%, and two different oriention, L-direction(loading parallel to grain) and X-direction(loading perpendicular to grain). Most of specimens showed typical load-deformation curves and intersected 5% offset line. Failure modes were classified into two categories; spliting(for L-direction specimens) and peeling(for X-direction specimens). Dowel bearing strength generally decreased with increasing MC. The decreasing rate was more significant in X-directon. ESG also decreased with increasing MC, and the ratio of ESG of 7.5% versus 19% was about 1.47. Dowel bearing strength of LVL and PSL in L-direction was higher than that of X-direction. This results indicated that MC and loading orientation had a significant effect on dowel bearing strength of SCL. The average dowel bearing strength of LVL were higher than that of PSL in each loading direction. Two types of probability distribution model were chosen to quantify strength distribution, normal and 2-parameter weibull distribution. The two models showed good agreement with the data, especially in lower tail of the cumulative distribution. Normal and 2-parameter weibull distribution seemed to proper model of the dowel bearing strength for each MC levels.

• 한국분무공학회지
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• 제28권4호
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• pp.198-206
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• 2023

In this study, visualization of in-cylinder spray behavior and spark channel stretching by air flow characteristics depending on engine operating conditions were investigated. For in-cylinder spray behavior, increase in engine rpm did not alter the counter-clockwise air flow direction and location of in-cylinder dominant air flow but increased average air flow velocity, which hindered spray propagation parallel to the piston surface. When injection timing was retarded, direction of in-cylinder dominant air flow was changed, and average air flow velocity was reduced resulting in an increase in spray penetration length and change in direction. For spark channel stretching, increase in air flow speed did not affect spark channel stretch direction but affected length due to increase in spark channel resistance and limitation of energy ignition coil can handle. Change in air flow direction affected spark channel stretch direction where the air flow was obstructed by ground electrode which caused spark channel direction to occur in the opposing direction of air flow. It also affected spark channel stretch length due to change in air flow speed around the spark plug electrode from the interaction between the air flow and ground electrode.

• 한국인터넷방송통신학회논문지
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• 제17권6호
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• pp.217-222
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• 2017

지구 중력장 내에 위치한 물체는 연직 아래 방향의 힘을 받고 있다. 중력장 내에서 물체의 운동을 기술하기 위하여 운동상태 방정식을 이용한다. 자유 낙하하는 물체를 해석할 때 기준 방향은 연직 하방을 +y으로, 연직위로 던져 올린 물체를 해석할 때 기준방향은 연직상방을 +y으로, 연직 아래로 던져 내린 물체를 해석할 때, 기준 방향은 연직 하방을 +y으로 선택하여 해석함이 일반적이다. 이 논문에서는 두 벡터의 스칼라 곱 (즉, 도트 곱)을 이용하여 연직 상방 또는 하방 두 경우를 방향으로 선택하여 구성한 벡터 운동 상태 방정식(vector kinematics equations)을 해석의 결과가 서로 일치함을 제시한다. 두 벡터의 스칼라 곱 (즉, 도트 곱)을 이용하여 물체의 상태 방정식를 해석한 예는 선행 연구에서 거의 찾아볼 수가 없다. 이 결과를 이용하면, 수평면의 방향 또는 빗각을 이루는 방향의 초속도로 던져 올리거나 던져 내린 물체의 운동 상태를 해석하기 위하여 연직 기준 방향을 상방 또는 하방으로 임의 선택할 수가 있다.

• 한국인터넷방송통신학회논문지
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• 제18권5호
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• pp.89-95
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• 2018

본 논문에서는 항공기에서 사용되는 방향 탐지용 안테나가 항공기에 장착 될 경우, 항공기 구조, 회절과 반사에 의한 안테나 성능 변화를 분석하였다. 방향 탐지용 안테나는 항공기 전자전 체계(Electronic Warfare System)의 방향 탐지(DF : Direction Finding) 장치에서 레이더 위협 신호를 수신하는 안테나이다. 최근 항공기에 다양한 안테나가 장착되므로 탑재된 안테나 성능 해석 및 안테나 간섭 분석 등의 다양한 해석이 요구되고 있다. 본문에서는 모사된 항공기에 50% 대역폭을 가지는 광대역 방향 탐지용 안테나를 장착하여 전자파 해석을 진행하였고, 안테나의 단일 성능과 항공기에 탑재된 성능을 비교하여 방향 탐지 성능을 분석하였다. 분석된 방향 탐지 정확도는 $6.47^{\circ}$ RMS를 가지며 항공기 방향 탐지용 안테나로 적합함을 예측하였다.

• 건축역사연구
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• 제18권2호
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• pp.65-83
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• 2009

This research was to analyze the direction ideas of residential Feng Shui. In ancient China residential places were been established by Xiangzhai(相宅) and Buzhai(卜宅) usages. And ancient Chinese always considered geographical features of mountains and waters for setting up their living places. Geographical features were also considered importantly ih representative residential Feng Shui books, Zhaijing(宅經) and Yangzhaisanyao(陽宅三要). In Zhaihing, 24 direction ideas are co-related with Fagui(八卦) and GanZhi(千支) theories, and they are most important residential Feng Shiui direction theories. The basic thoughts of 24 direction ideas of Zhaijing were already formed in Qin(秦) dynasty and modified in early Han(漢) dynasty. In Zhaijing, residential places were splited into Yangzhai(陽宅) and Yinzhai(陰宅) according to YinYang's Qi directions. Those were actually formed from meticulous observations on changing processes of YinYangWuXing(陰陽五行)'s Qi(氣). Constantly changed Qi of YinYangWuXing were studied by old chinese people from the observations on the sun, the moon, the five stars, the Great Bear, and ErShiBaXiu(二十八宿). The origin of Zhaijing's direction ideas is the direction system of ShiPan(式盤) in Qin and Han dynasty. On ShiPan TianGan(天干) Dizi(地支) Fagui TianDiRenGui(天地人鬼) were arranged very systematically into four and 24 directions. DongxiSizhai(東西四宅) theories of Yangzhaisanyao had edited more lately than Zhaijing(宅經), and formed according to Fagui(八卦)'s YinYang(陰陽) principles. But the basic ideas is same with Zhaihing's. It proves that residential Feng Shui theories were constantly improved and modified. And both residential Feng Shui direction ideas of Zhaijing and Yangzhaisanyao are the gentral ideas in old china. The point of that ideas is Sky's four or 24 directions are correspndence with the earth's. It came from the traditional thoughts that Heaven, Earth, and mankind are c0-related and influenced each other according to Qi's changing processes. Gather up above mentioned, the direction ideas of residential Feng Shui is a systematic thoughts of old chinese for harmonizing Tian-Di-Ren-Gui, and is their specific methods for harmonizing the nature's Qi, mankind and spirits.

• Journal of Welding and Joining
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• 제23권6호
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• pp.37-42
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• 2005

Most of the welding steel plate structures have complicated mechanical problems such as rolling directional characteristics and residual stresses caused by manufacturing process. For the enhancement of reliability and safety in those structures, therefore, a systematic investigation is required. SS400 steel plate used for common structures was selected and welded by FCAW butt-welding process for this study, and then it was studied experimently about characteristics of fatigue crack propagations with respect to rolling direction and welding residual stress of welded steel plates. When the angles between rolling direction and tensile loading direction in base material are increased, their ultimate strength not show a significant difference, but yielding strength are increased and elongations are decreased uniformly. It is also shown that fatigue crack growth rate can be increased from those results. When the angles between welding bead direction and loading direction in welded material are increase, fatigue crack growth rate of them are decreased and influenced uniformly according to the conditions of residual stress distribution. In these results, it is shown that the welded steel plate structures are needed to harmonize distributed welding residual stress, rolling direction and loading direction fur the improvement of safety and endurance in manufacture of their structures.

• 전자공학회논문지 IE
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• 제43권4호
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• pp.76-82
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• 2006

자동차 바퀴 방향 지시기란 운전자가 차 내부에서 자동차의 바퀴 방향을 실시간으로 알 수 있도록 전자 장비에 바퀴의 방향을 표시해주는 시스템으로서, 본 연구에서는 자동차 핸들의 회전량을 측정하여 LED(Light Emitted Diode)와 LCD(Liquid Crystal Display)에 자동차 바퀴에 대한 방향 정보를 표시하는 시스템을 개발하고자 한다. 즉, 이렇게 자동차의 핸들 회전량을 측정하여 그 측정 데이터를 데이터 처리부에 적절하게 적용함으로써 자동차 내부에서 운전자가 인지할 수 있도록 해준다면 주차된 차를 주행하기 위해 자동차 창문을 열고 바퀴 방향을 봐야하는 등의 번거로움을 해소시킬 수 있을 것이라 사료된다.

• Journal of Magnetics
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• 제21권3호
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• pp.421-424
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• 2016

The purpose of this study is to evaluate an effectiveness of switching turbo direction to improve motion artifacts of small bowels and aorta. From June to October 2015, 60 patients suspected of having Crohn's disease were enrolled. The MR Enterography scans were performed using same protocol other than the turbo direction: with the Z phase encoding (group A) and with Y phase encoding (group B). Qualitative analysis of each group was performed to evaluate the effectiveness of switching turbo direction from Z to Y. As a result, the 5-point Likert scale for paired observers were $2.33{\pm}0.88$ for group A and $3.80{\pm}0.85$ for group B on dynamic contrast enhanced coronal images. In conclusion, group B is proved to be superior to group A and can lessen the motion artifacts derived from phase shifts.