• Transactions of the Korean Society of Mechanical Engineers
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• v.17 no.10
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• pp.2475-2482
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• 1993

The effects of the hole size(2R) and the specimen width(W) on the fatigue strength and the fatigue life in plain woven glass/epoxy composite plates are experimentally investigated under constant amplitude tensile fatigue loading. It is shown in this study that the notch sensitivity under fatigue loading is lower than that under static loading. It can be explained by the fact that the stress concentration is relaxed by the damage developed at the boundary of circular hole. To predict the fatigue strength at a specific cycle, the modified point stress criterion represented as a function of the geometry of the specimen(2R and W) is applied. It is found that the model used in the prediction of the notched tensile strength predicts the fatigue strength with reasonable accuracy. A model for predicting the fatigue life in the notched specimen, based on the S-$N_f$, curve in the smooth specimen, is suggested.

• Journal of the Korean Chemical Society
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• v.54 no.5
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• pp.603-610
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• 2010

The potential feasibility of Maghnia clay as adsorbent to remove three cationic dyes (methylene blue (MB), neutral red (NR) and malachite green oxalates (MG)) from aqueous solution was investigated at various operating parameters such as contact time, pH, initial dye concentration and adsorbent dose. Optimum pH values for dyes adsorption were 6 for NR and 7 for MB and MG, respectively. Maximum adsorption of dyes, i.e. $\geq$ 90% has been achieved in aqueous solutions in 60 minutes. The adsorption of dyes followed the pseudo-second-order rate equation.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.20 no.4
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• pp.1241-1250
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• 1996

The characteristics of fatigue cumulative damage and fatigue life of 8-harness satin woven CFRP composites with a circular hole under constant amplitude and 2-level block loading are estimated by Stochastic Makov chain model. It is found in this study that the fatigue damage accumulation behavior is very random and the fatigue damage is accumulated as two regions under constant amplitude fatigue loading. In constant amplitude fatigue loading the predicted mean number of cycles to a specified damage state by Markov chain model shows a good agreement with the test result. The predicted distribution of the fatigue cumulative damage by Markov chain model is similar to the test result. The fatigue life predictions under 2-level block loading by Markov chain model revised are good fitted to the test result more than by 2-parameter Weibull distribution function using percent failure rule.

• Korean Journal of Child Studies
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• v.36 no.4
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• pp.33-48
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• 2015

It is generally known that children's development of 'gender schema' and 'gender role stereotype' has a positive relationship with the notion of 'gender role preference'. This study analyzed an unusual case focusing on the role playing of two brothers'. The elder brother, Hyoung-Gyoo, always preferred to take the female role, and he had a preference for feminine names like "Cordelia" whilst engaging in role playing situations. The brothers can be said to have crossed the border into the realm of intersexual role playing. The results revealed Hyoung-Gyoo's clear discrepancy between gender-related perceptions and reality, and showed his younger sibling Je-Gyoo's high level of acceptance towards his brother's extraordinary gender role preference. The results of this study can serve as a useful reference point for detailing unusual development from early childhood regarding 'opposite-gender-role seeking' characteristics.

• Journal of Wetlands Research
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• v.11 no.2
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• pp.89-98
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• 2009

This study determines the stream mean slope, stream slope and longitudinal stream profile based on the concept of informational entropy. Maximizing the entropy will make the probability distribution of longitudinal stream profile as uniform as possible while satisfying the constraints. Using this relationships the mean stream slope, stream slope and longitudinal stream profile formulas were derived. The parameters of the applied streams were estimated by the least square method using the geomorphological factors of Dalchon stream basin obtained from Chungcheong Buk-Do local stream consolidation scheme drawings. The comparative investigation was performed between the observed and simulated mean stream slope and longitudinal stream profile, and are in good agreement with the measured data. It is noted that this results can be used in the estimation of stream mean slope and longitudinal stream profile.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2013.06a
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• pp.198-200
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• 2013

최근 국제해사기구(IMO)의 해양환경보호위원회에서(MEPC)는 선박에서 대기로 방출되는 CO2의 양을 최소로 하기 위해서 신조선 설계 건조시 에너지효율지수(EEDI : Energy Efficiency Design Index for new ships), 에너지 효율지표(EEOI : Energy Efficiency Operational Indicator), 그리고 에너지 효율관리 계획(SEEMP : Ship Energy Efficiency Management Plan) 지수들을 이용하여 전 세계 이산화탄소 배출 규제 방침을 운영하고 있다. 이러한 환경규제 강화와 발맞추어 세계 각국은 지속적인 Green-ship의 개발과 저탄소 고효율 선박의 운항을 위해 연구와 노력한다. 본 연구에서는 선박이 움직이는데 있어 동력이 시작되는 부분과 그 힘이 전달되어 운항자의 의식이 반영되어 선체의 이동으로 이어지기까지 흐름에 대해 도식 및 수식으로 정리하였다. 그리하여 해상의 상태와 이에 따른 운항결정이 어떤 결과를 초래할 수 있는지 살펴보고 이 부분에서 운항효율을 증대시킬 수 있는 부분에 대해 모색해 보았다. 또한 엔진의 상태에 따른 연료 절감율에 대해 살펴보고 보다 경제적 운항을 위한 적정 RPM과 속도 등에 대해서 고찰해 보았다. 이 같은 정리를 통해 앞으로의 Echo-ship, Green-ship의 연구방향에 대한 초석으로 삼고자 한다.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.7 no.1
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• pp.63-69
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• 2006

New design equations for calculating the lateral-torsional buckling moment resistances of singly stepped I-section beams subjected to general loading on the top flange are suggested based on the investigations of elastic finite-element analyses. The new equations presented in this study are compared with current moment gradient modifiers presented by other researchers and specifications. The study considered almost loading cases on buildings and bridges. The proposed equations should be easily used to calculate the lateral-torsional buckling moment resistance of stepped I-beams.

• 전기의세계
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• v.18 no.5
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• pp.20-25
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• 1969

The development of the frequency convertors using semiconductors devices makes it possible to control the speed of A.C. motors easily. It is now economically feasible to provide them with power at adjustable frequency using silicon-controlled rectifier (or thyristor) inverters. In such a case, in order to operate an induction motor efficiently over a wide speed range, it must be supplied from a variable frequency source of which frequency is adjustable over the speed range of the motor. It is desired to observe the changes in characteristics as primary current, torque-speed of induction motor etc. at any optional frequency. Although the characteristics can be obtained by means of the conventional methods, they require very complicated precedures of calculations. The Current Diagram Method in this paper suggests a new approach to simpler calculations of the characteristics, using the motor constants at reference frequency. The conclusions of this study are summarized as follows: 1) The equations of stator current at adjusted frequency were derived to construct graphical chart and the current circle required for the Current Diagram Method. 2) The radius, center of the current circle and the vector locus, the basis for calculating the characteristics, at any desired frequency could be easily determined with the aid of both the derived graphical chart and current circle at reference frequency. 3) The method was shown to be applicable to the various types of 3-phase induction motors and also dealt with its application to the split-phase, condenser motors.

• Communications of Mathematical Education
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• v.3
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• pp.229-249
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• 1997

폴리아가 그의 저서 ‘How to Solve It.'에서 주창한 문제 해결의 모형은 이렇게 해석될 수 있다. 곧, 절대 다수의 수학 문제는 조건문 (p${\rightarrow}$q)의 명제 형식으로 분해된다는 것이다. 그리하여 순조롭게 발생되는 문제 해법의 전과정은 아래와 같이 마치 징검다리를 놓듯 추이율(transitivity)을 연거퍼 적용하는(이른바 연추적이라 함) 절차이다. (p: 주어진 정보) ${\rightarrow}$ ${\cdots}$ ${\rightarrow}$ ${\cdots}$ ${\rightarrow}$ (구하는 정보: q) 이것은, 일반적으로, 추이율이 성립하는 모든 관계(relation)의 연추적 확인 과정으로 확장될 수 있다. 요컨대 항진식 (p${\rightarrow}$r) ${\wedge}$ (r${\rightarrow}$q) ${\rightarrow}$ (p${\rightarrow}$q)의 보장 아래 관계의 추이율 xRz ${\wedge}$ zRy ${\rightarrow}$ xRy 로 연결되는 온갖 경로를 포괄한다. 이상과 같이 정식화되는 이 도식의 한계와 효용은 (1) 모든 문제가 조건문의 형태를 갖추고 있는 것은 아니며, (2) 조건문 형식의 문제라도 해법이 반드시 연추적으로 발생되는 법도 아니고, (3) 더구나 이것이 해법 발생의 만능 열쇠는 아닐뿐더러, (4) 발상을 촉진하는 데는 교육공학적으로 더 정교한 배려가 필요하므로, (5) 초보 단계에서 행동 수정을 위한 치유 목적으로 사용됨이 바람직하다.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.11 no.10
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• pp.1814-1820
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• 2007

As RFID/USN has appeared as one aspect of the latest trend in Convergence rapidly spreading over the society, the use and the applied service of RFID/USN are expected to be diverse. USN begins by the technological means to providing the new type of service, and provides the customers with the factors in various type of its application to satisfy their desire. This thesis suggests a forecast model of the u-Distribution with expecting the new change of the new generation of distribution by using RFID/USN, which is initiatively introduced into this area. For the suggestion of the forecast model, the way of planning of it will be discussed by examining the necessity of the model. Also, the systematic and technical parts of the new forecast model will be schematized.