• International Journal of Naval Architecture and Ocean Engineering
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• 제13권1호
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• pp.236-245
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• 2021

In this study, direct numerical and large eddy simulations of transitional flows around studs were conducted to investigate the effectiveness of turbulence stimulators at very low speeds for the minimum propulsion power condition of four knots. For simplicity, the studs were assumed to be installed on a flat plate, while the wake was observed up to 0.23 m downstream behind the second stud. For applicability to a model ship, we also studied the flow characteristics behind the first and second studs installed on a curved plate, which was designed to describe the geometry of a bulbous bow. A laminar-to-turbulent transition was observed in the wake at Re_D ≥ 921 (U_∞≥0.290 m/s), and the wall shear stress at Re_D = 1162 (U_∞ = 0.366 m/s) in the second wake was similar to that of the fully developed turbulent boundary layer after a laminar-to-turbulent transition in the first wake. At Re_D = 581 (U_∞ = 0.183 m/s), no turbulence was stimulated in the wake behind the first and second studs on the flat plate, while a cluster of vortical structures was observed in the first wake over the curved plate. However, a cluster of vortical structures was revealed to be generated by the reattachment process of the separated shear layer, which was disturbed by the first stud rather than directly initiated by the first stud. It was quite different from a typical process of transition, which was observed at relatively high Re_D that the spanwise scope of the turbulent vortical structures expanded gradually as it went downstream.

• 한국해안·해양공학회논문집
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• 제22권5호
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• pp.326-332
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• 2010

해수 임펠러샤프트의 각종 하중에 의한 파단과 이를 개선하기위한 재설계는 정적, 동적 해석을 통한 원인분석과 유한요소법을 이용하여 효과적으로 수행할 수 있다. 본 논문에서는 전형적인 임펠러 샤프트의 파손에 대한 원인 분석을 수행하고 관련된 재설계기법을 제시하였다. 일차적으로 정적구조해석을 수행하였고 다음으로 구조물의 외력과의 공진문제를 포함한 동적해석을 수행하였다. 구조해석은 ANSYS코드를 사용하였으며, 결과적으로 파단원인을 찾아 분석하였다. 주된 파단원인은 과도한 굽힘모멘트의 발생과 응력집중, 구조물의 외력과의 공진에 의한 것으로 분석되었다. 해수 임펠러샤프트의 파단과 관련된 재설계기법의 이론적 배경을 정립하였으며, 재설계기법의 적용성과 정적, 동적 샤프트 재설계에 대한 유용성을 제시하였다.

• Korea-Australia Rheology Journal
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• 제21권2호
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• pp.83-89
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• 2009

Coating process plays an important role in information technology such as display, battery, chip manufacturing and so on. However, due to complexity of coating material and fast deformation of the coating flow, the process is hard to control and it is difficult to maintain the desired quality of the products. Moreover, it is hard to measure the coating process because of severe processing conditions such as high drying temperature, high deformation coating flow, and sensitivity to the processing variables etc. In this article, the coating process is to be re-illuminated from the rheological perspectives. The practical approach to analyze and quantify the coating process is discussed with respect to coating materials, coating flow and drying process. The ideas on the rheology control of coating materials, pressure and wet thickness control in patch coating process, and stress measurement during drying process will be discussed.

• 대한안전경영과학회지
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• 제13권1호
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• pp.189-193
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• 2011

The current standard cost for recycling applied under the Extended Producer Responsibility(EPR) institution, is not coping with continuously increased number of obligatory subject items as well as a variety of variable cost changing factors regarding the recycling treatment cost caused by price fluctuation such as increased material and labor cost entirely across the society; changes in recycling treatment process following the developing technologies; and changes in the required work forces and equipments followed by the trends of automated facilities. Despite such various cost fluctuation factors, the current EPR is not coping with the trends, making the re-calculation process difficult, which causes differences between the real treatment cost for recycling. In this study, the analysis was made on main factors affecting on the related cost and the related price changing index was calculated, by conducting the influence evaluation on the standard cost factors of the current standard cost for recycling. Through theses results, more objective standard will be set for the re-calculation of standard cost for recycling to greatly contribute to setting up the midterm and long-term strategies in the future towards efficient institution.

• 한국재료학회지
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• 제16권5호
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• pp.312-317
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• 2006

Binary skutterudite $CoSb_3$ compounds were prepared by the encapsulated induction melting (EIM) process, and their thermoelectric, microstructural and mechanical properties were examined. Single-phase ${\delta}-CoSb_3$ was successfully produced by the EIM and subsequent heat treatment at 773 K-873 K for 24 hours in vacuum. Seebeck coefficient increased with increasing heat treatment temperature up to 673 K, showing the positive signs in the range of measuring temperature. However, the samples heat-treated at 773 K-873 K showed negative Seebeck coefficient from room temperature to 400 K, while it showed positive signs above 400 K. Electrical resistivity decreased with increasing temperature, showing typical semiconducting conductivity. Thermal conductivity decreased drastically with increasing heat-treatment temperature. This is closely related with the phase transition to ${\delta}-CoSb_3$.

• 한국전기전자재료학회논문지
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• 제29권7호
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• pp.400-403
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• 2016

The resistive memory switching characteristics of resistive random access memory (ReRAM) using the amorphous GeSe thin film have been demonstrated at Al/Ti/GeSe/$n^+$ poly Si structure. This ReRAM indicated bipolar resistive memory switching characteristics. The generation and the recombination of chalcogen cations and anions were suitable to explain the bipolar switching operation. Space charge limited current (SCLC) model and Poole-Frenkel emission is applied to explain the formation of conductive filament in the amorphous GeSe thin film. The results showed characteristics of stable switching and excellent reliability. Through the annealing condition of $400^{\circ}C$, the possibility of low temperature process was established. Very low operation current level (set current: ~ ${\mu}A$, reset current: ~ nA) was showed the possibility of low power consumption. Particularly, $n^+$ poly Si based GeSe ReRAM could be applied directly to thin film transistor (TFT).

• 한국기계가공학회지
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• 제14권6호
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• pp.27-34
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• 2015

Dynamic vibration absorbers are widely used in machinery, buildings, and structures, including bridges. Two cases of their usage are considered in this paper. One is a simply supported beam subjected to either a moving force or a sequence of moving forces, which simulates a train-bridge interaction problem. The other is a case where a primary system is mounted on a base that is not grounded and is excited by an external force. The conditions that the dynamic vibration absorbers must meet in these cases are found and compared to those for usual cases where bases of primary systems are grounded.

• 한국국방경영분석학회지
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• 제24권2호
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• pp.17-29
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• 1998

This paper is to aimed to design a model of Korea defense information resource management structure from the viewpoint of system's approach, especially focusing on planning/programming procedures, organizational structure and business process re-engineering. The author analyzed current projects and plans on the field of Korea defense information systems, for finding what kinds of problems and why the problems occurred. The author concluded that many problems came from wrong approach of previous information resource management. Highlights of the proposed model are as follows: 1) Planning and programming structure must be considered as a major information resources and it must be managed as a key role through the whole system life cycle; 2) Organizational structure should be properly set up for managing and implementing information system projects; 3) Business process should also be analyzed thoroughly for re-engineering and innovating current inefficient organizational structure. These three additional viewpoints added to previous model for improving Korea defense information resource management.

• 한국산업정보학회:학술대회논문집
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• 한국산업정보학회 1998년도 춘계공동학술대회 발표논문집 IMF시대의정보화 추진전략
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• pp.191-197
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• 1998

IMF 체제와 의료시장 개방 체제속에서 경쟁우위와 합리적인 경영환경을 구축하기 위해서는 의료업계에서도 불합리한 구조적 개선과 다변화하는 고객서비스 개선을 위해 병원 조직의 효과성 또는 경영 합리화를 위해 구조조정이 불가피하다. 변화의 대응전략 하나로정보기술(Information Technology)에 의한 HPR(Hospital Process ReEngineering) 방법론을 적용시켜 조직의 리스트럭처링(Restructuring)과 프로세스 리엔지니어링(Process ReEngineering)개선으로 인한 경영환경 변화요인을 분석함으로써 기대되는 학습조직, 유연조직, 가상조직, 네트워크 조직, 인간존중조직의 구성효과와 서비스의 질적 향상, 조직의 재구성, 업무의 재분배,인적자원의 적재적소 배치, 사무환경개선, 업무처리과정이 표준와, 경영환경 개선의 기대효과와 정보기술은 단순한 프로세스의 개선, 효율화가 아니라 새로운 환경에 적합한 최적의 경영도구로 병원의 목적 달성에 간접적이 아닌 직접적인 도움을 주는 성공요인으로 평가하였다.

• 인터넷정보학회논문지
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• 제9권2호
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• pp.139-145
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• 2008

CRM(Customer Relationship Management)은 비즈니스 환경에서 기업의 이익과 경쟁적 우위를 차지할 수 있도록 하는 비즈니스 전략이다. 기업의 고객 응대 기법으로는 인터넷, E-mail, SMS(Short Message Service), 텔레포니 서비스, DM(Direct Mail)이 이용되고 있다. 최근 수익성 모델 향상을 위한 노력으로 기존 고객의 이탈 방지 및 유지, 신규 고객의 가입 및 유지를 통한 비즈니스 모델을 다각화하고 있다. 또한 고객의 최초 접점이 될 수 있는 CRM 센터의 업무 프로세스 재설계(Business Process Re-engineering), 업무 프로세스 관리(Business Process Management)가 빈번하게 발생하고 있다. 본 논문에서는 고객응대 CRM 모델 구축시의 고려 사항을 제시하고 콜 객체 라우팅(Call Object Routing)을 위한 에이젼트(Agent)를 제안하고 구현 및 성능평가를 하였다. 제안한 모델은 대 고객 응대 CRM 모델로 효율적으로 이용될 수 있다.