• 한국자동차공학회논문집
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• 제17권1호
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• pp.72-79
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• 2009

Recently, the internal combustion engines have focused on reducing the $CO_2$ gas in order to cope with severe regulations for fuel economy. Therefore, various new technologies have been developed. Among them, cooling system is spotlighted because it has great effect on fuel economy. In this study, we measured the friction losses of engine parts according to engine speed and oil temperature. We also obtained optimized oil temperature which has the minimum friction losses. Then, we selected optimized oil temperature range and gave informations of friction losses for each engine parts. In addition, we analyzed relationship between coolant temperature and oil temperature by using engine performance test system. From this experiment, we obtained the database for relationship between coolant temperature and oil temperature. Then, we found the optimal temperature about engine oil. We analyzed BSFC and exhaust emissions by controlling the high coolant temperture. If we controlled coolant temperature more higher, BSFC has a little difference but exhaust emissions such as THC and CO have reduced. By using these experimental results, we predicted that IC engine have more low fuel consumption and exhaust emissions by optimized cooling control strategy.

• International Journal of Reliability and Applications
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• 제3권1호
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• pp.1-16
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• 2002

In reliability engineering, the bathtub-shaped hazard rates play an important role in survival analysis and many other applications as well. For the bathtub-shaped, initially the hazard rate decreases from a relatively high value due to manufacturing defects or infant mortality to a relatively stable middle useful life value and then slowly increases with the onset of old age or wear out. In this paper, we present a new two-parameter lifetime distribution function, called the Loglog distribution, with Vtub-shaped hazard rate function. We illustrate the usefulness of the new Vtub-shaped hazard rate function by evaluating the reliability of several helicopter parts based on the data obtained in the maintenance malfunction information reporting system database collected from October 1995 to September 1999. We develop the S-Plus add-in software tool, called Reliability and Safety Assessment (RSA), to calculate reliability measures include mean time to failure, mean residual function, and confidence Intervals of the two helicopter critical parts. We use the mean squared error to compare relative goodness of fit test of the distribution models include normal, lognormal, and Weibull within the two data sets. This research indicates that the result of the new Vtub-shaped hazard rate function is worth the extra function-complexity for a better relative fit. More application in broader validation of this conclusion is needed using other data sets for reliability modeling in a general industrial setting.

• 대한조선학회논문집
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• 제48권1호
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• pp.67-75
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• 2011

Pyomindaehwa is a study book written in Korean and it takes a form of an investigation document made up of a conversation between Chosen's castaways and an interpreter taking place in Naesirogawa and Satsuma on the south end of Kyushu, Japan in the 19th century. This book is in three volumes. Many terminologies such as timber parts, sail, rigging and equipment have been shown in the last volume, which is mainly about a repairing process of drifting ship. Especially, timber parts' terminologies including hull's term were schematized in Kumamoto Text(1854b). This study have attempted to find out Naval architectural clues helping estimate actual drifting ship's type and bulk on the evidence of the contents. Based on the studies, it is possible to presume the type of Korean boats and ships, which are similar with the ones from database of 21 traditional fishing boats in the report on Investigation of Korean fishing boats studied previously. This paper has shown the logical process of presumption of types of boats.

• 한국CDE학회논문집
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• 제15권4호
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• pp.297-305
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• 2010

Medical image acquisition techniques such as CT and MRI have disadvantages in that the numerous time and efforts are needed. Furthermore, a great amount of radiation exposure is an inherent proberty of the CT imaging technique, a number of side-effects are expected from such method. To improve such conventional methods, a number of novel methods that can obtain 3D medical images from a few X-ray images, such as algebraic reconstruction technique (ART), have been developed. Such methods deform a generic model of the internal body part and fit them into the X-ray images to obtain the 3D model; the initial shape, therefore, affects the entire fitting process in a great deal. From this fact, we propose a novel method that can generate a 3D vertebraic generic model based on the statistical database of CT scans in this study. Moreover, we also discuss a method to generate patient-tailored generic model using the facts obtained from the statistical analysis. To do so, the mesh topologies of CT-scanned 3D vertebra models are modified to be identical to each other, and the database is constructed based on them. Furthermore, from the results of a statistical analysis on the database, the tendency of shape distribution is characterized, and the modeling parameters are extracted. By using these modeling parameters for generating the patient-tailored generic model, the computational speed and accuracy of ART can greatly be improved. Furthermore, although this study only includes an application to the C1 (Atlas) vertebra, the entire framework of our method can be applied to other body parts generally. Therefore, it is expected that the proposed method can benefit the various medical imaging applications.

• 한국콘텐츠학회논문지
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• 제14권6호
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• pp.1-10
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• 2014

온라인 비즈니스의 활성화와 인터넷 모바일 기기의 발달을 통해, 불특정 다수의 민감한 사용자 데이터가 쉽게 노출 되고 있고, 개방된 비즈니스 환경에서 최근 민감한 개인정보의 유출 이슈가 자주 언급되면서 그 중요도 측면에선 데이터베이스의 보안기술의 도입은 기업의 최우선 과제가 되고 있다. 2011년 정부에서도 정보통신망법 상의 개인정보 보호 강화조치를 법률로 제정 이를 다양한 산업 군에 적용하고 있다. 기업은 개인정보의 보호를 위해 다양한 방안들을 마련해 이러한 규제를 준수하며 내부에 관리중인 개인정보에 대해 보안을 강화하기 위해 빠르게 보안 솔루션을 도입하고 있다. 이에 수많은 민감한 개인의 데이터들이 저장되어 사용되고 있는 데이터베이스 측면에서 이러한 규제를 준수하는 동시에 효과적으로 데이터 보안기술을 확보하기 위한 방안을 보안 아키텍처의 기술적인 측면에서의 구분과 보안 솔루션 도입 시 고려가 되어야 하는 아키텍처와 기능적인 부분들에 대해 본 논문은 제시하였다.

• 한국건설관리학회:학술대회논문집
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• 한국건설관리학회 2008년도 정기학술발표대회 논문집
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• pp.340-343
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• 2008

최근 국내 외의 건설업은 대형화 복잡화 되어 메가 프로젝트의 성격을 보인다. 메가 프로젝트는 단순 합의 개념으로는 추구할 수 없는 복합적이고 상호 조율된 가치를 추구하므로, 프로젝트 관리의 관점이 아닌 프로그램 관리 관점에서의 접근이 필요하다. 프로그램 관리는 '종합사업관리'로 볼 수 있으며, 효율적으로 프로그램 관리를 위해서는 종합적인 관점에서 신속하게 의사결정을 지원해야 한다. 그러나 기존의 업무 지원 방법으로는 이를 해결 할 수 없기 때문에 의사결정을 지원해줄 수 있는 도구가 필요하며, 전자매뉴얼이 이 역할을 해줄 것으로 기대된다. 그러나 이러한 장점에도 불구하고 시방서 및 법률 등의 시스템 외부 정보들의 변동성으로 인해서 전자매뉴얼에 대한 연구는 미비한 실정이었다. 그러므로 본 논문은 시스템 외부 정보들과 상호 호환될 수 있는 전자매뉴얼 개발에 대한 연구의 일환으로, 사업수행 과정 분석 결과를 반영한 시스템 프레임을 제시하고 이를 바탕으로 데이터베이스를 구축함으로써 건설분야 전자매뉴얼의 국내 도입에 일조 하고자 한다.

• 대한기계학회논문집
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• 제18권3호
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• pp.768-776
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• 1994

This paper describes computer-aided forging design for rib/web shaped parts. In manufacturing a part by means of forging process, the first step is to design the forging. This is done by modifying the given machined part geometry according to the requirements of the forging process. Traditionally, this is done by experienced forging designers using empirical forging design guidelines. Generally, it would be neither possible nor practical to develop a system which encompasses the design of all types of forgings. Accordingly, forging design can be simplified by considering critical two dimensional cross sections of the machined part geometry. This system is composed of three modules(process variable decision module, forging design module and redesign module) and each module is carried out in regular sequence. In the process variable decision module, first of all, the undercut is checked and modified, and then deep recesses and holes difficult to forge are eliminated. Also parting line, forging plane, forging plan view area, forging weight and maximum size(maximum height or width)are determined. In the forging design module, the magnitude of various allowances, draft angle, minimum web thickness, corner and fillet radius are determined and then geometry modification is performed. Finally, since the design rules and databases used in this system are based on parameters of the forging geometry, such as the trimmed forging plan area, forging weight, forging maxmum size, plausible estimates need to be made for these parameters. Therefore, in the re-design module, the design process is iterated until a satisfactory forging is obtained.

• Clinical and Experimental Pediatrics
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• 제61권8호
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• pp.231-238
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• 2018

Purpose: Wasting and underweight are the 2 main indicators of children's undernutrition. We aimed to estimate the prevalence of undernutrition at the national level in Iran. Methods: We performed a search for original articles published in international and Iranian databases including MEDLINE, Web of Science, Google Scholar, Scopus, CINHAL (Cumulative Index to Nursing and Allied Health Literature), Scientific Information Database, Irandoc, Iranmedex, and Magiran during January 1989-August 2017. Seven keywords, in English and Persian, including malnutrition, protein energy malnutrition, growth disorders, underweight wasting, weight loss, children below 5 years old, and children, were used to search the databases. Results: Finally, 17 articles were included in the meta-analysis, based on which the prevalence of underweight and wasting in Iranian children were estimated to be 11% and 5%, respectively. The prevalence rates of underweight among children in the central, western, southern, and northern parts of Iran and at the national level were 24%, 5%, 20%, 17%, and 6%, respectively. The prevalence rates of wasting in the central, western, southern, and northern parts of Iran and at the national level were 9%, 4%, 11%, 5%, and 4%, respectively. Conclusion: Although the prevalence of underweight and wasting in Iran was low, some parts of the country showed high prevalence. The main reason behind this difference in the prevalence of malnutrition may be due to the level of development in different regions.

• 대한전기학회논문지
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• 제39권10호
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• pp.1108-1120
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• 1990

본 논문에서는 소량 다품종 생산에서 FMS(Flexible Manufactturing System)의 공정제어를 위한 지능형 제어기를 설계하였다. 설계된 제어기는 최적화 기법과 경험적 생산 규칙을 통합하여 가공품의 적재 및 흐름이 제어되고 선정된 성능 평가 기준 지표를 최대로 만족할 수 있도록 한다. 최적화 기법에 의해 구현되는 제어 기능은 생산시스템의 가공용량을 초과하지 않는 범위내에서 가공품의 순시생산율을 계산한다. 생산규칙 구성에 따르는 경험적 제어를 위하여 지식베이스가 형성되고 순시생산율 및 현재의 공정 정보를 기반으로 최종 대안이 선정된다. 이 경우 지식 베이스에는 대안 심사, 결정수립 기준, 그리고 가공품의 흐름제어에 관한 규칙들을 대상으로, 그리고 데이타베이스는 공정 정보 관리, 수정 침 저장을 대상으로 각각 구축된다. 공정 정보를 이용하여 생산계획의 진행 상황을 도시하게 되는 글래픽 시뮬레이션이 수행되며, 설계된 제어기의 성능평가는 컴퓨터 시물레이션을 통해 검토된다.

• 대한치과교정학회지
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• 제30권2호
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• pp.245-260
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• 2000

본 연구는 인터넷상의 가상공간에 다양한 자료로 구성된 환자 증례를 통해, 교정을 배우고자 하는 임상의나 학생들의 교육에 필요한 멀티미디어 데이터베이스를 구축하기 위한 것이다. 이러한 시스템을 구현하기 위해서는 이미지 자료의 처리, computer network를 통한 빠른 정보처리 기능, 진단 분석법의 개발, 데이터베이스의 구축 기술, 데이터베이스와 인터넷과의 연계, 증례를 통한 교육방법론과 같은 기술적 문제점들이 있다. 진단과 치료계획을 위한 분석은 모델 분석과 두부방사선 사진분석으로 나누어 제공하였다. 모델분석법은 arch length discrepancy와 Bolton tooth ratio를 환자 정보란에 제공하였다. 두부방사선 사진분석은 초진란에 제공하였다. Cephalometric analysis ver 2.0과 Power Ceph pro 3.3.5를 이용하여 Tweed, Steiner, Jarabak분석법 등을 제공하였으나, 본문에서는 주로 Kim's analysis와 몇 가지 계측치를 추가하여 설명하였고, 나머지는 tracing란에서 제시하였다. 또한 치료 종료 후나 보정란에서 치료 전,후의 두부방사선 사진을 중첩해서 보여줌으로써 치료에 의한 효과를 직접 볼 수 있도록 하였다.