신뢰성 지수에 의한 위상최적화

임민규,박재용,황승민,오영규,박재용,한석영 한국공작기계학회 2009 한국공작기계학회 춘계학술대회논문집 Vol.2009 No.-

The objective of this work is to integrate reliability analysis into topology optimization problems. The reliability index determines design domain and uncertainty value. The elemental sensitivity numbers are calculated from finite element analysis and then converted to the nodal sensitivity numbers in the design domain. A mesh-independency filter using nodal variables is introduced to determine the addition of elements and eliminate unnecessary structural details below a certain length scale in the design. To further enhance the convergence of the optimization process, the accuracy of elemental sensitivity numbers is improved by its historical information. Application of the RBTO model gives a different topology relative to DTO. It is found that the RBTO model yields more reliable optimal topologies than those produced by DTO.

지역사회 봉사와 이용률 증대를 위한 복합교회건축에 관한 연구 : 교회와 교육시설의 복합건축을 중심으로 focused on the Church and Education Complex Building

임영호,박재승 대한건축학회 2003 대한건축학회 학술발표대회 논문집 - 계획계/구조계 Vol.23 No.1(계획계)

The purpose of this study was to propose the model of the church and education complex building. Church is the body of Jesus Christ and called and sent to serve others. Jesus showed his way of life as a sample of churches. But contemporary churches do not follow that sample, so churches need to be renewed. Current issues on the contemporary church are 'serving community', 'raising efficiency', 'focusing on other that worship space', 'raising flexibility' and etc. This study was focused on the 'serving community' and 'raising efficiency'. Preceded researches and books were the foundation of this study and several churches were samples of this study. Through this study, church and education complex building can be realized to be the good model of sound churches.

CFRP 복합적층판의 적층배향·계면수에 따른 저속충격특성

임광희,박노식,나승우,김영남,이현,심재기,양인영 한국공작기계학회 2001 한국생산제조학회지 Vol.10 No.6

In this paper, this study aims at the evaluation on the characteristics of CFRP laminate plates using a falling weight impact tester. The experiment was conducted on several laminates of different orientation. A system was built for measuring the impact strength of CFRP laminates in consideration of stress wave propagation theory using a falling weight impact tester. Delamination areas of impacted specimens for the different ply orientation were measured with ultrasonic C-scanner to find correlation between impact energy and delamination area. Absorbed energy of quasi-isotropic specimen having four interfaces was higher than that of orthotropic laminates with two interfaces. The more interfaces, the greater the energy absorbed. The absorbed energy of a hybrid specimen containing a GFRP layer was higher than that of normal specimens.

적응 루프법을 이용한 진화적 구조 위상 최적설계

황승민,박재용,임민규,오영규,한석영 한국공작기계학회 2009 한국공작기계학회 춘계학술대회논문집 Vol.2009 No.-

This paper presents a reliability-based topology optimization (RBTO) using bi-directional evolutionary structural optimization (BESO). Topology optimization is formulated as volume minimization problem with probabilistic displacement constraint. Young's modulus, external load and thickness are considered as uncertain variables. In order to compute reliability index, four methods, i.e., RIA, PMA, SLSV and ADL(adaptive-loop), are used. Reliability-based topology optimization design process is conducted to obtain optimal topology satisfying displacement and reliability index constraints with the above four methods, and then each result is compared with respect to numerical stability and computing time.

순차적 크리깅기법을 이용한 미소혼합기의 최적화

박재용,유진식,황승민,임민규,오영규,김용대,한석영,맹주성 한국공작기계학회 2008 한국공작기계학회 추계학술대회논문집 Vol.2008 No.-

An active micro-mixer, which is composed of an oscillating micro-stirrer in the micro-channel to provide effective mixing was optimized. The effects of molecular diffusion and disturbance by the stirrer were considered with regard to two types of mixer models: the simple straight micro-channel and micro-channel with an oscillating stirrer. Two types of mixer models were studied by analyzing mixing behaviors such as their interaction after the stirrer. The mixing was calculated by Lattice Boltzmann methods using the D2Q9 model. In this study, the time-averaged mixing index formula was used to estimate the mixing performance of time-dependent flow. The mixing indices of the two models were compared. From the results, it was found that the mixer with an oscillating stirrer was much more enhanced' and stabilized. Therefore, an approximate optimization of an active micro-mixer with an oscillating stirrer was performed using Kriging method with OLHD (Optimal Latin Hypercube Design) in order to determine the optimal design variables. The design parameters were established as the frequency, the length and the angle of the stirrer. The optimal values were obtained as 1.5754, 0.803D and ±45°, respectively. It was found that the mixing index of the optimal design increased by 83.36% compared with that of the original design.

임신 제 일삼분기와 제 이삼분기 초음파의 태아기형 진단의 유용성에 대한 고찰

최승도,최규연,이정재,정성윤,이임순,이권해 순천향의학연구소 2003 Journal of Soonchunhyang Medical Science Vol.9 No.2

Objective: Ultrasonographic screening between 9 and 13 weeks for fetal structural abnormalities using transvaginal sonography in unselected population. Visualization of detailed fetal anatomy in the first trimester has improved as a result of technological progress in ultrasound machines and the introduction of transvaginal sonography(TVS). Our study aims to evaluate the accuracy of TVS as a screening tool for detecting fetal malformations in a nonselected population of pregnant women. For this purpose we compared the results obtained by using second trimesster TA scanning with those obtained using TVS at 9-14 weeks' gestation. Methods: From March 2001 to February 2003, 620 unselected consecutive pregnant women were recruited at their initial visit at Soonchunhyang university hospital, department of obstetrics and gynecology and offered a TVS scan at the average gestational age of 9-13 weeks in addition to the TA screening usually performed between 22-26 weeks. To fulfill the technical requirements of a screening test, ultrasonographic examinations were performed by skillful operators with different degrees of experienced using adequate instruments Aloka SSD 5500 (Aloka Co. Ltd., Tokyo, Japan) provided with either a 3.5-5MHz TA probe or a 5-7.5MHZ TV probe) in a fixed scanning time of maximum 30 min, generally considered sufficient for a complete fetal anatomic survey. Results: During the study period we found in our unselected population an overall prevalence of target abnormalities of 2.2%(24 malformed fetuses out of 600 screened). In the fetuses examined by TVS, 16 abnormalities were detected whereas 8 were not; of these, 6 were detected at transabdominal rescreening at 22-26 weeks and the remaining 2 were observed after birth. A nuchal region abnormality was the most frequent type of malformation detected in the early scan, including six cases of nuchal edema, two cases of cystic hygroma associated with hygroma associated with hydrops, three cases of hydronephrosis, one case of fetal neck teratoma, one case of cleft lip. Conclusion: This study has demonstrated the potential of screening a low risk population for fetal abnormalities at 9-13 weeks of gestation using transvaginal sonography and rescreened via transabdominal sonography at 22-26 weeks. Larger studies are required to establish the clinical value of the first trimester scan.

갱년기 여성의 호르몬 대치 요법에 대한 수용율

이임순,장진영,이정재,이순곤,이권해,이해혁,김승형 순천향의학연구소 1997 Journal of Soonchunhyang Medical Science Vol.3 No.2

Purpose: We have evaluated the compliance of hormone replacement therapy. Method: There are 185 climacteric women who are divided into three groups (Group I, Group II, Group III). Group I is given conjugated equine estrogen(CEE, 0.625mg, day 1-30) plus medroxyprogesterone acetate(MPA, 5mg, day 1-12). Group II is given conjugated equine estrogen (CEE, 0.625mg, day 1-30) plus medroxyprogesterone acetate (MPA, 2.5mg, day 1-30), Group III is given only conjugated equine estrogen(CEE, 0.625mg, day 1-30). Results: 1) The compliance rate of hormone replacement therapy during three months is 77.9% including each Group I : 77.7%, Group Ⅱ : 76.1%, Group Ⅲ :80.4%. 2) The compliance rate of hormone replacement therapy during six months is 60.7% including each Group Ⅰ:52.9%, Group Ⅱ: 56.4%, Group Ⅲ: 79.5%. 3) The compliance rate of hormone replacement therapy during nine months is 49.7% including each Group Ⅰ: 45.5%, Group Ⅱ:41.7%, Group Ⅲ: 64.3%. 4) The compliance rate of hormone replacement therapy during a year is 44.4% including each Group Ⅰ: 40.2%, Group Ⅱ:35.3%, Group Ⅲ: 59.5%. Conclusion : It is vital that we maximize compliance if patients are to receive the full benefits from hormone replacement therapy. We think that physicians who prescribe hormone replacement therapy for climacteric women should enough explain the purpose, risks, and side effect of treatment for maximizing compliance of hormone replacement therapy.

반복가열냉각에 의한 수화시멘트 페이스트와 골재 분리 방법

김세훈,임승준,안재철,오상균,김정길 대한건축학회 2003 대한건축학회 학술발표대회 논문집 - 계획계/구조계 Vol.23 No.2(구조계)

Cement mortar and efficient disconnection of aggregate are indispensable for recycling of waste concrete, and the problem is with quality in the existing physical disconnection way, and the problem has been by application of a concrete recycling construction materials. Specially, in case of recycled aggregate, the quality is lowered because of the fine aggregate powder which has a bad influence on flowability, a compression strength by adhesion of mortar on the aggregate face, and the case of recycled cement was added to during recycle cement. Therefore, a mortar and interfacial separation of aggregate are large in proper quality for concrete recycling is expected that affect. This study based on the recycled cement manufacturing way which used an aggregate interfacial separation of waste mortar in this study so that the coefficient of thermal expansion of hardend cement paste and an the coefficient of thermal expansion of a fine aggregate are different in a recycled cement manufacturing way, but leaves a purpose.

반도체 미립자를 함유한 Silica Glass의 제조 및 특성

류봉기,이승한,임재호 釜山大學校生産技術硏究所 1998 生産技術硏究所論文集 Vol.55 No.-

본 연구에서는 Sol-Gel법을 이용하여 우수한 양자 사이즈 효과를 가진 ZnS를 함유한 실리카 유리를 제조하였다. 출발 물질로서 Si(OC₂H)₄와 Zn(CH₃COO)₂·2H₂O를 사용하여 무색 투명한 겔을 제조하였다. 얻어진 겔을 600℃에서 열처리를 하여 상온에서 H₂S gas와 반응시켜 유리 내에 ZnS 미세결정을 형성시켰다. ZnS 미립자의 밴드갭 에너지 3.71∼4.27eV였는데 이 값은 벌크상 ZnS의 밴드갭보다 약 0.1∼0.5eV 더 높은 수치를 나타내었다. ZnS 미세결정의 크기는 EMA(Effective Mass Approximation)에 의해 구하였는데, 이는 ZnO의 투여량과 H₂S gas와의 반응시간에 따라 변화하였다. ZnS 미세결정의 크기가 증가함에 따라, 광흡수단은 낮은 에너지영역으로 이동하였는데, 이 현상은 양자 사이즈 효과를 보여주고 있다. In this study, Sol-Gel process has been applied to make ZnS-doped silica glass having a significant quantum size effect. Si(OC₂H)₄ and Zn(CH₃COO)₂·2H?O were used to prepare transparent and colorless gels. These gels were heated at 600℃, then reacted with H₂S gas to form fine ZnS microcrystals in glasses. The opical band gap of the ZnS microcrystals was 3.71∼4.27eV, which was 0.1∼0.5eV higher than that of bulk ZnS crystal. The size of ZnS microcrystals calculated by EMA(Effective Mass Approximation) in glasses changed with ZnO concentration and H₂S gas reaction time. As the size of the ZnS microcrystal increased, the absorption edge of spectra shifted to the low-energy side, thus providing quantum size effect.

운동제어의 신경생리학적 기초

정성태,홍승길,임재형 師範大學 體育硏究所 1994 서울大學校 體育硏究所論集 Vol.15 No.2

Many motor activities of animals and human beings are a critical aspect for their survival. Although it has not been clearly understood how motor activities are produced, the idea that various motor programs exist somewhere in the central nervous system (CNS) is generally accepted. As evidence for existence of motor programs in the CNS, we may consider a simple, repetitive movement like walking. Walking does not require continuous thinking. Once it is initiated, it becomes quite automatic. If we try to control consciously our automated movement, then it becomes so unnatural. Edward Evart, a neurophysiologist, noticed in his monkey experiments that the arm muscle contraction for handle movement was preceded by the activation of neurons in the motor cortex that governs the arm movement. These experimental results may be taken as evidence for existence of central programs for movements in the motor cortex. Many other studies, however, have indicated that cerebellum is an important structure where motor program are stored. Potentially, motor programs may not be restricted to a particular site in the CNS. Instead, they may be distributed in the cortex. cerebellum and other neural structures such as the basal ganglia. To understand movements at the neural level, we should determine how movements are coded in the CNS. More specifically, we may have to reveal how neurons are interconnected and how they communicate with each other to ultimately produce movements. An important thing to realize before we attempt to answer these questions is the fact that there is no clear-cut boundary between voluntary and involuntary movements. Even in the voluntary activities such as tennis game, there are lots of involuntary components. Also, in many other cases, there is good evidence that perfect movements can be achieved involuntarily. Diving, which requires a rapid, coordinated control of eyes, arms, legs and other parts of the body, is a good example. To perform this type of movement, there must be a motor program. Cerebellum has been indicated as a key structure necessary for this kind of program. Cerebellum is known as a site involved in the control of independent limb movements, especially rapid, skilled movements. Such movements are initiated by neurons in the frontal association cortex, which control neurons in the primary motor cortex. Both the frontal association cortex and the primary motor cortex send information about intended movements to the cerebellum. Information from the somatosensory system, which informs about the current position and rate of the movement of the limbs-information necessary for computing the details of a movement-is also sent to the cerebellum. When the cerebellum receives the information that the motor cortex has begun to initiate a movement, it computes the contribution that various muscles will have to make to perform that movement. The result of this computation is sent back to the motor cortex. Thus, the information from the cortex enables the cerebellum to modify the ongoing movement initiated by the frontal cortex. The capacity of the cerebellum to fine-tune motor drive generated in the motor cortex may be enhanced by training. In this case, the training will influence the involuntary components of movement.