• The Korean Journal of Rheology
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• v.10 no.2
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• pp.74-81
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• 1998

사출성형품의 설계는 그 내부의 기계적 물성 변화보다는 전통적으로 용도에 부합하 는 형상을 위주로 하여 이루어져 왔기 때문에 설계조건의 개선을 통하여 성능이 우수한 제 품을 얻기까지 많은 시행착오가 요구되고 있다. 그런데 사출성형 실험이나 물성평가 시험을 하기 전에 성형품의 부위별 기계적 물성을 알수있다면 제품의 설계나 금형 설계에 많은 도 움이 될 수 있으므로 최근에 물성 예측을 위한 방법론들의 개발이 다양하게 시도되고 있다. 따라서 본 연구에서는 학습시스템, 사출성형 수치모사와 기계적 물성과의 상관관계를 밝히 는 방법을 만들어 사출물이 제작되기 전에 그들의 기계적 물성을 사출성형 수치모사에서 얻 어진 열적·기계적 이력으로부터 예측하고자 하였다. 이때 성형품의 기계적 물성과 열적· 기계적 이력 사이에는 매우 복잡하고 비선형적인 상관관계를 보이기 때문에 이들 사이를 비 매개변수적으로 연관짓기 위하여 역전파 인공신경망 알고리듬을 사용하였으며 열적·기계적 이력은 사출성형용 수치모사 소프트웨어를 이용하여 구하였다. 학습과정에서 전역최소값에 도달하지 못하는 인공신경망의 문제점을 해결하기 위하여 모멘텀변수와 잡음지수를 포함하 는 일련의 항을 첨가하여 연결가중치를 보정하였다. 그 결과 어떤 초기값에 의하여 학습이 되더라도 전역최소값에 도달하는 것을 확인하였으며 이를 이용하여 다른 사출조건에서 사출 물의 기계적 물성을 잘 예측할수 있었다.

• Proceedings of the Korean Operations and Management Science Society Conference
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• 2005.05a
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• pp.899-903
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• 2005

eSCM의 확산은 기업의 경쟁 환경을 급변시키고 있다. 과거의 생산성 및 효율성을 통한 원가 절감과 품질 개선 중심에서 벗어나 시장수요를 신속하게 충족시키는 응답성 중심으로 변하고 있다. 이는 고객이 요구하는 제품, 가격 및 조건에 관계없이 최소의 비용으로 신속하게 고객에게 가치를 제공하는 것이다. 이렇게 eSCM의 확산이 빠르게 진행되고 있지만 공급체인의 한 구성원인 제조부문과는 아직도 정보 흐름의 공유가 잘 이루어지지 않고 있는 실정이다. 불확실한 수요예측은 재고품절을 발생시키며 고객들의 주문취소나 많은 품절 비용을 초래하게 된다. 따라서 본 연구에서는 조정 에이전트 기반으로 고객과 제조자와 공급자 간의 조정을 통해 최소비용으로 주문량에 대해 분할 납품을 제시하고 그에 따른 비용을 산출하여 그 비용만큼 할인혜택을 부여함으로써 고객만족도와 비용측면을 비교 검증한 모델을 제시한다.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.11 no.1
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• pp.12-17
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• 2018

This study describes the design and implementation of Antenna for Digital Satellite Communication. The Antenna unit for SHF band consists of Reflector, Septom Polarizer, Feed Horn and Support Frame etc. Thought analysis of space environment before production, the possibility of the malfunction of equipment minimized and we designed a reliable Antenna through simulation for vibration and thermal analysis generated during the launch, and compared pre-simulation of main performance results to test results about main performances of Antenna after production. After fabricating the antenna, the maximum gain of the antenna main beam is 36.5dBi, which satisfies the requirement of 35dBi or more, and it also satisfies the requirement of -20dB for return loss of less than -24dB. Also, the isolation of the transmission and reception of the antenna is -22.6dB or less, which satisfies the requirement of -20dB or less. The antenna for digital satellite communication described in this paper can be used in the satellite field of geostationary earth orbit and low earth orbit requiring high reliability in the future.

• Journal of the Korea institute for structural maintenance and inspection
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• v.21 no.6
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• pp.1-9
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• 2017

Spiral reinforcement in a circular column plays an effective role in the ductile behavior of a column through position fixing and buckling restraining of the longitudinal reinforcement, and confining core-concrete. Each country has suggested the minimum volumetric ratio of spiral reinforcement in order to secure the ductility of concrete columns. The minimum volumetric ratio of spiral reinforcement suggested by ACI 318-14 and the national concrete structure design standard was developed based on the theory of Richard et al. (1928); furthermore it has been used until now. However, their theory cannot consider the effects of high strength concrete and high strength reinforcement, and arrangement condition of the spiral reinforcement. In this study, a modified minimum volumetric ratio equation is suggested, which is required to improve the ductility of reinforced concrete circular columns and to recover their stress. The modified minimum volumetric ratio equation suggested here considers the effect of the compressive strength of concrete, the yield strength of spiral reinforcement, the cross sectional area of columns, the pitch of spiral reinforcements and the diameter of spiral reinforcement. In this paper, the validity of the minimum volumetric ratios from ACI 318-14 and this study was investigated and compared based on the results of uniaxial compression experiment for specimens in which the material strength and the spiral reinforcements ratio were used as variables. In the end of the study, the modification method for the suggested equation was examined.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.31 no.5
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• pp.251-258
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• 2018

In construction site, conventional methods such as jackhammer or explosive methods(dynamite) have been often used for the demolition of structures. Use of those methods are more carefully treated in environmentally and historically sensitive area. For those reasons, use of Soundless Chemical Demolition Agent(SCDA) is getting the spotlight. The SCDA is a powder which has expansive strength when it is mixed with water. In these Characteristics, SCDA can destroy the concrete or rock as it is poured into boreholes of the concrete or rock structures. However, there is no industrial standard for the use of SCDA effectively yet. In this study, experimental study to measure the expansive pressure was conducted depending on various boundary conditions such as waterproof, length of the steel pipe, submerged of steel pipe. Furthermore, computational analysis using damage plasticity model to predict the minimum required pressure of the SCDA for the concrete demolition depending on spacing between holes(k-factor) and compressive strength of the concrete was conducted. Obtained results indicates that water heat dissipation with submerged steel pipe shows the stable pressure for measuring the SCDA and hole distance(k-factor) is the most important factor for crack initiation of concrete.

• Journal of the Korean Institute of Landscape Architecture
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• v.39 no.5
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• pp.57-75
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• 2011

The purpose of this study is to find ways of evaluating the suitability of sites being considered for development of different types of parks in the vicinity of yangmock-myun kyoung buk, where a large project(as large as about14.0$km^2$) has been planned. The results are as follows. Three surveys for selecting the assessment indicators were performed. ${\cdot}$ The first survey analyzed the importance of 23 selected assessment indicators based on a review of existing literature review and an on-the-spot research. ${\cdot}$ The second survey selected assessment indicators for each park type. ${\cdot}$ The third survey computed additive values of selected assessment indicators by the park types. It used a method of standardizing the average importance of indicators by making their sum equal to 10. These additive values were then multiplied by each grade of indicators to make a final evaluation. An evaluation of the site-suitability of park types was performed twice. The purpose of the first evaluation was to figure out how much each type met the minimum requirements targeted for all landscape types. The minimum requirements were derived by using a relative comparison between the standard of value rating of the assessment indicators, which was over the medium magnitude on the importance analysis, and the result of field research. A second evaluation estimated the targeted sites that met the minimum requirements. Value ratings of second assessment indicators were quantitatively divided as 1 to 3 grade and the evaluation scores were added, giving an additive value for each assessment indicator. The evaluation score on each park type was rated on a scale of 1 to 3 according to their averages, (from lowest to highest). Since this evaluation model of the site suitability on park types only focused on the 'face' of space in this study, additional analysis is necessary for setting the evaluation model and incorporating the overall impact of space, network connection and other factors, considering 'spot', 'line' and 'face' aspects of space.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.5
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• pp.557-564
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• 2017

The purpose of the thermal imaging observation device mounted on the K's tank in the Republic of Korea military is to convert infrared rays into visual information to provide information about the environment under conditions of restricted visibility. Among the various performance indicators of thermal observation devices, such as the view, magnification, resolution, MTF, NETD, and Minimum Resolvable Temperature Difference (MRTD), the MRTD is the most important, because it can indicate both the spatial frequency and temperature resolvable. However, the standard method of measuring the MRTD in NATO contains many subjective factors. As the measurement result can vary depending on subjective factors such as the human eye, metal condition and measurement conditions, the MRTD obtained is not stable. In this study, these qualitative MRTD measurement systems are converted into quantitative indicators based on a gray scale using imaging processing. By converting the average of the gray scale differences of the black and white images into the MRTD, the mean values can be used to determine whether the performance requirements required by the defense specification are met. The (mean) value can also be used to discriminate between detection, recognition and identification and the detectable distance of the thermal equipment can be analyzed under various environmental conditions, such as altostratus, heavy rain and fog.

• Microbiology and Biotechnology Letters
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• v.13 no.4
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• pp.391-395
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• 1985

In order to develope a protoplast fusion system for citric acid and SCP producing Candida lipolytica, the optimal conditions for the formation and regeneration of protoplast were examined and the protoplast fusion was performed. At the optimal conditions of growth phase and Zymolyase treatment, frequencies of protoplast formation were 98%. Approximately 20-30% of protoplasts were regenerated on the regeneration minimal medium containing 3% agar and 30mM $CaCl_2$ with the overlay of the same medium. The fusion frequencies, 4-5${\pm}$10$^{-4}$, were accomplished by the treatment of two nutritionally complementary auxotrophic protoplasts, L-14 ($lys^-$) and T-24 (X$30^-$), with 30% PEG 6000 containing 100mM $CaCl_2$ at $30^{\circ}C$ for 20 minutes.

• Journal of the Korean Society of Propulsion Engineers
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• v.10 no.2
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• pp.1-14
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• 2006

Present study examines the numerical issues of cell structure simulation for various regimes of detonation phenomena ranging from weakly unstable to highly unstable detonations. Inviscid fluid dynamics equations with $variable-{\gamma} $ formulation and one-step Arrhenius reaction model are solved by a MUSCL-type TVD scheme and 4th order accurate Runge-Kutta time integration scheme. A series of numerical studies are carried out for the different regimes of the detonation phenomena to investigate the computational requirements for the simulation of the detonation wave cell structure by varying the reaction constants and grid resolutions. The computational results are investigated by comparing the solution of steady ZND structure to draw out the minimum grid resolutions and the size of the computational domain for the capturing cell structures of the different regimes of the detonation phenomena.

• Proceedings of the Korean Information Science Society Conference
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• 2000.10c
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• pp.594-596
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• 2000

인터넷 환경에서 프록시(proxy)는, 효율적인 데이터의 전송을 위해 다양한 클라이언트 장치들과 WWW 서버들간의 다리역할을 수행한다. 특히, 최근의 인터넷 환경은 이미지 같은 복잡하고 대량의 크기를 갖는 데이터 전송을 많이 요구하고 있으므로, 클라이언트 환경에 맞는 최선의 화질과 최소의 지연시간을 갖도록 데이터를 변환하여 재전송하는 트랜스코딩(transcoding)이 중요시되고 있다. 본 연구에서는 트랜스코딩을 수행하는 다수의 프록시들이 존재할 때, 클라이언트의 요구(request)와 장치(device), 또는 네트워크의 여러 가지 조건에 가장 적합한 프록시를 선택할 수 있는 수리적인 모델을 제안한다. 이러한 수리적 모델은 경로연결(redirector)내에서 동작하는 알고리즘으로서, 예상되는 지연시간과 오버플로우의 가능성을 최소화할 수 있는 최선의 프록시를 클라이언트와 서버사이에 연결함으로서 이미지 전송에 있어서 더 큰 효과를 얻을 수 있다. 실험 결과, 전체적인 지연시간을 줄일 수 있을 뿐만 아니라 클라이언트에게 적절한 양과 질의 데이터 전송효과를 가진다.