• 대한산업공학회지
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• 제15권1호
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• pp.1-15
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• 1989

In the past few years, increasing numbers of automatic storage/retrieval system (AS/RS) using computer controlled storage/retrieval machine have been installed. This paper introduces two modeling approaches to determine the best operating policy for AS/RS : an M/G/1 queueing model and a computer simulation model. The operating policy consists of three elements. : the operation command cycle, the storage location method, and the operation dispatching rule. The analysis based on M/G/1 model is suitable for a quick and approximate evaluation, due to its inherent strict assumptions. The computer simulation can be used to perform a more realistic analysis. It is shown through the study that a significant improvement in the throughput and/or the space requirement can be expected by determining the best operating policy to a particular system. Most important, the computer simulation demonstrates its powerful capability in evaluating dynamic stochatic systems with imperfect information.

• 대한산업공학회지
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• 제16권1호
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• pp.99-106
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• 1990

With two-class-based storage assignment policy and dual command cycle in Automated Storage/Retrieval Systems(AS/RS), the problem of determining the region dedicated for class-one item is considered. First, the expected travel time of the S/R machine is derived when the boundary of the class-one region is square. Secondly, a heuristic procedure is proposed which determines sequentially the class-one region in a discrete rack. An application of the procedure generates leaf shape region which confirms that the L-shape partition is not necessarily optimal.

• Journal of Electrical Engineering and Technology
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• 제13권3호
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• pp.1223-1231
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• 2018

The direct torque control (DTC) scheme features a simple structure thanks to stator flux-oriented control. It has the advantage of robustness against motor parameters variation since only the stator resistance is involved in the control scheme. On the other hand, the disadvantage of DTC is large torque ripple. To reduce the torque ripple, many studies on DTC-space vector modulation (DTC-SVM) schemes, which modulate the duty ratio with a fixed switching cycle, have been proposed. However, there is the difficulty in obtaining the duty ratio for DTC-SVM. Hence, this paper proposes a new duty ratio selection and stator flux calculation methods for reducing torque ripple. Simulations and experiments were carried out to determine the validity of the proposed method. The proposed scheme has simplified the duty ratio command and achieved the same control performance as the conventional duty ratio modulation method without using the information of motor parameters.

• 해양환경안전학회지
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• 제30권4호
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• pp.332-339
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• 2024

안전은 해군과 같은 위험성이 높은 환경에서 활동하는 조직에게 필수적이다. 효과적인 안전관리는 지속적인 개선과 보완을 통해 유지되어야 하며, PDCA cycle을 활용하는 것이 일반적이다. 하지만 해군에서는 안전 규정 강화와 교육 확대에도 불구하고 안전사고가 지속적으로 발생하고 있다. 이는 안전사고 분석 및 분류 시스템 개선의 필요성을 보여준다. 본 연구에서는 해군 안전사고 분류체계를 분석하고 문제점을 파악하여 효과적인 분류체계를 구축하는데 중점을 두었다. 이를 통해 안전사고 결과를 데이터화하고, 사고의 근본 원인을 파악하며, 중장기적인 안전관리 정책 수립에 기여할 수 있도록 12자리의 해군 안전사고 분류 코드를 제안하였다.

• 한국산학기술학회논문지
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• 제19권3호
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• pp.638-647
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• 2018

우리는 현존하는 북한의 위협과 미래에 예상되는 잠재적 위협에 대비해야 한다. 이를 위해 우리는 자원을 효율적으로 활용하여 전쟁에서 승리할 수 있는 군사력 건설에 노력하여야 한다. 무기체계는 획득단계에서 소요군에서 요구한 작전운용성능(ROC)의 지속성을 기본으로 전투준비태세를 유지하고 작전지속지원능력을 보장할 수 있어야 한다. 이를 달성하기 위해서는 무기체계 획득에서 경제적이고 효율적인 창정비를 수행할 수 있도록 소요제안에서부터 창정비요소를 개발하는 과정의 정립이 중요하다. 경제적이고 효율적인 창정비를 수행하기 위한 창정비 요소를 개발하는 과정은 첫째, 소요제안에서부터 창정비 필요성을 검토하여 개략적인 창정비요소가 포함되어야 한다. 소요제기서를 토대로 장기소요결정을 통하여 선행연구에서 창정비요소 개발개념을 발전시켜야 하겠다. 둘째, 체계개발 단계에서 창정비요소를 개발할 수 있는 최초의 문서인 창정비 개발계획안을 작성하여야 한다. 창정비개발계획안은 입증시험과 확증시험을 통한 검증이 필요하다. 셋째, 체계개발 이후 검증된 창정비개발계획안에 따라 적시에 각 군의 군수사령부에서는 창정비 방침(안)과 창정비 요소개발 중기 소요제기(안)을 작성하여 보고되어야 한다. 또한 체계개발 시 검증된 창정비개발계획안은 창정비요소가 개발완료 될 시점까지 구체화되고 최신화 되어져야 한다. 창정비요소를 개발하는 과정의 정립은 적의 위협이 존재하고 자원이 부족한 우리의 현실에서 경제적이고 효율적인 군사력을 건설하는데 기여할 것이다.

• Asian Pacific Journal of Cancer Prevention
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• 제14권7호
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• pp.4421-4426
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• 2013

Objective: The present study employed 5-aza-2'-deoxycytidine (5-Aza-CdR) to treat non-small cell lung cancer (NSCLC) cell line A549 to investigate the effects on proliferation and expression of the TFPI-2 gene. Methods: Proliferation was assessed by MTT assay after A549 cells were treated with 0, 1, 5, 10 ${\mu}mol/L$ 5-Aza-CdR, a specific demethylating agent, for 24, 48 and 72h. At the last time point cells were also analyzed by flow cytometry (FCM) to identify any change in their cell cycle profiles. Methylation-specific polymerase chain reaction (MSPCR), real time polymerase chain reaction(real-time PCR) and western blotting were carried out to determine TFPI-2 gene methylation status, mRNA expression and protein expression. Results: MTT assay showed that the growth of A549 cells which were treated with 5-Aza-CdR was significantly suppressed as compared with the control group (0 ${\mu}mol/L$ 5-Aza-CdR). After treatment with 0, 1, 5, 10 ${\mu}mol/L$ 5-Aza-CdR for 72h, FCM showed their proportion in G0/G1 was $69.7{\pm}0.99%$, $76.1{\pm}0.83%$, $83.8{\pm}0.35%$, $95.5{\pm}0.55%$ respectively (P<0.05), and the proportion in S was $29.8{\pm}0.43%$, $23.7{\pm}0.96%$, $15.7{\pm}0.75%$, $1.73{\pm}0.45%$, respectively (P<0.05), suggesting 5-Aza-CdR treatment induced G0/G1 phase arrest. MSPCR showed that hypermethylation in the promoter region of TFPI-2 gene was detected in control group (0 ${\mu}mol/L$ 5-Aza-CdR), and demethylation appeared after treatment with 1, 5, 10 ${\mu}mol/L$ 5-Aza-CdR for 72h. Real-time PCR showed that the expression levels of TFPI-2 gene mRNA were $1{\pm}0$, $1.49{\pm}0.14$, $1.86{\pm}0.09$ and $5.80{\pm}0.15$ (P<0.05) respectively. Western blotting analysis showed the relative expression levels of TFPI-2 protein were $0.12{\pm}0.01$, $0.23{\pm}0.02$, $0.31{\pm}0.02$, $0.62{\pm}0.03$ (P<0.05). TFPI-2 protein expression in A549 cells was gradually increased significantly with increase in the 5-Aza-CdR concentration. Conclusions: TFPI-2 gene promoter methylation results in the loss of TFPI-2 mRNA and protein expression in the non-small cell lung cancer cell line A549, and 5-Aza-CdR treatment could induce the demethylation of TFPI-2 gene promoter and restore TFPI-2 gene expression. These findings provide theoretic evidence for clinical treatment of advanced non-small cell lung cancer with the demethylation agent 5-Aza-CdR. TFPI-2 may be one molecular marker for effective treatment of advanced non-small cell lung cancer with 5-Aza-CdR.

• 한국국방경영분석학회지
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• 제36권2호
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• pp.39-52
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• 2010

미 국방성은 플랫폼중심전의 상향식소요제기에서 네트워크중심전의 하향식소요제기로 변화하고 능력기반전력구조개발에 힘쓰고 있으며, 한국군도 다변화하는 안보위협과 전시작전권전환을 앞두고 능력기반전력구조로의 전환을 시도하고 있으나 통합능력의 개념과 개발방법이 부족한 상태이다. 따라서 이 연구는 능력기반전력구조 개발을 위해 상 하위 조직 전체의 능력과 현재의 전력운용관점과 미래의 전력개발관점을 동시에 포함하는 통합능력프레임워크를 제시한다.

• 한국CDE학회논문집
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• 제13권5호
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• pp.334-341
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• 2008

Computer-aided engineering (CAE) analysis is considered essential for product development because it decreases the simulation time, reduces the prototyping costs, and enhances the reusability of product parts. The reuse of quality-assured CAE data has been continually increasing due to the extension of product lifecycle management; PLM, which is widely used, shortens the product development cycle and improves the product quality. However, less attention has been paid to systematic research on the interoperability of CAE data because of the diversity of CAE data and because the structure of CAE data is more complex than that of CAD data. In this paper, we suggest a CAE data exchange method for the effective sharing of geometric and analysis data. The method relies on heterogeneous CAE systems, a virtual reality system, and our developed CAE middleware for CAE data exchange. We also designed a generic CAE kernel, which is a critical part of the CAE middleware. The kernel offers a way of storing analysis data from various CAE systems, and, with the aid of a script command, enabling the data to be translated for a different system. The reuse of CAE data is enhanced by the fact that the CAE middle-ware can be linked with a virtual reality system or a product data management system.

• 한국시뮬레이션학회논문지
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• 제12권4호
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• pp.25-40
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• 2003

With the growing usage of the networks, the world-wide Internet has become the main means to exchange data and carry out transactions. It has also become the main means to attack hosts. To solve the security problems which occur in the network such as Internet, we import software products of network security elements like an IDS (Intrusion Detection System) and a firewall. In this paper, we have designed and constructed the general simulation environment of network security model composed of multiple IDSes and a firewall which coordinate by CNP (Contract Net Protocol) for the effective detection of the intrusion. The CNP, the methodology for efficient integration of computer systems on heterogeneous environment such as distributed systems, is essentially a collection of agents, which cooperate to resolve a problem. Command console in the CNP is a manager who controls the execution of agents or a contractee, who performs intrusion detection. In the network security model, each model of simulation environment is hierarchically designed by DEVS(Discrete Event system Specification) formalism. The purpose of this simulation is that the application of rete pattern-matching algorithm speeds up the inference cycle phases of the intrusion detection expert system and we evaluate the characteristics and performance of CNP architecture with rete pattern-matching algorithm.

• 한국산학기술학회:학술대회논문집
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• 한국산학기술학회 2003년도 Proceeding
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• pp.197-206
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• 2003

With the growing usage of the networks, the world-wide Internet has become the main means to exchange data and carry out transactions. It has also become the main means to attack hosts. To solve the security problems which occur in the network such as Internet, we import software products of network security elements like an IDS (Intrusion Detection System) and a firewall. In this paper, we have designed and constructed the General Simulation Environment of Network Security model composed of multiple IDSes and a firewall which coordinate by CNP (Contract Net Protocol) for the effective detection of the intrusion. The CNP, the methodology for efficient integration of computer systems on heterogeneous environment such as distributed systems, is essentially a collection of agents, which cooperate to resolve a problem. Command console in the CNP is a manager who controls tie execution of agents or a contractee, who performs intrusion detection. In the Network Security model, each model of simulation environment is hierarchically designed by DEVS (Discrete EVent system Specification) formalism. The purpose of this simulation is to evaluate the characteristics and performance of CNP architecture with rete pattern matching algorithm and the application of rete pattern matching algorithm for the speeding up the inference cycle phases of the intrusion detection expert system.