• 제어로봇시스템학회논문지
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• 제12권9호
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• pp.945-953
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• 2006

Though a fully thermally coupled distillation column consumes less energy than an original column, it is not widely implemented in practice due to its operational difficulty. A new fully thermally coupled distillation column is proposed for the operability improvement, and its performance is investigated. The main improvement is the separation of a main column to give an upper and lower columns and the installation of an intermediate heat exchanger between them to regulate the fluctuation of product compositions. A proper manipulation of column pressure in the separated main columns made easy vapor flow without a compressor. The operability improvement is examined in a hexane process from the dynamic simulation using a commercial design software HYSYS. The simulation results indicate that the coupling among inputs and outputs is loosened to make easy manipulation of product compositions in the proposed distillation system.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2001년도 춘계학술대회논문집A
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• pp.644-651
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• 2001

The purpose of this study is to develop the improvement method of MOV(Motor Operated Valve) operability without major modification or change of MOV which needs a great expense and manpower. We studied valve stem lubrication, stem packing thrust and actuator control switch which could give an major effect to MOV operability, and found the some consequences. First, the stem/stem-nut friction coefficient and stem factor is significantly effected by stem lubrication state. Second, the measured packing thrust value is appeared higer than the design value for tested valves and the preparation of optimal value selection criteria is needed. Finally, optimization of MOV control switch is another major factor for MOV operability and structual integrity.

• 제어로봇시스템학회논문지
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• 제12권12호
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• pp.1197-1201
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• 2006

In order to improve the operability in a fully thermally coupled distillation column the main column is separated into an upper and a lower column, and its design method is explained. With a distillation experiment using a two-inch column the operability of the proposed column is examined. Readily available methanol, ethanol and propanol are used as the feed, and the experimental result is compared with that of the HYSYS simulation. It is found from the experiment that the recovery ranges between 58.8% and 68% and the distillation efficiency is lower than that of the simulation. consumes less energy than an original column, it is not widely implemented in practice due to its operational difficulty. However, it is proved that the proposed distillation column can be operated without compressors and it can be practically utilized.

• 한국산학기술학회논문지
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• 제22권2호
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• pp.774-780
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• 2021

회전익 항공기의 보조동력장치(APU, Auxiliary Power Unit)는 지상 운용/비행 중 주 동력 기관의 시동, 환경제어시스템용 고압 공기 공급, 비상발전기 등의 역할을 수행한다. 보조동력장치(이하 'APU')는 소형 가스터빈엔진형태로 구성되어 있으며, 해당 구성품의 시동 원리는 전기 시동 모터를 사용하는 방식으로, 축을 회전시켜 시동에 필요한 동력을 발생시킨다. 본 연구에서는 회전익 항공기에 장착된 APU의 시동 모터 운용성 확보를 위해 APU와 APU 시동 모터 간 축간 분리 장치(Over-Running Clutch) 적용을 통한 품질개선을 수행하였다. APU 시동 모터는 초기 APU 시동이 주 역할이지만, 운용 시 실제 작동 시간 이후에도 APU 기어축의 회전력에 의해 무 부하 회전을 하게 되어 구성품/부품 간 과도한 마찰력이 지속적으로 발생하였다. 이러한 현상은 시동 모터 내부 브러시 마모를 유발하게 되고, 결과적으로 항공기 운용을 위한 APU 작동 시간 증가 시 브러시 운용 수명 감소와 APU의 운용성에 영향을 미치게 된다. 따라서 본 연구에서는 APU 시동 모터의 운용성/내구성 향상을 위하여 시동 모터 브러시 마모와 APU 작동시간의 연동성을 분리하는 축간 분리 장치(Over-Running Clutch)적용하여 시험으로 효과를 검증하였고, 설계변경에 따른 기술적 타당성을 분석하였다.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2022년도 가을 학술논문 발표대회
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• pp.225-226
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• 2022

In order to secure the practicality of services using drones, improve on-site operability, and improve the convenience of aircraft maintenance, it is necessary to develop a drone station that can be safely stored while ensuring charging performance. Therefore, a total seven points of improvement were derived through laboratory experiments after the development of the first prototype, and an improved second prototype will be developed in the future based on the preceding processes.

• Journal of Communications and Networks
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• 제11권6호
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• pp.615-625
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• 2009

Worldwide inter-operability for microwave access (WiMAX) is a promising technology that provides high data throughput with low delays for various user types and modes of operation. While much research had been conducted on physical and MAC layers, little attention has been paid to a comprehensive and efficient security solution for WiMAX. We propose a hybrid security solution combining identity-based cryptography (IBC) and certificate based approaches. We provide detailed message exchange steps in order to achieve a complete security that addresses the various kind of threats identified in previous research. While attaining this goal, efficient fusion of both techniques resulted in a 53% bandwidth improvement compared to the standard's approach, PKMv2. Also, in this hybrid approach, we have clarified the key revocation procedures and key lifetimes. Consequently, to the best of knowledge our approach is the first work that unites the advantages of both techniques for improved security while maintaining the low overhead forWiMAX.

• 제어로봇시스템학회논문지
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• 제5권6호
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• pp.753-763
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• 1999

The existing SCADA(Supervisory Control and Data Acquisition) system software is usually developed to suitable for the specific hardware platforms. However, as per rapid improvement of computer performance and development of network technology, it is required to support scalability and inter-operability in existing different SCADA systems. In order to meet such requirements, in this paper, we propose a new type of SCADA testbed using Java for electric distribution applications. The system consists of three modules; development support tools, client and server modules. The basic architecture of the proposed SCADA system is similar to existing one, however, we improve the function of MTU and MMI interface to facilitate LAN and WAN environment. Also, the proposed system can deals with alarm and history data by using heterogeneous DBMS. Since the system is built in Java environment, the development cost is cheap and it can support sacalability and portability. Our experience can be utilized to develop next generation of small and medium size of SCADA system.

• 한국재난정보학회 논문집
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• 제17권2호
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• pp.391-402
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• 2021

연구목적: 안전인증 생태계 주체별 의견 유형화를 통하여 제도 운영상의 취약점을 확인하고 미래 변동성에 대하여 안전인증제도가 빠른 회복력을 가질 수 있도록 개선방안을 제시하고자 한다. 연구방법: 문헌조사 및 자료 분석을 통해 국내·외 유사 안전인증 및 관련 사례와 국제 기준 및 국가 표준 현황 등을 확인하였으며, 안전인증 생태계의 이해관계자별로 실태조사를 실시하고 문제점 유형화 및 개선방안을 수립하였다. 연구결과: 안전인증대상기계등을 제조 또는 수입하거나 사용하는 사업장을 대상으로 안전인증 대상품에 대한 품질 만족도, 개발제조 및 사용과정에서의 장애요인, 안전인증 관련 개선사항 등 제도전반에 걸친 실태조사를 실시하고 제도 운영상의 문제점 및 취약점을 발굴 및 범주화하여 개선방향 수립 및 작동성 향상을 위한 세부 추진과제를 도출하였다. 결론: 안전인증제도의 선진화·국제화를 위해서는 본 연구를 통하여 도출된 세부 추진과제를 효율적으로 수행하여야 할 것이며, 더불어 안전인증 생태계의 변동성에 대한 회복력 강화를 위해서는 주체별 상호 관계 개선을 통하여 선순환 구조의 운영시스템 구축이 중요하다고 판단된다.

• 한국시뮬레이션학회논문지
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• 제19권4호
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• pp.31-41
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• 2010

지금까지의 함정과 관련된 연구들은 전술 체계 및 함정 개발 위주로 진행되어 왔으며 승조원의 거주 생활 환경 개선에 대한 연구는 부족했다. 본 연구 대상인 함정 crew mess room은 승조원 불특정 다수가 이용하는 함정 내 대표적인 복지 시설물로 기존의 전술 전략 중심의 모델링 및 시뮬레이션 방법론의 적용은 어려움이 있다. 이에 시설물의 혼잡도 평가 및 운용 시나리오 검증을 위한 3차원 이산 사건 시뮬레이션 기반의 시뮬레이션 모델링 프레임워크를 제안하고 구체적인 사례를 통해 대기시간 이동시간, 이동거리 등의 결과 분석을 통해 이를 검증하였다. 제안한 혼잡도 평가 시뮬레이션 프레임워크는 함정 crew mess room과 같은 복지성격의 시설물의 모델링 및 시뮬레이션을 적용하기 위한 절차 및 시스템 구성 요소를 포함하고 있으며 이는 향후 시뮬레이션 연구 수행에 가이드 역할을 수행할 수 있다.

• 대한물리의학회지
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• 제18권4호
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• pp.155-162
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• 2023

PURPOSE: The primary objective of this study was to develop a virtual reality-based vestibular rehabilitation system to enhance balance perception, target rehabilitation specialists, and evaluate its usability. A key goal was establishing a system refinement strategy based on the collected data. METHODS: We conducted a study involving ten adults aged 10 to 29 in Gwangju Metropolitan City to evaluate the usability of a virtual reality-based vestibular rehabilitation system to enhance balance perception. After introducing the product and explaining its use to the participants, balance assessments and training were conducted using computerized dynamic posturography (CDP) (also called the test of balance [TOB]). Subsequently, participants were given a questionnaire to evaluate subjective stability, operability, and satisfaction. Frequency analysis was utilized to determine the frequency of the variable values of the measurement items in the survey for descriptive statistics. RESULTS: We found that the average usability score was 2.587. When broken down by category, stability received an average rating of 2.725, operability scored an average of 2.783, and satisfaction averaged 2.454. These findings suggest that most participants experienced positive sentiments and considerable satisfaction. CONCLUSION: The study successfully developed a virtual reality-based vestibular rehabilitation system, which was an improvement over the previous model and addressed its shortcomings. The results show that users with vestibular impairments are satisfied and more engaged with this system, indicating that additional studies are warranted.