• Journal of the Korea Computer Industry Society
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• 제2권7호
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• pp.967-974
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• 2001

This paper aims at deriving an equivalent finite dimensional discrete-time system for $H{\infty}$ type problem for sampled-data control systems. A widely used approach is based on the lifting technique, but it needs somewhat complicate computation. Instead, this paper derives an equivalent finite-dimensional discrete-time system directly from a description of the sampled-data system which is achieved via a closed-loop expression of the worst-case intersample disturbance.

• The KIPS Transactions:PartC
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• 제13C권2호
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• pp.167-170
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• 2006

Most wavelength assignment algorithms assume that every node has infinite ADMs and I/O blocking is excluded. Furthermore wavelengths continue to occur intermittently in the network using existing algorithms. This can result in increased link blocking under dynamic traffic circumstances. In audition, it can create time-complexity problems such as O(W $N^3$) in the worst case scenario. In this paper, we propose a new wavelength assignment algorithm which has time-complexity of O(W $N^2$) and considers both I/O and link blocking. The basic idea is to maximize the number of links where wavelengths will be assigned continuously after present assignment. As a result, the number of intermittent wavelengths is minimized, and blocking probabilities are decreased.

• Proceedings of the Korea Air Pollution Research Association Conference
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• 한국대기환경학회 2003년도 추계학술대회 논문집
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• pp.193-194
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• 2003

'90년대부터 3, 4월 봄철에 부는 황사현상은 해마다 발생량이 증가되는 것은 물론 그 시기 또한 빨라지며 최근 들어는 계절과 관련 없이 가을과 겨울황사도 발생되고 있음을 볼 수 있다. 다행이 올해의 경우는 지난 2002년 겨울 황사발생지의 강수량 증가로 인하여 다소 소강상태를 보이고 있으나 지난해 3월과 4월 최악의 황사대란을 맞이하였던 우리 나라의 경우는 단순한 월경성 대기오염을 넘어서 2002년 4월에는 황사예보제가 실시되고 있는 실정이다. (중략)

• Proceedings of the Korean Information Science Society Conference
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• 한국정보과학회 2004년도 가을 학술발표논문집 Vol.31 No.2 (1)
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• pp.511-513
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• 2004

MMF(Memory Mapped File)는 대응된 주소 영역을 접근함으로써 파일에 대한 입.출력 효과를 얻는 기본적인 활용 외에, 커널 영역에 버퍼를 설정하여 입.출력 성능을 향상시키거나 파일의 효율적인 공유를 위한 수단 등 다양한 방법으로 사용된다. 기본 기능 활용의 대표적인 예 중의 하나가 웹 파일 서비스이다. 이 논문에서는 웹 서비스 성능향상을 위한 연구의 일환으로 몇 가지 유닉스/리눅스 시스템을 대상으로 MMF의 기본 기능에 대한 성능을 비교.분석하였다 그 결과 시스템 별로 상당한 차이가 있다는 사실이 드러났으며, 최악의 경우에는 오히려 성능이 30% 이상 저하되는 경우가 발견되었다.

• Fire Science and Engineering
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• 제33권4호
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• pp.112-120
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• 2019

Benzene is a class 4 hazardous material according to the Act on the Safety Control of Hazardous Substances. This study qualitatively evaluated the damage size of a "toxic" accident and "pool fire" accidents based on benzene in a virtual scenario of a fire and leakage accident during unloading at a port facility. The KORA program was used as an evaluation method, which is supported as a universal program by the National Institute of Chemical Safety. The range of damage effects of a benzene-induced fire and leakage accident was predicted. In the case of toxic damage range, the accident's damage effect range for the "worst case scenario" was reduced by up to 5.11% with a decrease in the size of the leakage hole. In the case of the leakage time, the damage effect range increased to 145.12% with a 10 min leakage time compared to that of a 5 min leakage time and went up to 20 min (212.29%) with a 20 min leakage time. In the case of pool-fire-induced damage, the damage effect range by radiant heat in the "worst case scenario" was 228.8 m in radius from the center of the handling facility. In the "alternative scenario," the damage effect range by radiant heat was reduced by up to 8.26% compared to that in the "worst case scenario" since the size of the leakage hole was decreased by reducing the cross-sectional area of the pipe.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• 제18권10호
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• pp.1196-1202
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• 2007

In this paper, the effects of performance improvement far the OFDM based satellite communications are analyzed with applying the CI(Carrier Interferometry)-OFDM and channel coding scheme considering the group delay and gain ripple characteristic as well as the nonlinear characteristic of the transponder. Comparing the BER between traditional OFDM and CI-OFDM, the degree of performance improvement is presented in AWGN channel environments for specified backoff condition of HPA. The simulations are performed with the 36 MHz bandwidth of transponder channel, 120 Mbps transmission rate, and 16 QAM modulation scheme between ideal and worst case condition. It is shown that the improvement measure by the CI-OFDM and channel coding for the group delay and nonlinear characteristic outperforms that for the gain ripple in terms of performance degradation presented by the individual characteristics. And the simulation results show that the effects of improvement by the CI-OFDM outperforms the effect by the applied channel coding, particularly in worst case condition.

• Journal of Korean Society of Environmental Engineers
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• 제36권9호
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• pp.629-640
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• 2014

In this study, the applicability of dynamic water quality model to TMDL system was examined, methods for setting of water quality goal and estimation of allocation loads were suggested and results of applying these methods were analyzed. HSPF model was applied for Miho stream basin as a dynamic water quality model. The model was calibrated using measurement data obtained in 2009~2010 and showed satisfactory performance in predicting daily variations of flow rate and BOD concentration. Methods for TMDL application were categorized into 3 cases; water quality management (1) considering low flow condition(Case I), (2) considering entire period of the year (Case II) and (3) considering the worst water quality condition (Case III). BOD water quality goals at the end of Miho stream watershed increased in the order of Case IICase I>Case III. If further researches on base precipitation and method for model input of nonpoint source pollutant were carried out, water quality could be managed more reasonably and scientifically by applying dynamic water quality model to TMDL. The result of this study is expected to be used as primary data for TMDL using dynamic water quality model.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 한국소음진동공학회 2001년도 추계학술대회논문집 I
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• pp.419-426
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• 2001

Industrial products determined by fixed size posses definite limits variety by manufacture tolerance in existence. The optimum value solved by deterministic approaches do not account of tolerance bands of design variables and material properties. If we examine optimum value considering tolerance bands of design variables and material properties, it might be useless, owing to exist infeasible region. We have two ways to prevent being useless value. The one is to minimize tolerance band, the other is to consider tolerance band in optimum design. The former needed more accuracy during manufacturing process require higher production cost, the letter is more appropriate to consider tolerance band. In this research, we consider the tolerance bands of all variables, which might have the tolerance bands used in the problem, based on optimum value of deterministic approaches. Orthogonal arrays are used to minimize the number of trial. Tolerance bands are supposed discretionary according to design variable. Appropriateness suggested by this research is examined through two examples. Mathematical problem is investigated only in terms of tolerance bands of design variables, and cantilever beam problem is explained through tolerance bands of design variable, material properties and loading conditions. It is proved that values from the presented method are satisfactory for tolerance bands of variables.

• Journal of the KSME
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• 제17권3호
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• pp.168-174
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• 1977

과학기술의 비약적인 발전에 따라서, 우주개발, 해양개발등을 실현시키는 단계에 이르렀고, 또한 이에 발맞추어 기계 및 구조물에 사용되는 각종부재의 경량화를 꾀하는 한편 사용장소가 매우 험악해지고 있다. 이와같은 사회적인 추세에 따라 재료가 보다 협악한 조건화에서 사용된다는 사 실은 최근에는 일만상식처럼되고 있다 따라서 험악한 장소에서 파괴가 발생한다면 최악이 경우는 인명을 위협하기도 한다. 이와같은 일반사항을 고려하여 본강좌(4) 에서는 특히 부식되기쉬운 장 소에서 부재가 사용되었을 때의 부식피로에 대하여, 극히 일반적인 사항을 간추려보기로 하겠다.

• Proceedings of the Korean Society for Quality Management Conference
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• 한국품질경영학회 2004년도 품질경영모델을 통한 가치 창출
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• pp.133-141
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• 2004

최근 국내 중소 제조 기업들은 최악의 상황을 맞이하고 있다. 내수부진으로 인한 국내 경기 불황에다 지난 해 말부터 불어닥친 국제 원자재 가격폭등까지 겹치면서 경영 상황이 악화되고 있는 것이다. 더욱이 부풀이나 부자재를 생산하여 모기업에 납품하는 형태의 중소 제조공급자 기업의 경우에는 그 어느 때보다도 치열한 전쟁과 같은 상황에 직면하여 사투를 벌이고 있는 것이다. 이러한 변화무쌍한 시대에 우리의 중소 제조공급자 기업의 특성을 재조명 해보고, 선행연구의 검토를 통해 경영혁신의 성공요인과 경영성과 및 경쟁력 향상 방안에 대해 고찰해 보고자 한다.