• Management Science and Financial Engineering
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• 제13권1호
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• pp.93-113
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• 2007

In the previous research, we considered a logistics brokerage problem with the objective of minimizing total transportation lead time of freights in a logistics e-marketplace, in which a logistics brokerage agent intermediates empty vehicles and freights registered by car owners and shippers [7]. However, in the logistics e-marketplace, transportation due date tardiness is more important than the transportation lead time, since transportation service level is critically determined by whether the due date is met or not. Therefore, in this paper, we deal with the logistics brokerage problem with the objective of minimizing total tardiness of freights. Hungarian method based matching algorithms, real time matching(RTM), periodic matching(PM), and fixed matching(FM), are used for solving the problem considered in this paper. In order to test performance of the proposed algorithms, we perform computational experiments on a various problem instances. The results show that the waiting-and-matching algorithms, PM and FM, also give better performance than real time matching strategy, RTM, for the total tardiness minimization problem as the algorithms did for the total lead time minimization problem.

• Communications for Statistical Applications and Methods
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• 제11권2호
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• pp.213-225
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• 2004

A fixed-strike lookback option is an option whose payoff is determined by the maximum (or minimum) price of the underlying asset within the option's life. Under the Black-Scholes framework, the time-t price of an equity asset follows a geometric Brownian motion. Applying the method of Esscher transforms, this paper will derive explicit pricing formulas for fixed-strike lookback call and put options, respectively. In addition, this paper will show a relationship (duality property) between the pricing formulas of the call and put options. Finally, this paper will derive explicit pricing formulas for the fixed-strike lookback options when their underlying asset pays dividends continuously at a rate proportional to its price.

• Journal of Biosystems Engineering
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• 제31권5호
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• pp.416-422
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• 2006

Drying characteristics of green onion and onion during fluidized and fixed bed drying were investigated and compared. Sliced peen onion and onion were dried at drying air temperature of 45, 55, and $65^{\circ}C$. Drying air velocity during fluidized bed drying was adjusted with drying time at each drying temperature. Drying time to reach a given final moisture content was shorten in fluidized bed drying than in fixed bed drying - for drying temperature of 45, 55, and $65^{\circ}C$, the differences were 60, 60, and 50 min for green onion and 360, 180, and 60 min for onion. Drying constant (K) was greatly affected by drying method and drying temperature. Terminal velocity under fluidized bed drying was decreased exponentially for green onion and linearly (or onion with increase of drying temperature. Also, terminal velocity had linear relationship with moisture content for both green onion and onion.

• Structural Engineering and Mechanics
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• 제41권3호
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• pp.365-378
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• 2012

In this study, strength reduction factors are investigated for SDOF systems with period range of 0.1-3.0 s with elastoplastic behavior considering soil structure interaction for 64 different earthquake motions recorded on different site conditions such as rock, stiff soil, soft soil and very soft soil. Soil structure interacting systems are modeled and analyzed with effective period, effective damping and effective ductility values differing from fixed-base case. For inelastic time history analyses, Newmark method for step by step time integration was adapted in an in-house computer program. Results are compared with those calculated for fixed-base case. A new equation is proposed for strength reduction factor of interacting system as a function of structural period of system (T), ductility ratio (${\mu}$) and period lengthening ratio (T/T). It is concluded that soil structure interaction reduces the strength reduction factors for soft soils, therefore, using the fixed-base strength reduction factors for interacting systems lead to non-conservative design forces.

• 한국산학기술학회논문지
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• 제9권6호
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• pp.1592-1598
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• 2008

기존의 교통신호기의 방법은 고정신호제어기이다. 즉, 교통대안을 한 가지씩 채택하여 24시간 내내 이미 결정한 교통신호대안에 의존하여 주기 싸이클을 결정하는 방법이다. 교통신호 운영자가 교통대안을 잘못 입력하여 설정하게 되면 교차로내에서 잘못된 교통대안으로 인해 교통지체가 빈번하게 일어남을 알 수 있다. 교통대안은 눈으로 보아 설정하는 것이 아니고 유력한 교통대안을 서로 비교하여 가장 영향력 있는 교통대안을 설정하는 것이 교통신호제어에 유효하다. 본 논문에서는 고정신호제어기를 사용하여 제어기에 맞는 교통대안을 찾는 방법을 퍼지계층분석방법을 이용하여 찾는 방법을 모색하고 기존제어기와 비교 검토한다.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 1999년도 추계종합학술대회 논문집
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• pp.1131-1134
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• 1999

In general CELP type vocoders provide good speech quality around 4.8kbps. Among them, G.723.1 developed for Internet Phone and videoconferencing includes two vocoders, 5.3kbps ACELP and 6.3kbps MO-MLQ. Since 6.3kbps MP-MLQ requires large amount of computation for fixed codebook search, it is difficult to realize real time processing. In order to improve the problem this paper proposes the new method that reduces the processing time up to about 50% of codebook search time. We first decide the grid bit, then search the codebook. Grid bit is selected by comparison between synthetic speech, which is synthesized with only odd or even pulses of target vector. and DC removed original speech. As a result, we reduced the total processing time of G.723.1 MP-MLQ up to about 26.08%. In objective quality test 11.19㏈ of segSNR was obtained, and in subjective quality test there was almost no speech degradation.

• Structural Engineering and Mechanics
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• 제44권4호
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• pp.521-538
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• 2012

In this study, the transverse vibrations of an axially moving flexible beams resting on multiple supports are investigated. The time-dependent velocity is assumed to vary harmonically about a constant mean velocity. Simple-simple, fixed-fixed, simple-simple-simple and fixed-simple-fixed boundary conditions are considered. The equation of motion becomes independent from geometry and material properties and boundary conditions, since equation is expressed in terms of dimensionless quantities. Then the equation is obtained by assuming small flexural rigidity. For this case, the fourth order spatial derivative multiplies a small parameter; the mathematical model converts to a boundary layer type of problem. Perturbation techniques (The Method of Multiple Scales and The Method of Matched Asymptotic Expansions) are applied to the equation of motion to obtain approximate analytical solutions. Outer expansion solution is obtained by using MMS (The Method of Multiple Scales) and it is observed that this solution does not satisfy the boundary conditions for moment and incline. In order to eliminate this problem, inner solutions are obtained by employing a second expansion near the both ends of the flexible beam. Then the outer and the inner expansion solutions are combined to obtain composite solution which approximately satisfying all the boundary conditions. Effects of axial speed and flexural rigidity on first and second natural frequency of system are investigated. And obtained results are compared with older studies.

• 한국음향학회지
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• 제38권5호
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• pp.494-510
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• 2019

수중음향통신시스템의 모뎀이나 채널 코딩 설계를 위한 채널 매개변수는 임펄스 응답, 지연 확산, 산란함수, 도플러 확산, 상관 대역폭, 주파수 선택적 페이딩, 상관 시간 및 시변 진폭 페이딩의 통계적 분포 함수 등이다. 이들 매개 변수들은 주어진 해양 음향 조건에서 수층의 음속 구조, 플렛폼의 운동이나 해면의 거칠기에 영향을 받는다. 본 논문에서는 송수신기 고정 천해 수중음향통신 채널에 대한 페이저 기반의 채널 모델과 모의실험 및 채널 매개변수들의 측정과 분석 방법을 제시하고 천해의 실험 자료를 이용하여 이들 매개변수들을 해석하였다. 송수신기 거리가 300 m와 600 m에 대한 이들 매개 변수들은 직접파, 산란 성분을 갖는 해면 반사파 및 해저 반사파로 구성되는 3개 다중 경로에 의해 그 특징이 결정됨을 보인다. 연구의 결과는 천해 고정 시스템의 채널 모델 방법, 채널 매개변수들의 측정과 분석 방법 및 시스템 설계와 성능평가 방법을 제시한다.

• Journal of Microbiology and Biotechnology
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• 제11권1호
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• pp.35-39
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• 2001

A simple method for studying the lectin-like interactions between Helicobacter pylori and cultured human epithelial cell lines was developed using an enzyme-linked, biotin-streptavidin bacterial-adhesion assay. The present study suggests that this method is suitable for evaluating the participation of lectin interactions in the adhesion of H. pylori to cultured HeLa S3 and Kato III cells, both fixed and glycosidase-treated cells, as well as assessing glycoconjugated binding inhibition studies. The time-course and dose-dependent kinetics of the biotin-labeled H. pylori adhesion th the formaldehyde-fixed Hela S3 and Kato III cell lines exhibited saturation. In addition, the binding of the biotin-labeled H. pylori to the formaldehyde-fixed cultured cells was partially blocked by pre-incubation with glycoconjugates and polyclonal antibodies against a heparan sulfate binding protein from H. pylori.

• 한국군사과학기술학회지
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• 제22권5호
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• pp.590-598
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• 2019

Aerial photographs taken by an image sensor fixed on a flight body, e.g. without a gimbal, are generally distorted according to its attitude, altitude and angle of view in flight. This can result in a significant difficulty of analyzing geometric information which should be integrated for numerous still frames. In this study, a simulation method of observation performance that uses geometric relationships between navigation data and image data is suggested, and this method is shown to be very useful for easily examining the integrated information such as the total range of photography, the time of target acquisition, etc.