• 한국소음진동공학회논문집
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• 제12권1호
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• pp.12-20
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• 2002

To control the noise of an enclosed sound field, we built a state space model using the acoustic modal parameter description. Using the state space model, we can investigate the controllability and observability, and find an appropriate position of control speaker and microphone to control sound field of the enclosed space. We implemented LQR(linear quadratic regulator) controller and reduced order observer to reduce the first acoustic mode. Experiments showed satisfactory results of 4∼10 dB reduction of magnitude of the first acoustic mode, and support the feasibility of the proposed scheme to lightly damped acoustic field.

• Journal of Advanced Marine Engineering and Technology
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• 제28권5호
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• pp.837-846
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• 2004

This paper presents a screening technique for greatly reducing the computation involved in determining the optimal location and types of Flexible AC Transmission System (FACTS) devices in a large power system. The first-order sensitivities of the generation cost for various FACTS devices are derived. This technique requires solving only one optimal power flow (OPF) to obtain sensitivities with respect to FACTS device control variables for every transmission line To implement a sensitivity-based screening technique, we used a new UPFC model, which consists of an ideal transformer with a complex turns ratio and a variable shunt admittance. A S-bus system based on the IEEE 14-bus system was used to illustrate the technique.

• Journal of the Korean Physical Society
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• 제73권11호
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• pp.1631-1636
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• 2018

Unpolarized 1.047-GeV proton inelastic scatterings from the Ni isotopes $^{62}Ni$ and $^{64}Ni$ are analyzed phenomenologically employing an optical potential model and the first-order collective model in the relativistic Dirac coupled channel formalism. The Dirac equations are reduced to $Schr{\ddot{o}}dinger-like$ second-order differential equations, and the effective central and spin-orbit optical potentials are analyzed by considering the mass-number dependence. The multistep excitation via the $2^+$ state is found to be important for the $4^+$ state excitation in the ground state rotational band for proton inelastic scatterings from the Ni isotopes. The calculated deformation parameters for the $2^+$ and the $4^+$ states of the ground state rotational band and for the first $3^-$ state are found to agree pretty well with those obtained from nonrelativistic calculations.

• 전기전자학회논문지
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• 제25권2호
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• pp.261-266
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• 2021

이 논문에서는 환경 온도 변화를 고려한 열 적외선 데이터 보정 알고리즘을 설계하는 방법을 제시한다. 첫째, 열 적외선 측정 모델은 적외선 측정 데이터와 모델 환경 매개 변수 간의 관계를 사용하여 매개 변수 종속적인 1차 입력-출력 방정식으로 주어지고, 적외선 데이터에 대한 환경 온도의 영향을 보상하기 위해 보상 함수를 구한다. 실험을 통해 제안된 알고리즘이 적외선 데이터에 대한 환경 온도 변화의 영향을 효과적으로 보상할 수 있음을 보인다.

• 한국경영과학회지
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• 제11권1호
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• pp.44-50
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• 1986

In this paper, we find optimal policy for the (Q, r) inventory model under the lead time uncertainty. The (Q, r) inventory model is such that the fixed order quantity Q is placed whenever the level of on hand stock reaches the reorder point r. We first develop the single level inventory model as the basis for the analysis multi-level distribution systems. The functional problem is to determine when and how much to order in order to minimize the expected total cost per unit time, which includes the set up, inventory holding and inventory shortage cost. The model, then, is extended to the multi-level distribution system consisting of the factory, warehouses and retailers. In this case, we also find an optimal policy which minimizes the total cost of the contralized multi-level distribution system.

• STI Policy Review
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• 제1권1호
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• pp.93-109
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• 2010

Over the last decade, some Korean enterprises have emerged to become global players in their specialized products. How have they achieved such tremendous technological progress in a short period of time? This paper explores that question by examining the characteristics of technological innovation activities at major Korean enterprises. The paper begins with a brief review of the stages of economic growth and science and technology development in Korea. Then, the existing literature, explaining the Korean innovation model, is analyzed in order to establish a new framework for the Korean innovation model. Specifically, Korean firms have experienced three sequential phases, and thus, the Korean model, at the firm level, can be coined as "path-following," "path-revealing," and "path-creating." Then, the stylized facts in the first phase (path-following) and the second phase (path-revealing) are discussed, in the context of empirical evidence from the areas of memory chips, automobiles, shipbuilding, and steel. In terms of technology development, the Korean model has evolved as "collective learning" in the first phase, "collective recombination" of existing knowledge and technology in the second phase, and is assumed as "collective creativity" in the third phase. Ultimately, all three can be classified as "collective creation". Korean firms now face a transition in the modes of technological innovation in order to efficiently implement the third phase. To achieve remarkable progress again, as they did in the past, and to sustain the growth momentum, Korean firms should challenge new dimensions such as creative technological ideas, distinctive technological capabilities, and unique innovation systems -- all of which connote 'uniqueness'. Finally, some lessons from the Korean technological innovation experience are addressed.

• 전자공학회논문지B
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• 제29B권11호
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• pp.16-21
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• 1992

The validity of the application of the second-order Born equation to the ultrasound tomography algorithm is studied by comparing the scattered fields computed using the first-order Born equation, the first-order Rytove equation, and the second-order Born equation. The second-order Born equation turns out to provide more desirable results than the other two equations for a certain group of test objects. Phantom images with resolutions upto 1 pixel$\times$1 pixel are satisfactorily reconstructed using the second-order Born equation. It is shown that when the view angle is limited, good resonstruction results are also obtained using multi-frequency incident fields.

• 한국경영과학회:학술대회논문집
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• 한국경영과학회 2007년도 추계학술대회 및 정기총회
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• pp.358-373
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• 2007

In this paper, we proposed the next generation mobile convergence service business model creation methodology. In order to establish such a business model creation methodology framework, we first introduce the service model based on our previous research results on next generation mobile convergence services. The service model contains several components such as infrastructures, operations, and provision of services that are indispensible for providing the next generation mobile services. Finally, by adding service and value flows to the developed service model, we propose the next generation mobile services business model creation methodology. To achieve this objective, we first derive necessary components of business model including actors, their relationships, and roles. In addition, we propose service composition methodology for creating new mobile services and its corresponding business models.

• 생태와환경
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• 제36권3호통권104호
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• pp.295-303
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• 2003

자연습지 토양에서 소수성 유기화합물(염화벤젠 및 페난쓰린)의 흡착동력학을 실험실규모의 회분식 반응기를 이용하여 조사하였다. 단일영역 물질전달모델 (one-site mass transfer model, OSMTM)과 두영역 1차속도모델 (two compartment first-order kinetic model, TCFOKM)을 사용하여 흡착속도를 분석하였다. OSMTM 분석결과 염화벤젠의 경우 10${\sim}$75시간 이내에, 페난쓰린의 경우 약 2시간 이내에 각각 겉보기 흡착평형에 도달하였다. 염화벤젠의 경우, 표면 토양에서의 흡착평형시간이 하부 토양보다 길게 나타났는데, 이는 토양 유기탄소의 물리화학적 특성의 차이에 기인한다. 그러나, 페난쓰린의 경우 각 토양간에 흡착평형시간의 차이는 없었다. 관련 모델매개변수의 수에서 기대되듯이 변수가 3개인 TCFOKM이 변수가 2개인 OSMTM보다 흡착속도를 더 잘 표현할 수 있었다. 실험결과에 대한 TCFOKM의 곡선맞춤으로부터 얻은 매개변수인 빠른 흡착영역의 분율($f_1$)과 빠른 흡착영역과 느린 흡착영역의 1차 흡착속도 상수($k_1$,및 $k_2$)를 얻을 수 있었다. TCFOKM 분석결과 빠른 흡착영역에서의 흡착속도 상수는 느린 흡착영역에서의 흡착속도 상수 보다 큰 것으로 나타났다. 빠른 흡착영역의 분율 ($f_1$)과 흡착속도상수 ($k_1$)는 $k_{ow}$ 값이 증가(페난쓰린>염화벤젠)함에 따라 증가하였다. 빠른 흡착영역과 느린 흡착영역에서의 1차 흡착 속도상수는 각각$10^{-0.1}\;-10^{+1}$과 $10^{-4}\;-10^{-2}$의 범위에서 변화하였다.

• 경영과학
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• 제21권3호
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• pp.101-113
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• 2004

In the rapidly propagating Internet based electronic transaction environment. the importance of real time order confirmation has been more emphasized, In this paper, using data mining techniques, we develop intelligent operations decision model to allow real time order confirmation at the time the customer places an order with required delivery terms. Among various operation plannings used for order fulfillment. mill routing is the first interface decision point to link the order receiving at the marketing with the production planning for order fulfillment. Though linear programming based mathematical optimization techniques are mostly used for mill routing problems, some early orders should wait until sufficient orders are gathered for optimization. And that could effect longer order fulfillment lead-time, and prevent instant order confirmation of delivery terms. To cope with this problem, we provide the intelligent decision model to allow instant order based mill routing decisions. Data mining techniques of decision trees and neural networks. which are more popular in marketing and financial applications, are used to develop the model. Through diverse computational trials with the industrial data from the steel company. we have reported that the performance of the proposed approach is effective compared to the present heuristic only mill routing results. Various issues of data mining techniques application to the mill routing problems having linear programming characteristics are also discussed.