• 전력전자학회:학술대회논문집
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• 전력전자학회 2004년도 전력전자학술대회 논문집(1)
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• pp.155-158
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• 2004

This paper describes a lane following control of vision based mobile robot that follows guidline. Summation of binarization conversion and image data of vertical axis was used in image processing. As an extraction of specific parameters of lane image, the raw image was converted to the binary data, and the binary data was summerized to the specific data vertically. The specific parameters were made to the inputs of neural network. Summation of image data was used for input of the net, and optimized value of turn angles of learned mobile robot was output. By using neural network algorithm, possibility of mobile robot moving to the target point and following the guidlines quickly and effectively was proved.

• 대한안전경영과학회지
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• 제10권3호
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• pp.227-235
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• 2008

Recently, as change in global logistics environment, various issues have been presenting. These issues are including the pursuit of low cost-high added value, the realization of sustainable logistics system, the protection of environment, and the development of ubiquitous techniques. To cope with these environment changes and improve the national logistics system, the government have carried out various logistics policies and pushed ahead development of national logistics information network. But still, from a view-point of national logistics, there are several inefficient elements such as information connection and utilization, code/data standardization. In this paper, the survey result of global logistics environment change, logistics policy of a developed countries, domestic logistics policy and information system status will be presented. And from these status, suggestive points are mentioned. Finally the status of railway logistics information and future developments are presented.

• Nuclear Engineering and Technology
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• 제41권8호
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• pp.1115-1126
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• 2009

As one of the ways to enhance the economical features in sodium-cooled fast reactor development, the concept of an integrated steam generator and pump system (ISGPS) is proposed from a structural point of view. And the related intermediate heat transfer system (IHTS) piping layout compatible with the ISGPS is described in detail. To assure the creep design lifetime of 60 years, the structural integrity is investigated through high temperature structural evaluation procedures by the SIE ASME-NH computer code, which implements the ASME-NH design rules. From the results of this study, it is found that the proposed ISGPS concept is feasible and applicable to a commercial SFR design.

• 수산경영론집
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• 제9권1호
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• pp.1-27
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• 1978

The paper attempts to analize the economic situations of the coastal fishing business contering on the fishery right fisheries. Fisheries in Korea are usally divided in to three categories according to the distance fishing grounds; namely, coastal fisheries, off -shore fisheries and deep-sea fisheries. The fishery right fisheries fall into the category of the coastal fisheries, and include five typs of fisheries: 1. Class 1 common fishing 2. Class 2 common fishing 3. Class 3 common fishing. 4. Set-net fishing. 5. Aquarculture fishing. These fisheries have been stagnated mainly due to traditional fishing methods, unskilled labor forces, shortage of capital, and lack of the technological improvements. Owing to these factors their profitabilities of the fishing businesses have been steadly lowered. The main purpose of this paper is to point out the measures required in developing the fishery right fisheries. Economic performances were estimated for 1976 with data collected in the late 1977.

• 대한전자공학회논문지TC
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• 제44권8호
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• pp.62-67
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• 2007

센서네트워크 중에는 센서노드들이 넓은 지역에 걸쳐 정해진 위치에 산재되어야 하는 경우가 있다. 이런 경우 센서노드들을 interconnect하기 위한 최소개수의 연결노드들을 추가하는 문제가 대두되며, 이는 The Minimum number of Steiner Points라는 추상화된 문제로 귀결된다. 이 문제는 NP-hard 문제이므로, 본 논문에서는 문제가 내포하는 기하학적인 성질을 이용하여 연결노드의 최소개수에 근접하는 방안을 제시한다. 센서네트워크에서 노드의 개수를 줄임으로써 네트워크 내부에서 오가는 메시지의 교환량이 대폭 감소하게 된다.

• Nuclear Engineering and Technology
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• 제52권3호
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• pp.477-484
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• 2020

The control rod drive mechanism needs to be debugged after reactor fresh fuel loading. It is of great importance to monitor the subcriticality of this process accurately. A modified method was applied to the subcriticality monitoring process, in which only a single control rod cluster was fully withdrawn from the core. In order to correct the error in the results obtained by Neutron Source Multiplication Method, which is based on one point reactor model, Monte Carlo neutron transport code was employed to calculate the fission neutron distribution, the iterated fission probability and the neutron flux in the neutron detector. This article analyzed the effect of a coarse mesh and a fine mesh to tally fission neutron distributions, the iterated fission probability distributions and to calculate correction factors. The subcriticality before and after modification is compared with the subcriticality calculated by MCNP code. The modified results turn out to be closer to calculation. It's feasible to implement the modified NSM method in large local reactivity addition process using Monte Carlo code based on 3D model.

• Nuclear Engineering and Technology
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• 제52권3호
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• pp.552-559
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• 2020

This paper presents an observer-based chattering free robust optimal control scheme to regulate the total power of a nuclear reactor. The non-linear model of nuclear reactor is linearized around a steady state operating point to obtain a linear model for which an optimal second order integral sliding mode controller is designed. A second order integral sliding mode observer is also designed to estimate the unmeasurable states. In order to avoid the chattering effect, the discontinuous input of both observer and controller are designed using the super-twisting algorithm. The proposed controller is realized by combining an optimal linear tracking controller with a second order integral sliding mode controller to ensure minimum control effort and robustness of the closed-loop system in the presence of uncertainties. The condition for the selection of gains of discontinuous control based on the super-twisting algorithm is derived using a strict Lyapunov function. Performance of the proposed observer based control scheme is demonstrated through non-linear simulation studies.

• KDI Journal of Economic Policy
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• 제38권4호
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• pp.1-21
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• 2016

This paper documents how the net profit margin of private firms improves when the CEOs of the companies relocate their primary residence to be closer to the corporate headquarters. By reviewing 127 Korean non-public companies belonging to 66 private business groups, we find that the top managers move closer to the headquarters when the profitability of the firms has recently deteriorated. A one basis point decline in the margin causes CEOs to relocate their homes approximately two kilometers closer to their corporate headquarters. The profit margin rebounds after their relocation. This finding implies that physical proximity can serve as a proxy for personal commitment.

• 대한기계학회논문집
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• 제18권9호
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• pp.2413-2422
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• 1994

The effects of compressor design conditions on the off-design performance of a single-shaft gas turbine engine have been studied. Three different geometric design conditions are considered and three different values for the specific mass flow rate at the inlet to the compressor are assumed. For each of nine compressor design, the off-design performance of the gas turbine engine is predicted using the method previously proposed by present authors. Results show that the predicted off-design performances are quite different from each other even though they have the same performance at design point: it means that compressor design conditions should be determined in consideration of the off-design performance of the engine. The specific mass flow rate at the inlet to the compressor is also shown that it might be optimized with respect to the net power of the engine.

• 대한기계학회논문집
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• 제18권4호
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• pp.946-957
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• 1994

In the steel industries, direct rolling process for production of strip from molten metal has been investigated to simplify processes, to minimize energy consumption, and to improve quality of the strip. In this study, two kinds of practicable scale cooling rollers are proposed. And heat transfer analysis of pool region and cooling roller considering flow of molten metal and roll rotation respectively using the finite element method are performed to obtain the proper initial condition and to observe cooling characteristics of cooling roller. From the results, variations of solidification final points and temperature distribution in roller are observed quantitatively according to roll rotation.