• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.5
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• pp.77-83
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• 2020

4WD technology is being actively applied to passenger cars. Therefore, dry multi-plate clutches are used for transfer cases. On the other hand, dry clutches have problems related to large vibrations and poor ride quality. To solve this problem, this paper proposes a multi-plate clutch with an MR fluid. When fastening the multi-plate clutch in the transfer case, the proposed MR clutch was applied to reduce the shock and friction, which is a key component in a four-wheel-drive system. MR multi-plate clutch has a fluid coupling mode and a compression mode. A torque model equation was derived for the optimal design. The analysis was performed using Ansys Maxwell to optimize the design parameters of the multi-plate clutch. Electromagnetic field analysis confirmed the strength of the magnetic field when the number of disks and plates were changed, and the maximum strength of the magnetic field was 0.45 Tesla. By applying this to the torque equation, the spacing between the plates was 2 mm, and the inner and outer diameters of the plates were selected to be 45 mm and 55 mm, respectively. Overall, this paper proposes an optimal design technique to maximize the performance of an MR multi-plate clutch.

• The Journal of the Petrological Society of Korea
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• v.24 no.2
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• pp.77-90
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• 2015

The fission track registration techniques for accurate determinations of uranium in solid- and liquid-state geological materials were recommended and their applicability were examined. The determination of uranium can be achieved by optical counting of neutron-induced fission tracks of $^{235}U$ registered on solid-state track detectors under high magnification. In a dry registration method using powdered pellets of rocks (e.g., granite and coal) showing good uranium-affinity, it was not easy to decide an overall mean concentration over the total sample owing to track-clusters caused by frequent presence of uranium-bearing minerals. Separate scanning for homogeneous and track-clustered parts may be an alternative choice. Assuring the homogeneity over the whole sample, high reproducibilities were confirmed both from duplicate detections using mica and Lexan polycarbonate detectors and from multiple measurements at different thermal neutron fluences. The wet registration method using sealed quartz tubes is recommended to overcome the common heterogeneity in uranium concentrations of $10^1ppm$ and more. Adopting the wet registration, the uranium homogeneity was recovered below the $10^0ppm$ level and the lower detection limit was proved to reach without difficulty the $10^2ppb$ (i.e. $ng\;g^{-1}$) level.

• Journal of Korean Society of Steel Construction
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• v.10 no.4 s.37
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• pp.657-666
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• 1998

This study presents an effective dual algorithm for the optimal design of steel structures with displacement constraints. The dual method can replace a primary optimization problem with a sequence of approximate explicit subproblems with a simple algebraic structure. Since being convex and separable, each subproblem can be solved efficiently by the dual method. Specifically, this study uses the principle of virtual work to obtain the displacement constraint equations with an explicit form and adds the linear regression equation expressing the relationships between the cross-section properties to the dual algorithm to reduce the number of design variables. Furthermore, this study deals with the discrete optimization problem to select members with the standard steel sections. Through numerical analyses, the proposed method will be compared with the conventional optimality criteria method.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.4 no.3
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• pp.595-602
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• 2000

This paper is aimed at developing an location tracking system of mobile station based on currently available mobile communication network or mobile Phone and PCS(Personal Communication System). When the location tracking of mobile stations is in services, Emergency-119, all of crime investigation, effective urban traffic management and the safety protection of Alzheimer＇s patients can be available. In order to track the location of the mobile and base station, assumption in this paper is to use the statistic characteristics of LOS when modeling the standard noise in case that radio path is LNOS environment. The standard variation of the standard noise is $\pm150$. First, location is estimated by the positioning algorithms of TOA and TDOA and compared each other. Second, after canceling the standard noise by Kalman filter, location is estimated by the above two positioning algorithms. Finally, the location by the Kalman filter and two positioning algorithms is estimated by smoothing method. As a result, 2 dimensional average location error is imvoved by 51.2m in TOA and 34.8m in TDOA when Kalman filer and two positioning algorithms are used, compared with the two positioning algorithm used. And there is 3 more meter improvement after smoothing than Kalman filer and two positioning algorithms used.

• Journal of Korean Society of Environmental Engineers
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• v.29 no.1
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• pp.47-53
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• 2007

The aim of this study is to research applicable possibility or Dry Sorbent Injection Technique(DSI) in sox removal process using Computational Fluid Dynamics(CFD) software package. It will be applied for 500MW in capacity coal-fired thermal power plant operated by South Korea N. Power Co., Ltd. The DSI process is adapted between a preheater and an EP process in the technological assembly. The numerical analysis performs in predicting and optimizing of DSI process's characteristics, which consists of structure of duct, position of injection nozzles, injection speed, and dispersion of sorbent. Computing results are shown that degree of sorbent dispersion depends on structure of duct and position of injection nozzles strongly. The highest dispersion efficiency was obtained when we set a Lobed-plate inside the duct and 6 injection nozzles on the duct(4 injection nozzles at the corners and 2 injection nozzles on upper and under walls as a rectangle duct shape). We also know that change of injection speed of sorbent doesn't have an large effect on the sorbent dispersion but it can effect to drop pressure.

• The Journal of the Korea Contents Association
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• v.17 no.1
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• pp.351-362
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• 2017

Recently, analysis techniques to extract new meanings using big data analysis and various services using them have been developed. A disaster safety service among such services has been paid attention as the most important service. In this paper, we design and implement a flood disaster safety system using real time weather big data. The proposed system retrieves and processes vast amounts of information being collected in real time. In addition, it analyzes risk factors by aggregating the collected real time and past data and then provides users with prediction information. The proposed system also provides users with the risk prediction information by processing real time data such as user messages and news, and by analyzing disaster risk factors such a typhoon and a flood. As a result, users can prepare for potential disaster safety risks through the proposed system.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2000.05a
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• pp.167-172
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• 2000

This paper is aimed at developing an location tracking for mobile station employing currently available mobile communication network of cellular phone and PCS(Personal Communication System). When the location tracking of mobile stations is in services, the services such as Emergency-119, crime investigation, effective urban traffic management or the safety protection of Alzheimer's patients, ran be available. This paper is to track the mobile station in communication network in NLOS environment. To achieve reduction of the standard noise, Kalman filter is used. In terms of the distance, positions are located by using TOA and TDOA methods in the environment that removes NLOS bias in the measured data. And then smoothing method is used. to achieve reduction of the position error values

• Proceedings of the Korean Vacuum Society Conference
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• 2011.08a
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• pp.301-301
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• 2011

최근 고밀도 메모리 반도체의 재료와 빠른 응답을 요구하는 나노입자를 이용한 비휘발성 메모리 소자의 제작에 대한 연구가 활발히 진행되고 있다. 그에 따른 기존의 플래쉬 메모리가 가지는 문제점을 개선하기 위해서 균일하고 규칙적으로 분포하는 새로운 나노소재의 개발과 비휘발성, 고속 동작, 고집적도, 저전력 소자의 공정기술이 요구되고 있다. 또한 부유게이트에 축적되는 저장되는 전하량을 증가시키기 위한 새로운 소자구조 개발이 필요하다. 한편, 실리 사이드 계열의 나노입자는 금속 나노입자와 달리 현 실리콘 기반의 반도체 공정에서 장점을 가지고 있다. 따라서 본 연구에서는 화합물 중에서 비휘발성 메모리 장치의 전기적 특성을 향상 시킬 수 있는 실리사이드 계열의 바나듐 실리사이드(V3Si) 박막을 열처리 과정을 통하여 수 nm 크기의 나노입자로 제작하였다. 소자의 제작은 p-Si기판에 실리콘산화막 터널층(5 nm 두께)을 건식 산화법으로 성장 후, 바나듐 실리사이드 금속박막을 RF 마그네트론 스퍼터 시스템을 이용하여 4~6 nm 두께로 터널 베리어 위에 증착하고, 그 위에 초고진공 마그네트론 스퍼터링을 이용하여 SiO2 컨트롤 산화막층 (20 nm)을 형성시켰다. 여기서 V3Si 나노입자 형성을 위해 급속 열처리법으로 질소 분위기에서 800$^{\circ}C$로 5초 동안 열처리하여 하였으며, 마지막으로 열 기화 시스템을 통하여 알루미늄 전극(직경 200 ${\mu}m$, 두께 200 nm)을 증착하여 소자를 제작하였다. 제작된 구조는 금속 산화막 반도체구조를 가지는 나노 부유게이트 커패시터이며, 제작된 시편은 투사전자현미경을 이용하여 나노입자의 크기와 균일성을 확인했다. 소자의 전기적인 측정을 E4980A capacitor parameter analyzer와 Agilent 81104A pulse pattern generator system을 이용한 전기용량-전압 측정을 통해 전하저장 효과 및 메모리 동작 특성들을 분석하고, 열처리 조건에 따라 형성되는 V3Si 의 조성을 엑스선 광전자 분광법을 이용하여 확인하였다.

• Korean Journal of Food Science and Technology
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• v.28 no.3
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• pp.514-520
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• 1996

The purpose of this study was to develop the production technology of modified starch. Corn starches were gamma irradiated at 0-110 kGy and the effect of irradiation dose levels on the physicochemical properties of corn starches were investigated. Blue value linearly decreased, while alkali number and solubility markedly increased as irradiation dose levels were increased. The optical transmittance increased as applied irradiation dose levels were increased in the temperature range of $65-95^{\circ}C.$ Water binding capacity and swelling power showed maximum value at 30 and 10 kGy, respectively and they tended to decrease thereafter. Gelatinization viscosity of the gamma irradiated starch considerably decreased as compared to that of the non-irradiated starch. Irradiation at 110kGy resulted in a marked reduction of peak viscosity and cooling viscosity at $30^{\circ}C$ by 100 and 300 times, respectively. The physicochemical properties of corn starch irradiated at 30 kGy were similar to those of commercial acid-modified starch, while those of corn starch irradiated at 100 kGy were similar to those if oxidized starch.

• Journal of Radiation Protection and Research
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• v.40 no.2
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• pp.92-100
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• 2015

For the purpose of improving the efficiency of the radiation impact assessment of dry interim storage facilities for the spent nuclear fuel of pressurized water reactors (PWRs), radiation impact assessment was performed after the application of sensitivity assessment according to the radiation source term designation method, development of a 2-step calculation technique, and cooling time credit. The present study successively designated radiation source terms in accordance with the cask arrangement order in the shielding building, assessed sensitivity, which affects direct dose, and confirmed that the radiation dosage of the external walls of the shielding building was dominantly affected by the two columns closest to the internal walls. In addition, in the case in which shielding buildings were introduced into storage facilities, the present study established and assessed the 2-step calculation technique, which can reduce the immense computational analysis time. Consequently, results similar to those from existing calculations were derived in approximately half the analysis time. Finally, when radiation source terms were established by adding the storage period of the storage casks successively stored in the storage facilities and the cooling period of the spent nuclear fuel, the radiation dose of the external walls of the buildings was confirmed to be approximately 40% lower than the calculated values; the cooling period was established as being identical. The present study was conducted to improve the efficiency of the Monte Carlo shielding analysis method for radiation impact assessment of interim storage facilities. If reliability is improved through the assessment of more diverse cases, the results of the present study can be used for the design of storage facilities and the establishment of site boundary standards.