• 전자공학회논문지A
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• 제32A권2호
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• pp.19-30
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• 1995

Diffraction patterns of the copolarized and the crosspolarized total electric fields by a spherical air cavity in a dielectric medium are analyzed in the forward near-field region when the wavelength of the incident plane wave is comparable to one half of the cavity radius. It is shown that double nulls and dips of the copolarized and the crosspolarized total electric fields exist in the measurement plane tansverse to the propagating direction of the incident field, and their dependences on the frequency, the distance of the measurement plane, and the measurement angle are analyzed.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2003년도 춘계학술대회 논문집
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• pp.126-132
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• 2003

Recently with the rapid development in mobile communication, the mobile phone are utilized in many fields of railway system within country and abroad and its use tends to increase continuously. In the railway system, the applicable realm is spreaded to the fields of railway signal communication, railway operating, track maintenance, reservation and information service, also its role is expected to increase. In this thesis, we are surveying the usage application of home and abroad mobile phone in railway system. Studying the present condition of mobile communication in railway system, we are viewing the application plan and the direction of development.

• 한국가시화정보학회:학술대회논문집
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• 한국가시화정보학회 2003년도 추계학술대회 논문집
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• pp.59-62
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• 2003

The near wake behind a sinusoidal cylinder at Re=5200 has been investigated using DPIV system. The velocity fields, streamlines and vorticity contours of the mean flow were compared at the nodal, saddle and middle planes with those of a right circular cylinder. For the sinusoidal cylinder, the vortex core moves downstream and the vortex formation region is expanded in streamwise direction while suppressed in transverse direction at the nodal plane. At the saddle and the middle plane the vortex spread in both streamwise and transverse directions, forming the maximum vortex region at the saddle plane.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2000년도 봄 학술발표회 논문집
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• pp.153-158
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• 2000

This study was carried out in order to investigate the relationship roundness of fly ashes and fluidity of fly ash cement paste. electrostatic precipitator system in coal-fired power plant have many successive collection fields in the direction of flue gas travel. In experiment, the roundness of fly ashes collected from the same location had similar values regardless of the load or boiler, and they increased going from the 1st collection filed to third collection filed in the direction of gas movement. In considering the relation between roundness of fly ashes and fluidity of fly ash cement paste, it has a high correlation.

• 한국자기학회지
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• 제4권4호
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• pp.340-346
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• 1994

(200) 우선방위를 보이는 Co/Cu 인공초격자에 주자장과 보조자장 두자장을 동시에 가하는 경우 각각의 자장의 세기에 따른 금속인공초격자의 저항변화에 대해 연구하였다. 자장의 방향이 서로 같은 방향인 경우 자기저항곡선의 수평적 이동이 발생하였으며 서로 직각인 경우는 자기저항최대점의 분리현상이 발견되었다. 두자장간의 각도가 $45^{\circ}$인 경우는 위의 두현상이 복합적으로 나타났다. 이러한 이중자장에 의한 자기저항곡선의 변화는 이 연구에서 제안된 자장에 따른 인공초격자의 거시 적인 스핀정렬 모델에 의해 설명될 수 있었다.

• 한국조리학회지
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• 제13권3호
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• pp.207-219
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• 2007

The purpose of this study is finding the right direction to make the best career development systems for the employees in hotel industry in Korea. The condition of the best career development system is satisfaction from companies and employees each other. However, making that condition is not easy for every industry as well as for hotel industry over the world. In this respect, we can find the three directions of career development for applying the systems to the employees like strategy direction oriented, development direction oriented and employee satisfaction oriented. Among those directions, we have to find the best direction for individual satisfaction and organizational company satisfaction. This study will help to make and execute the plan for career development in real hotel industry fields, especially for the policy of human resources management. In this study, we can see the importance of employees' satisfaction for managing a hotel. The increasing productivity of the hotel eventually will be made from career development through employee satisfaction.

• 한국레이저가공학회지
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• 제5권3호
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• pp.1-8
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• 2002

Finite element analysis and experiment were peformed to estimate the fatigue strength for the lap joint of laser weld. To consider quantitatively residual stress which effects on the fatigue strength of the lap joint of laser weld, after three dimensional modeling for the longitudinal and transverse direction, residual stress fields in the weldment were calculated using thermo-elastic-plastic finite element analysis, then the equivalent fatigue stress considering the residual stress was obtained. To ensure reliability of calculated fatigue strength, fatigue tests were performed. The calculated and experimental results showed a good agreement. The fatigue strength considering a residual stress was lower than that of without considering a residual stress in the lap joint of laser welding. The fatigue strength in the transverse direction was higher than that of longitudinal direction.

• 한국자기학회지
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• 제13권3호
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• pp.127-132
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• 2003

자성유체의 자연대류는 부력 이외에 자기체적력이 존재하기 때문에 뉴턴유체와 다르다. 본 연구에서는 좌측 및 우측 벽면이 고온 및 저온으로 설정된 정방형 케비티 공간내에서 자성유체의 자연대류를 실험하였다 실험은 열전대에 의한 온도측정과 감온액정에 의한 가시화를 실시하였다. 그 결과 케비티 공간내 자성유체의 전열특성 및 외부에서 가하는 자장의 방향과 세기에 따라 자연대류가 제어됨을 알 수 있었다.

• Journal of Biosystems Engineering
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• 제42권4호
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• pp.235-241
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• 2017

Purpose: It is to develop an agricultural three-directional dumping vehicle that can help farmers reduce intensive labor when carrying heavy loads and for easy dumping. In addition, a novel mechanism was applied for controlling the direction of the tilting cargo box by using a single hydraulic cylinder and simple apparatus. The overturning safety was analyzed to provide safe-use ground slope region of the vehicle to be used at upland fields and orchards. Methods: The developed three-directional dumping vehicle was constructed using a cargo box, vehicle frame, driving components, lifting components, and controller. The novel mechanism of controlling the dumping direction involves the operation of two latching bars, which selectively release or collapse the connecting edge between the vehicle frame and cargo box. A multibody dynamics analysis software (RecurDynV8R5) was used to determine the safe-use ground slope area when tilting the cargo box at slopes. A computer analysis was conducted by increasing the ground slope while rotating the vehicle when the cargo box comprised loads of 300 and 500 kg and stacking heights of 40 and 80 cm, respectively. Results: The three-directional dumping vehicle was successfully manufactured, and the cargo box was tilted at $37^{\circ}$ and $35^{\circ}$ for dumping forward and sideways. The latching bars were manually and selectively collapsed with the vehicle frame to control the dumping direction. When forward dumping, the safe-use ground slope was over $20^{\circ}$ in all vehicle directions and loaded conditions. Conclusions: A three-directional dumping vehicle was developed to reduce labor-intensive work in the farming environment. The user can easily control the dumping direction by using the control panel. The vehicle was safe to be used in most of the Korean upland fields and orchards (area over 96%) for the forward dumping.

• 조명전기설비학회논문지
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• 제28권10호
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• pp.63-68
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• 2014

This paper deals with a methodology that applies the time-varying magnetic fields produced by the cloud discharges to find the direction of thunderstorm movement. We investigated the basic performance of the magnetic field measurement system composed of multi-turn loop-type sensors, the differential amplifier and active integrator. As a result, the response characteristics of the magnetic field sensor system to sinusoidal signals was excellent. The frequency bandwidth ranges from about 1 kHz to 500 kHz, the response sensitivity was 0.16mV/nT. In addition, we proposed the algorithm that determines the direction of lightning discharges using the comparison of the output signals of right-angled loop-type magnetic field sensors. The accuracy of the direction finding of lightning discharges is fairly well within the measurement error of less than $5^{\circ}$. The magnetic field measurement system proposed in this work can be used to track the direction of thunderstorm movement.