• Transactions of the Korean Society of Mechanical Engineers A
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• v.37 no.6
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• pp.723-730
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• 2013

The speed-limit regulation on a turnout is the main factor inhibiting the speed-up of conventional lines. The specified speed for a train moving through a turnout system is lower than that for a train traveling over the general track. This is done to ensure the running safety of a railway vehicle moving through a turnout. In this study, the shape change example of the guard rail component of a turnout in the Daegu Metropolitan Transit Corporation (DTRO) system was studied. A theoretical examination of the geometrical interaction formula according to wheel/rail shape at the turnout was conducted. Running safety analysis by changing the length of the guard rail on the F10/F12 turnout using the developed analysis techniques (by VI-Rail) was achieved, and the effect on railway safety was examined accordingly.

• The Korean Journal of Nuclear Medicine
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• v.36 no.5
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• pp.306-313
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• 2002

Purpose: Diuretic renography (DR) can be false negative in patients with upper urinary tract obstruction due to low compliance of the renal pelvis. Delayed parenchymal transit (DPT) may be a valuable sign in case of false negative DR. We compared the diagnostic values of DR and DPT during Tc-99m MAG3 diuretic scan in adults with suspected unilateral obstructive uropathy. Materials and Methods: Fifty-four patients(male:female=30:24, age: $40.7{\pm}15.5$ yrs) who underwent Tc-99m MAG3 diuretic scan due to suspicious unilateral obstructive uropathy were analyzed. DR with a $T_{1/2}\;of\;>\;15min$ was considered as positive for obstruction. DPT was considered to be present when there was delayed appearance of radioactivity in the renal pelvis and prolonged retention of radioactivity in the renal parenchyma. The renal area ratio was defined as the ratio of pixel number of hydronephrotic kidney over that of normal contralateral at $1{\sim}2min$ images. Definition of obstruction was improved hydronephrosis after intervention, or aggravated hydronephrosis without intervention. Non-obstruction was defined as unchanged hydronephrosis over 6 months. Results: Twenty-six renal units had obstruction and 28 no obstruction. The sensitivities of DR and DPT were 69% (18/26) and 50% (13/26) respectively. Two renal units with DPT but negative DR showed the renal area ratio of <1.1. Among the 20 obstructive renal units with DPT or positive DR, 13 with DPT had lower renal area ratio than 7 renal units without DPT ($0.97{\pm}0.20\;vs\;1.30{\pm}0.41,\;p<0.05$). Differential renal function was not significantly different between these groups. DPT correctly diagnosed all renal units with non-obstruction (specificity 100%), while the specificity of DR was 89% (25/28). Conclusion: DPT during Tc-99m MAG3 diuretic scan may be a valuable sign in diagnosing urinary obstruction especially in patients with false negative DR and early HN.

• Investigative Magnetic Resonance Imaging
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• v.7 no.2
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• pp.116-123
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• 2003

Purpose : The present study was undertaken to evaluate the usefulness of cerebral diffusion (DWI) and perfusion MR imaging (PWI) in rabbit models with hyperacute cerebral ischemic infarction. Materials and Methods : Experimental cerebral infarction were induced by direct injection of mixture of Histoacryl glue, lipiodol, and tungsten powder into the internal cerebral artery of 6 New-Zealand white rabbits, and they underwent conventional T1 and T2 weighted MR imaging, DWI, and PWI within 1 hour after the occlusion of internal cerebral artery. The PWI scan for each rabbit was obtained at the level of lateral ventricle and 1cm cranial to the basal ganglia. By postprocessing using special imaging software, perfusion images including cerebral blood volume (CBV), cerebral blood flow (CBF), and mean transit time (MTT) maps were obtained. The detection of infarcted lesion were evaluated on both perfusion maps and DWI. MTT difference time were measured in the perfusion defect lesion and symmetric contralateral normal cerebral hemisphere. Results : In all rabbits, there was no abnormal signal intensity on T2WI. But on DWI, abnormal high signal intensity, suggesting cerebral infarction, were detected in all rabbits. PWI (rCBV, CBF and MTT map) also showed perfusion defect in all rabbits. In four rabbits, the calculated square of perfusion defect in MTT map is larger than that of CBF map and in two rabbits, the calculated size of perfusion defect in MTT map and CBF map is same. Any rabbits do not show larger perfusion defect on CBF map than MTT map. In comparison between CBF map and DWI, 3 rabbits show larger square of lesion on CBF map than on DWI. The others shows same square of lesion on both technique. The size of lesion shown in 6 MTT map were larger than DWI. In three cases, the size of lesion shown in CBF map is equal to DWI. But these were smaller than MTT map. The calculated square of lesion in CBF map, equal to that of DWI and smaller than MTT map was three. And in one case, the calculated square of perfusion defect in MTT map was largest, and that of DWI was smallest. Conclusion : DWI and PWI may be useful in diagnosing hyperacute cerebral ischemic infarction and in e-valuating the cerebral hemodynamics in the rabbits.

• Proceedings of the Korean Information Science Society Conference
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• 2005.11a
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• pp.448-450
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• 2005

최근 급격히 늘어나는 사용자 트래픽을 효율적으로 관리하고, 다양한 사용자 SLA를 만족 시키기 위해서는 송.수신측의 필요한 만큼의 트래픽의 통과만을 허용할 수 있는 대역폭 제한이 필요하다. 그러나, 기존에 제시된 대역폭 조절 방식은 이더넷에 적합하지 않거나 또는 너무 복잡하여 EFM(Ethernet for First Mile)에 적용하기 어려움이 있었다. 본 논문에서는 효과적이고, 이더넷에 적용하기 적합한 대역폭 조절 방법인 속도 계산(Rate Calculation)메커니즘을 제안하며, 제안한 메커니즘에 대한 시뮬레이션을 통한 성능분석을 수행한다.

• The Korea Beekeeping Bulletin
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• s.330
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• pp.66-67
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• 2008

미리내 회사 직원의 한사람으로 인해 밀원주가 탄생하게 되었다. 직원의 한사람은 미국에서 벌꿀 제조 기술과 노화우를 국내에 전수하고자 양봉관련 업체를 방문하였으나 관심부족으로 인하여 시판하지 못하는 처지에 놓여 있었으나 직원의 본 고향인 경기도 연천 미리내 회사 측에서 제의받고 '밀월(蜜月)'을 제조 출시하게 되었다. 밀원주는 순수 국내산 아카시아꿀을 사용하여 제품을 생산 할 계획이며, 고가의 주조원료임에도 불구하고 제품의 신뢰도 강화를 위해 모든 원료는 한국양봉협회의 엄격한 품질검사를 통과한 국내산 아카시아꿀로 제한하고 있으며, 또한 아카시아꿀의 부드러우면서도 강한 맛과 향을 잘 반영할 수 있도록 모든 공정을 철저히 관리하고 있다. 더욱 소비자의 신뢰와 사랑을 받을 수 있는 대한민국 대표 주류제조업체로 발전시켜 나가기위한 마케팅전략을 펴 나갈 계획이라고 말했다.

• Proceedings of the KIPE Conference
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• 2014.07a
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• pp.277-278
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• 2014

본 논문은 저 대기전력의 구현이 가능하며 출력전압을 정확하게 제어할 수 있는 플라이백 컨버터 제어방식을 제안한다. 제안 방식은 모든 절연 형 컨버터에 적용 가능하고, 2차 측에 PFM(Pulse Frequency Modulation) IC를 위치시켜 정확한 출력전압 제어가 가능하다. 또한, 1,2차 측간에 신호 전달을 위하여 기존에 사용되는 TL431과 포토커플러가 아닌 Y-capacitor와 Low-Pass-Filter를 적용하여, 저 대기전력 구현이 가능하다. 제안방식의 타당성을 검증하기 위하여 이론적 해석과 시뮬레이션을 통하여 가능성을 확인하였다.

• Proceedings of the KIEE Conference
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• 2001.07d
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• pp.2060-2062
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• 2001

전기를 에너지원으로 사용하는 각 종 부하는 가정, 공장 및 상가 등에 널리 분산되어 있고, 여기에 전기를 생산 공급하는 발전기도 지역적으로 분산되어 병렬운전이 되고 있다. 새로운 발전기가 병렬운전에 참여하기 위해서는 기존 운전되고 있는 전력계통과의 전압, 주파수, 상회전, 위상이 일치하여야 한다. 만약 이들 조건이 갖추어지지 않은 상태에서 임의 병렬 접속을 시도하게 되면 해당 발전기는 물론 전체 계통에 충격과 손상을 초래할 수 있다. 양측의 전압과 주파수 비교는 상용 계측기를 사용하여 비교적 쉽게 할 수 있느나, 상회전 방향과 위상차의 판별에는 세심한 주의가 필요하다. 최근의 발전기에는 병렬 운전 조건을 자동으로 조정, 확인을 하는 장치를 채용하고 있으며 구체적인 회로구성과 동작원리를 여기에서 살펴보았다. 병렬 접속이 이루어진 후 발전기 별 전력 분담과, 계통 주파수 변동에 따라 자동으로 발전기 출력 제어가 이루어지는 기능이 터빈 조속기 측에 설정되어 사용된다.

• Proceedings of the KIPE Conference
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• 2019.07a
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• pp.338-339
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• 2019

본 논문에서는 LCL 필터를 사용하는 계통연계형 인버터에서 시스템을 안정시키기 위해 피드백 경로에 2차 저역 통과 필터(LPF)가 사용되었을 때 전류센서의 위치에 따른 출력 전류의 고조파 성분을 분석한다. LCL 필터를 사용하는 계통 연계형 인버터에서는 필터의 공진으로 시스템은 불안정해 지기 쉬우며 또한 안정조건은 전류센서의 위치에 따라서 바뀐다. 전류센서의 위치에 따라 바뀌는 계통측 전류의 고조파 성분을 시뮬레이션을 통해 분석한다.

• Journal of the Korean Magnetics Society
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• v.7 no.6
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• pp.314-320
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• 1997

We have observed the orientation behavior of acicular iron oxides in magnetic layer of the particular magnetic tape after magnetic paint was coated on polyester film. As results of the static orientation, orientation of iron oxides come to the maximum at the front and the back of orientation magnets, but it was a litter lower at the back than at the front, and it slowly decreases and come to the constant level after passing through the orientation magnets. In case of edge portion to be futher away from center in the coated film, the orientation of iron oxides in magnetic layer come to worse than that of the center. We think it is owing to the shape and the magnetic magnitude of orientation magnets. The results of the dynamic orientation are as follows. As the orientation of iron oxides in the particulated magnetic tape is higher, the output properties of tape come to better than ever. And the orientation of iron oxides can be changed by drying condition, as result, the output properties of tape can be also. Therefore we think the considrations of the design of orientation magnets and the control of drying condition are needed to improve output properties of the particulated magnetic tape.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.19 no.8
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• pp.131-137
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• 2005

The purpose of this paper is to evaluate the axial magnetic flux measurement could be used as a tool of the condition monitoring system for the induction motor and to develope the diagnostic algerian for the electric motors. The magnetic leakage flux signal is captured by the flux coil located at the end of motor without the disturbance of the operation. And the signal is analyzed both time and frequency bases to detect the failure of the motor. Specific signature can be described in time and frequency domain for each faults of the motor. The spectrum of the signal was found more useful for the monitoring purpose. The supply voltage imbalance and tin to turn failure of the stator winding could be detected by analysing the specific sidebands of the axial flux and sideband of the rotor bar pass frequency with the high resolution spectrum. The goal of this study verity that the axial flux measurement for the induction motor is a powerful tool for the diagnostic method and develope the algorithm to detect the fault.