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라흐만(Mohammad-Shiddiqur Rahman),이경환(Gyeong-Hwan Lee),이광성(Kwang-Sung Lee),정한식(Han-Shik Chung),정효민(Hyo-Min Jeong) 대한설비공학회 2009 대한설비공학회 학술발표대회논문집 Vol.2009 No.-
Renewability and pollutant free energy source makes hydrogen energy popular rapidly. Hydrogen gas pressure which is after passing through reciprocating compressor part has high pulsation wave form. A unit, snubber is used as compressor components to reduce the harmful pulsation waveform and to remove the impurities in the hydrogen gas. An experiment has been conducted to investigate the pulsation reduction performance of a steel pipe used in snubber system. The amplitude of pressure reduction were varied from 0.054 ~ 0.321 ㎪ for 10 hz to 60 hz motor speed. Compressor operation by motor with 10 to 60 hz were resulted in reduction of pressure pulsation from 16.415% to 35.151%. Pressure losses were varied from 0.001% ~ 0.759%, and pressure drop per centimeter of the steel pipe were varied from 0.0160 ~ 16.031 ㎩.
FEATURES OF PRESSURES IN THE PIPE FITTED BETWEEN TWO SNUBBERS IN HYDROGEN COMPRESSING SYSTEM
Mohammad Rahman(라흐만),Kyeonghwan Lee(이경환),Suprianto Wobowo(위보워),Jusik Woo(우주식),Hanshik Chung(정효민),i Hk Chung(정한식) 대한기계학회 2009 대한기계학회 춘추학술대회 Vol.2009 No.5
Compressing system is one of the most important processes in hydrogen gas handling: production, storage, distribution until using. High pulsation waveforms produced during hydrogen compression can be reduced by employing snubber in the system. There are some pipes to flow hydrogen between two snubbers. An experiment has been conducted to investigate the features of pressure in the pipe placed between snubbers in reciprocating compression system. In measuring amplitude FFT was done and pressure RMS values at input and output of one the pipe using data for 10, 20, 30, 50 and 60 ㎐ motor frequency of compressor operation. The pressure pulsation reductions are varied from 16.415~35.151% and corresponding pressure losses 0.007~0.759%.
M. Sq. Rahman(라흐만),G. H. Lee(이경환),K. S. Lee(이광성),H. S. Chung(정한식),H. M. Jeong(정효민) 대한기계학회 2008 대한기계학회 춘추학술대회 Vol.2008 No.10
Put Renewability and pollutant free energy source makes hydrogen energy popular rapidly. Hydrogen gas pressure which is after passing through reciprocating compressor part has high pulsation wave form. A unit, snubber is used as compressor components to reduce the harmful pulsation waveform and to remove the impurities in the hydrogen gas. An experiment has been conducted to investigate the pulsation reduction performance of different arrangement of snubber i.e. snubber array, single snubber in reciprocating compression system. The single snubber is able to reduce amplitude 55.947% ~ 58.248% (0.444, 0.786, 1.073 and 1.18 ㎪) with 0.475% ~ 1.966% pressure loss. It is found that the pressure fluctuations are reduced from 90.1977% ~ 92.6336% with pressure loss 1.5013% ~ 4.9034% for compressor operation at different speed which ensure the good performance of snubber-array as pulsation damper over single snubber in hydrogen compressing system.
미나르 마드올 라흐만(Matiur Rahman Minar),따이 트안 투안(Thai Thanh Tuan),안희준(Heejune Ahn) 한국산업정보학회 2020 한국산업정보학회논문지 Vol.25 No.2
최근 이미지를 사용한 가상착용기술 (Virtual try-on: VTON)에 대한 일련의 연구들이 발표되었다. 이에 의상과 사용자 이미지를 사용한 대표적 방식 (SCMM 기반의 비-딥러닝 방식, 딥러닝 기반 VITON 과 CP-VITON)에 대해 인물의 자세 및 체형, 의상의 가려짐 정도, 의상의 특성 등에 따라 분석한 연구가 보고되었다. 본 논문에서는 이중 가장 좋은 성능을 보이는 CP-VTON의 문제점을 살펴보고 이에 따른 해결책을 제시한다. 구체적으로 대상인물의 분할 표현 문제, 교체 대상이 아닌 영역이 유지되지 못하는 문제, 합성 마스크 생성네트워크의 학습에 사용되는 비용함수 문제, 합성 네트워크의 마스크 문제를 지적하고 이를 개선하는 알고리즘을 제안하였다. 그 결과 SSIM 등에서 5%내외의 주관적으로는 상당한 개선을 보였다. Recently, a series of studies on virtual try-on (VTON) using images have been published. A comparison study analyzed representative methods, SCMM-based non-deep learning method, deep learning based VITON and CP-VITON, using costumes and user images according to the posture and body type of the person, the degree of occlusion of the clothes, and the characteristics of the clothes. In this paper, we tackle the problems observed in the best performing CP-VTON. The issues tackled are the problem of segmentation of the subject, pixel generation of un-intended area, missing warped cloth mask and the cost function used in the learning, and limited the algorithm to improve it. The results show some improvement in SSIM, and significantly in subjective evaluation.
이산화염소에 대한 거짓쌀도둑거저리의 회피행동과 이를 억제하는 열처리 효과
김용균,수닐쿠마르,마버버라흐만,권혁,천용식,나자현,김욱,Kim, Yonggyun,Kumar, Sunil,Rahman, M. Mahbubur,Kwon, Hyeok,Chun, Yongsik,Na, Jahyun,Kim, Wook 한국응용곤충학회 2015 한국응용곤충학회지 Vol.54 No.3
이산화염소($ClO_2$) 훈증제는 살충효과를 나타낸다. 그러나 일부 곤충은 이산화염소에 대해 회피행동을 보여, 이 훈증제에 대한 방제효율을 크게 떨어뜨리고 있다. 본 연구는 이를 해결하기 위해 이산화염소 처리에 열처리를 추가하여 곤충의 이산화염소에 대한 회피행동을 줄여 살충효과를 극대화하는 전략을 세웠다. 이산화염소 훈증 처리는 거짓쌀도둑거저리(Tribolium castaneum)에 대해 살충효과를 주었으며, 시험 곤충이 노출된 조건에서 12 시간 처리할 때 유충에 대해서 383.67 ppm (153.63 - 955.78 ppm: 95% 신뢰구간), 성충에 대해서 397.75 ppm (354.46 - 446.13 ppm: 95% 신뢰구간)의 반수치사농도를 나타냈다. 그러나 먹이인 밀가루를 충분히 제공한 상태에서 이산화염소를 처리하면, 처리 약제에 반응하여 시험 곤충이 먹이 속으로 들어가는 회피행동을 보이면서 방제효과는 크게 낮아졌다. Y 튜브를 이용한 이 곤충의 먹이 선호성 행동을 분석한 결과 거짓쌀도둑거저리 성충은 이산화염소가 처리된 먹이를 회피하는 행동을 보였다. 그러나 촉각을 제거한 경우 이러한 회피행동은 둔화 되었다. 거짓쌀도둑거저리에 6 시간 동안 $46^{\circ}C$ 열처리를 하면 살충효과는 10% 이하로 낮지만, 처리된 성충들이 먹이 밖으로 나와 있는 것을 관찰하였다. 반면 400 ppm의 이산화염소를 단독으로 6 시간 처리한 결과 회피행동에 따라 전혀 살충효과를 보이지 않았다. 그러나 $46^{\circ}C$ 열처리와 400 ppm의 이산화염소를 병행하여 6 시간 처리한 결과 살충효과는 95%로 크게 증가하였다. 따라서 열처리는 거짓쌀도둑거저리의 이산화염소에 대한 회피행동을 억제하여 살충효과를 증가시켰다. Chlorine dioxide ($ClO_2$) can be used as a fumigant to kill insects. However, some insects can exhibit an evasive behavior from chlorine dioxide. This evasive behavior decreases the efficiency of the insecticidal activity of chlorine dioxide. This study tested a hypothesis that heat treatment suppresses the evasive behavior and synergizes the control efficacy of chlorine dioxide. Chlorine dioxide fumigation killed the red flour beetle, Tribolium castaneum, under direct exposure condition to the chemical for 12 h with median lethal concentrations of 383.67 ppm (153.63 - 955.78 ppm: 95% confidence interval) for larvae and 397.75 ppm (354.46 - 446.13 ppm: 95% confidence interval) for adults. However, when they were treated with enough diet flour, they exhibited an evasive behavior by entering the diet, which significantly decreased the control efficacy of the fumigant. To clarify the evasive behavior, the choice test of the adults were performed in Y tube arena. The test adults significantly avoided the diet treated with chlorine dioxide, while the antennatectomized adults lost the avoidance behavior. Heat treatment using $46^{\circ}C$ for 6 h killed only 10% or less of T. castaneum. Interestingly, most adults were observed to come out of the diet under the heat treatment. Chlorine dioxide treatment even at 400 ppm for 6 h did not kill any T. castaneum. However, the combined treatment of chlorine dioxide with the heat treatment for 6 h resulted in 95% mortality. These results indicated that heat treatment suppressed the evasive behavior of T. castaneum and synergized the control efficacy of the chlorine dioxide fumigant.
이경환 (G. H. Lee ),라흐만 (M. Sq. Rahman ),김철표 (C. P. Kim ),정태휘 (T. W. Joung ),정효민(H. M. Jeong),정한식 (H. S. Chung ) 한국동력기계공학회 2009 한국동력기계공학회 학술대회 논문집 Vol.2009 No.6
Numerical analysis information of a complex discharge-passage will be very useful to improve hydrogen compression system. General information about an internal gas flow is presented by numerical analysis approach. Relating with hydrogen compressing system, which have an important role in hydrogen energy utilization, this should be a useful tool to observe the flow quickly and clearly. Flow characteristic analysis, including pressure and turbulence kinetic energy distribution of hydrogen gas from cylinder going to the chamber of a reciprocating compressor are presented in this paper. Discharge-passage model is designed based on real model of hydrogen compressor. Pressure boundary conditions are applied considering the real condition of operating system. The result shows pressure and turbulence kinetic energy are not distributed uniformly along the passage of the hydrogen compressing system. Path line or particles tracks help to demonstrate flow characteristics inside the passage. The existence of vortices and flow direction can be precisely predicted. Based on this result, the design improvement should be done. Consequently, development of the better hydrogen compressing system will be achieved.