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Effect of corrosion on the ultimate strength of double hull oil tankers – Part I: stiffened panels
김도균,박대겸,Jeong Hwan Kim,김상진,김봉주,서정관,백점기 국제구조공학회 2012 Structural Engineering and Mechanics, An Int'l Jou Vol.42 No.4
Age-related problems especially corrosion and fatigue are normally suffered by weatherworn ships and aging offshore structures. The effect of corrosion is one of the important factors in the Common Structural Rule (CSR) guideline of the ship design based on a 20 or 25 years design life. The aim of this research is the clarification of the corrosion effect on ultimate strength of stiffened panels on various types of double hull oil tankers. In the case of ships, corrosion is a phenomenon caused by the ambient environment and it has different characteristics depending on the parts involved. Extensive research considering these characteristic have already done by previous researchers. Based on this data, the ultimate strength behavior of stiffened panels for four double hull oil tankers such as VLCC, Suezmax, Aframax, and Panamax classes are compared and analyzed. By considering hogging and sagging bending moments, the stiffened panels of the deck, inner bottom and outer bottom located far away from neutral axis of ship are assessed. The results of this paper will be useful in evaluating the ultimate strength of an oil tanker subjected to corrosion. These results will be an informative example to check the effect of ultimate strength of a stiffened panel according to corrosion addition from CSR for a given type of ship.
적혈구 침강속도에 대한 Westergren tube 각도, 온도 및 NaCl 농도가 미치는 영향
김도균,김영홍,유창준,Kim, Do-kyun,Kim, Young-hong,Yu, Chang-jun 대한수의학회 1996 大韓獸醫學會誌 Vol.36 No.1
Erythrocyte sedimentation rate is influenced by plasma protein, red cell itself and physiological conditions and it is clear that the measurement of erythrocyte sedimentation rate varies with technique and various environmental factors. The effect of temperature, angle of test tube, and osmobility with different percent of NaCl solution on erythrocyte sedimentation rate on sheep was determined by modified Westergren method. In sheep, as the angle of Westergren tube was decreased from $90^{\circ}$ to $45^{\circ}$, erythrocyte sedimentation rate was increased in both diluted plasma and NaCl solutions. As temperature was increased from $4^{\circ}C$ to $20^{\circ}C$ at $45^{\circ}$ angle. erythrocyte sedimentation rate was increased. In ruminants, this modified Westergren methods, erythrocyte 1 : plasma 9 instead of erythrocyte 4 : plasma 6(whole blood), enable them to have meanings as dog therefor, using this method, clinical can determine the erythrocyte sedimentation rate of ruminants for diagnosis. Because erythrocyte sedimentation rate was changed according to the angle of Westergren tube, temperature as erythrocyte diluted with NaCl, this study detected that the change of temperature, the angle of Westergren tube could change erythrocyte sedimentation rate by effecting red cell itself. The increase of osmobility owing to change of NaCl percent resulted in the decrease of rapid erythrocyte sedimentation rate. So this fact indicate that deformibility and the change of red cell volume have meaning in the change of erythrocyte sedimentation rate.
Effect of corrosion on the ultimate strength of double hull oil tankers – Part II: hull girders
김도균,박대겸,Dong Hee Park,Han Byul Kim,김봉주,서정관,백점기 국제구조공학회 2012 Structural Engineering and Mechanics, An Int'l Jou Vol.42 No.4
Numerous oil tanker losses have been reported and one of the possible causes of such casualties is caused by the structural failure of aging ship hulls in rough weather. In aging ships, corrosion and fatigue cracks are the two most important factors affecting structural safety and integrity. This research is about effect on hull girder ultimate strength behavior of double hull oil tanker according to corrosion after Part I: stiffened panel. Based on corrosion data of Part I (time-dependent corrosion wastage model and CSR corrosion model), when progressing corrosion of fourtypes of double hull oil tankers (VLCC, Suezmax, Aframax, and Panamax), the ultimate strength behavior of hull girder is compared and analyzed. In case of the ultimate strength behavior of hull girder, when occurring corrosion, the result under vertical and horizontal bending moment is analyzed. The effect of time-dependent corrosion wastage on the ultimate hull girder strength as well as the area, section modulus, and moment of inertia are also studied. The result of this research will be useful data to evaluate ultimate hull girder strength of corroded double hull oil tanker.
Study on the Injection System for Cyclotron Mass Spectrometry
김도균,J. Y. Kim,방형찬,C. C. Yun,J. W. Kim 한국물리학회 2011 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.59 No.23
The accelerator mass spectrometry (AMS) based on a cyclotron can be compact and economical compared to the commercial Tandem AMS. However, AMS cyclotrons previously built suffered largely from poor transmission efficiency. To improve the efficiency, it is important for the injection system to match the beam phase space with cyclotron acceptance. We plan to adopt a sawtooth rf buncher for longitudinal phase-space matching and a flat-topping rf system in the cyclotron for a larger phase acceptance. The beam optics for the injection line was studied using TRANSPORT and TRACE-3D, keeping a minimal number of beam line elements. The shapes of extraction electrodes and Einzel lens were simulated using IGUN. A prototype beam line is being constructed so that the beam measurements in comparison with calculation results will be used to reveal an optimal design.
리듐 2차 전지용 약극활물질 LiFePO<sub>4</sub>의 합성 조건에 다른 전기화학적 특성
김도균,박현민,정연욱,이준형,김정주,Kim, Do-Gyun,Park, Hyun-Min,Jeong, Yeon-Uk,Lee, Joon-Hyung,Kim, Jeong-Joo 한국세라믹학회 2006 한국세라믹학회지 Vol.43 No.2
[ $LiFePO_4$ ] is one of the promising materials for cathode material of secondary lithium batteries due to its high energy density, low cost, environmental friendliness and safety. $LiFePO_4$ was synthesized by the solid-state reaction method at 500 - 800°C. The crystal structure of $LiFePO_4$ was analyzed by X-ray powder diffraction. The samples synthesized at 600 and $700^{\circ}C$ showed a single phase of a olivine structure. The particle sizes were increased and the specific surface areas were decreased with heating temperatures. The electrochemical performance was investigated by coin cell test. The discharge capacities at 0.1 C-rate were 118 mAh/g and 112 mAh/g at $600^{\circ}C,\;700^{\circ}C$, respectively. In an attempt to improve the electrical conductivity of cathode materials, $LiFePO_4/graphite$ composite was prepared with various graphite contents. The electrical conductivity and discharge capacity were increased with increasing the graphite contents in composite samples. The rate capabilities at high current densities were also improved.
광양만 임해 매립지 느티나무 이식 이후의 연륜생장 특성
김도균,Kim Do-Gyun 한국조경학회 2006 韓國造景學會誌 Vol.33 No.6
This study was carried out to examine the tree-ring growth characteristics of Zelkova serrata Makino after replanting, for the built-up planting founds for stability of landscaped trees in the reclaimed land from the sea. the factors, many affecting the growths of Zelkova serrata Makino, were the replanting stress and drought. The growth reduction due to replanting and drought occurred in the replanting year and the following year. The mean sensitivity(year-to-year variation) and the coefficient of variation(tree-to-tree variation in a certain year) in tree rings of Zelkova serrate Makino, were higher in the poor soil sites than in the favourable soil ones. And the poor soil sites were the filled ground of improve soil and the covered ground of improve soil and the top ground of big mounding than mounding ground sites, especially soil hardness, alkali soil, high $Na^+\;and\;K^+,\;low\;Ca^{++}\;and\;Mg^{++}$ and T-C were the most crucial. We suggest technique development of the built-up planting ground for stability in the reclaimed land from the sea. The built-up planting grounds in reclaimed land from the sea, should be considered for the use of fair soil with the physical and chemical soil properties, -high level foundation of planting ground, and the prevention of disturbed soil-.
시뮬레이션 기반 수도권 리사이클링 센터 폐냉장고 전처리 공정 개선
김도균,강민구,최진영,박기진,공만식,Kim, Do Gyun,Kang, Min Koo,Choi, Jin Young,Park, Kiejin,Kong, Man-Sik 한국시뮬레이션학회 2013 한국시뮬레이션학회 논문지 Vol.22 No.4
본 논문에서는 수도권 리사이클링 센터 폐냉장고 전처리 공정의 성능 개선 방안에 관하여 연구하였다. 이를 위해 현행 전처리 공정을 기본 작업 단위로 구분하고 공정 별 작업 시간을 측정하여 ARENA를 이용한 모델링 및 성능 분석을 수행하였다. 또한 실무자의 경험과 선진 사례 등에 기반한 3가지 새로운 전처리 공정 대안을 생성한 후 ARENA를 이용한 모델링 및 시뮬레이션을 통해 평가하였다. 최종 선정된 대안은 현행 2-라인 공정을 1-라인으로 전환하고, 냉매를 회수하기 위한 별도의 셀라인을 도입하는 것을 포함한다. 본 연구 결과는 현재 새로운 전처리 공정 라인으로 설치되어 운영되고 있으며, 이전 공정에 비해 사이클 타임과 생산성 향상뿐만 아니라, 공간 활용률 측면에서도 크게 개선된 결과를 보였다. This paper studies the improvement of a pre-processing line for waste refrigerators in a metropolitan recycling center(MRC). We performed ARENA modeling and simulation by using work analysis and time measurement on the current processing line. Combined this result with some practical experiences from workers, we generated 3 alternatives to improve the current line and evaluated them by using ARENA simulation. The final decision selected consists of changing 2-line process into 1-line and having a separate cell-line for collecting refrigerant. Currently, the result of this study was applied to MRC by improving cycle time, throughput, and space utilization compared to the previous one.