해상풍력 해저케이블 하역용 유압식 코일링 암 구조설계 및 해석

김명환,김동현,오민우,Kim, Myung-Hwan,Kim, Dong-Hyun,Oh, Min-Woo 한국전산구조공학회 2013 한국전산구조공학회논문집 Vol.26 No.1

본 논문에서는 해저케이블 부두 하역용 장비인 코일링 암(coiling arm)에 대한 국산화 자체개발 내용 중 구조설계 및 해석결과 내용을 제시하였다. 상세 구조설계를 위해 3차원 CAD 프로그램을 이용하여 고 정밀도의 모델링을 수행하였고, 유한요소 기법을 이용하여 전산구조해석을 수행하였다. 코일링 암의 활용 목적에 맞추어 하역대상 케이블을 선박에서 케이블 탱크로 하역시 효과적으로 가이드 할 수 있도록 베어링 및 롤러 부품을 설계하여 메인 암이 회전하고 케이블 가이드가 이동할 수 있도록 하였고, 기존의 외국 모델에서 사용하던 와이어 및 모터 시스템을 이용한 케이블 가이드 작동방식을 유압 시스템을 이용한 작동방식으로 변경하여 원가절감을 달성하면서 사용자가 직관적으로 작동할 수 있도록 설계하였다. 장비 자체의 자중 및 하역 케이블 하중조건에 대한 응력 해석을 수행하였고, 유압시스템의 과작동에 따른 파손 가능성을 고려하였다. 케이블 가이드의 운동 및 설치 지면의 경사도에 따른 전복 안전성 해석을 수행하였으며, 설치장소의 풍하중 효과도 추가로 고려하였다. 본 연구를 통해 기존 수입품 코일링 암의 작동방식 개선과 독자적인 구조설계 및 해석 방법을 확립하였으며, 실제 국내 최초로 자체 개발된 제품의 현장설치 완료 및 하역작업의 효율적이고 정상적인 운영을 완료 및 검증하였다. Structural design and analysis of a coiling arm unloading machine for submarine cable have been originally conducted in this study. Three-dimensional CAD modeling process is practically applied for the structural design in detail. Finite element method(FEM) and multi-body dynamics(MBD) analyses are also used to verify the safety and required motions of the designed coiling arm structure. The effective moving functions of the designed coiling arm with respect to rotational and radial motions are achieved by adopting bearing-roller mechanical parts and hydraulic system. Critical design loading conditions due to its self weight, carrying cables, offshore wind, and hydraulic system over operation conditions are considered for the present structural analyses. In addition, possible inclined ground conditions for the installation of the designed coiling arm are also considered to verify overturn stability. The present hydraulic type coiling arm system is originally designed and developed in this study. The developed coiling arm has been installed at a harbor, successfully tested its operational functions, and finished practical unloading mission of the submarine cable.

도파로공진을 이용한 슬롯도파로 포화흡수체 반사기

김명환,김상인,Kim, Myung-Hwan,Kim, Sang-In 한국광학회 2011 한국광학회지 Vol.22 No.3

본 논문에서는 도파모드공진을 이용한 포화흡수체 반사기를 제안하였다. 포화흡수체로는 탄소나노튜브(CNT)를 사용하였다. 제안된 반사기는 CNT의 두께 변화 없이 modulation depth를 키울 수 있다는 장점이 있다. 제안하는 반사기의 fill factor(F)와 CNT의 두께변화에 따른 modulation depth, 대역폭, 포화되었을 때의 최대 반사율의 특징을 알아보았다. 제안된 반사기는 포화에너지를 줄일 수 있다는 장점이 있고, 100~200nm 얇은 CNT박막에서 50배정도 줄어드는 것을 확인 하였다. We propose a saturable absorber reflector based on guided-mode resonance. A carbon nanotube is used as a saturable absorber. By tuning the fill factor, modulation depth can be increased without a change of height of the CNT. We investigate the reflector properties such as modulation depth, bandwidth and peak reflectance as a function of the height of the CNT and the fill factor. The advantage of the proposed reflector is that it can reduce saturation energy by 50 times compared with CNT thin film of 100~200nm.

생강 삼투압 건조 시 물질이동 특성과 품질에 미치는 효과

김명환,Kim, Myung-Hwan 한국응용생명화학회 1998 Applied Biological Chemistry (Appl Biol Chem) Vol.43 No.4

생강의 삼투압 건조 중 설탕용액의 농도와 온도 및 침지시간에 따른 내부 물질이동을 생강 내부의 수분손실, 설탕흡수, 몰랄농도 및 속도매개 변수로써 조사하였고 갈색화 반응정도를 평가하였으며 데치기와 삼투압건조를 각각 거친 후 열풍건조 시킨 것에 대하여 복원 시 텍스쳐를 비교하였다. 용액의 농도와 온도가 증가함에 따라서 수분손실, 설탕흡수, 몰랄농도 및 속도매개 변수가 증가하였으며, 용액농도와 온도에 관계없이 수분손실, 설탕흡수, 몰랄농도는 초기 3분간 침지과정에서 빠르게 이루어진 후 증가현상이 둔화되었다. $80^{\circ}C$의 60 Brix 설탕용액에서 18분간 침지하였을 때 40.05 g 수분손실/100 g생강으로 초기 수분함량 83.02%(wet basis) 기준으로 약 52%의 수분을 제거하는 효과를 갖는다. 속도매개 변수는 설탕용액의 농도 보다는 온도에 의한 변화가 컸다. 갈색화 정도는 설탕용액의 농도와 온도에 관계없이 15분간 침지시켰을 때 가장 낮은 O.D.값을 나타내었으며, 대조구(O.D.=0.132)와 비교하였을 때 $80^{\circ}C$에서 40 또는 50 Brix의 설탕용액에 15분간 침지시킨 것이 가장 낮은 값(O.D.=0.027)을 보였다. 데치기 공정을 시킨 것과 대조구를 열풍건조 시킨 다음 끓는 물에서 3분간 복원시킨 후의 관통힘은 차이가 나타나지 않았으나 삼투압 건조시킨 생강은 대조구 보다 $22{\sim}34%$ 적게 나타났다. Internal mass transfer during osmotic dehydration of gingers in sugar solution was examined as a function of concentration, temperature and immersion time of those solutions using moisture loss, sugar gain, molality and rate parameter. Influence of osmotic dehydration on browning reaction and texture properties of air dried rehydrated was also evaluated. Increasing the concentration and temperature of sugar solutions increased moisture loss, sugar gain, molality and rate parameter. Water loss and sugar gain were rapid in the first 3 min and then changed gentle slope. Moisture loss during osmotic dehydration using a sugar solution $(60\;Brix,\;80^{\circ}C)$ with 18 min immersion time was 40.05 g moisture/100 g wet ginger which was 52% reduction of initial moisture content in ginger (83.02%, wet basis). The changes of rate parameter were more affected by temperature than by concentration of sugar solution. Minimum browning degree (O.D.=0.027) was carried out by osmotic dehydration in sugar solution $(40\;or\;50\;Brix,\;80^{\circ}C)$ with 15 min immersion time compared to control (O.D.=0.132). Influence of osmotic dehydration on puncture forces of 3 min rehydrated ginger in boiling water were $22{\sim}34%$ of reduction, while blanching treatment had not affected compared to those of control.

자당 지방산 에스테르 또는 이소말토올리고당 첨가가 저장 쌀밥의 텍스쳐에 미치는 영향

김명환,김병용,김성곤 ( Myung Hwan Kim,Byung Yong Kim,Sung Kon Kim ) 한국산업식품공학회 1997 산업 식품공학 Vol.1 No.2

첨가물에 따른 저장 쌀밥의 텍스쳐 특성

김명환,이상규,김성곤 ( Myung Hwan Kim,Sang Kyu Lee,Sung Kon Kim ) 한국응용생명화학회 1997 Applied Biological Chemistry (Appl Biol Chem) Vol.40 No.5

The effect of sucrose fatty acid ester(SE, 0∼0.5%, w/w) and oligosaccharide(OS, 0∼1.0%, w/w) additions on texture properties, hardness(H), stickiness(-H), stickiness/hardness(-H/H) and elastic recovery (b/a) of cooked rice stored at 20℃ were studied. The H of stored cooked rice decreased with increasing storage time. The addition of SE and OS showed lower H value than control throughout the storage period up to 12hrs and after 8hrs of storage time, respectively. The -H of stored cooked rice increased with increasing storage time. The -H value of SE added cooked rice showed much lower than that of the control in the early stage of the storage and then almost the same value as that of control. The control and SE or OS added cooked rice resulted the value of -H/H between 0.15 and 0.20, which had been found as acceptable textural parameters, after 10hrs of storage at 20℃. The b/a of stored cooked rice decreased with increasing storage time, but was not significantly affected by additives. After 15 days of storage at 4℃, the addition of SE had greater effect on the reduction of hardness of stored cooked rice than that of OS.

우리나라 담석증의 역학에 관한 연구 ; 전국적 다기관 협동 조사 성적

김명환 ( Myung Hwan Kim ),오희철 ( Hee Choul Ohrr ),정재복 ( Jae Bock Chung ),김창덕 ( Chang Duck Kim ),강진경 ( Jin Kyung Kang ),고문수 ( Moon Soo Koh ),김남재 ( Nam Jae Kim ),김대곤 ( Dae Ghon Kim ),김성국 ( Sung Kook Kim ),김 대한소화기학회 1999 대한소화기학회지 Vol.32 No.5

Background/Aims: To understand the epidemiologic characteristics of gallstone disease in Korea and to evaluate the chronological changes of gallstone disease, the authors performed this prospective nationwide cooperative study. Methods: The subjects were 1,263 patients with gallstone. They were hospitalized at 19 hospitals in Korea from February to July, 1997. The study protocals were recorded on 1,263 patients and gallstones were removed from 1,133 patients and their chemical compositions were analyzed. Results: Among total patients with gallstone, the proportions of patients with gallbladder, common bile duct (CBD) and intrahepatic duct (IHD) stones were 64.0%, 21.9%, and 14.1%, respectively. Male to female ratio was 1 versus 1.3. The gallbladder stones were categorized as cholesterol (58.1%), black pigment (25.2%) and brown pigment (12.1%) stones. The CBD stones were classified into brown pigment (76.1% ), cholesterol (18.4%) and black pigment (3.5%) stones.

등가모델링기법을 이용한 5MW급 부유식 해상용 풍력발전기 구조동역학해석

김명환(Myung-Hwan Kim),김동현(Dong-Hyun Kim),김동환(Dong-Hwan Kim),김봉영(Bong-Yung Kim) 한국소음진동공학회 2011 한국소음진동공학회 학술대회논문집 Vol.2011 No.10

In this study, the computational structural dynamic modeling of floating offshore wind turbine system is presented using efficient equivalent modeling technique. Structural dynamic behaviors of the offshore floating platform with 5MW wind turbine system have been analyzed using computational multi-body dynamics based on the finite element method. The considered platform configuration of the present offshore wind turbine model is the typical spar-buoy type. Equivalent stiffness and damping properties of the floating platform were extracted from the results of the baseline model. Dynamic responses for the floating wind turbine models are presented and compared to investigate its structural dynamic characteristics. It is important shown that the results of the present equivalent modeling technique show good and reasonable agreements with those by the fully coupled analysis considering complex floating body dynamics.

지역복지지표의 설정과 그 적용 - 강원도 시군의 사례 -

김명환 ( Kim Myung - Hwan ) 한국행정학회 1992 韓國行政學報 Vol.26 No.2

쌀의 첨지조건이 취반후 조직감에 미치는 영향

김명환(Kim, Myung Hwan) 한국식품과학회 1992 한국식품과학회지 Vol.24 No.5

알카리성 인산-과망간산 용액을 이용한 AZ31 마그네슘 합금의 친환경 화성 처리 및 화성 피막의 특성 평가

김명환(Myung-Hwan Kim),이만식(Man-Sig Lee),곽삼탁(Sam-Tag Kwag),문명준(Myung-Jun Moon) 한국표면공학회 2011 한국표면공학회지 Vol.44 No.3

A uniform chromium-free conversion coating treated with an alkaline phosphate- permanganate solution was formed on the AZ 31 magnesium alloy. The effect of acid pickling on the morphology and on the corrosion resistance of the alkaline phosphate-permanganate conversion coating was investigated. The chemical composition and phase structure of conversion coating layer were determined via optical microscopy, SEM, EDS, XPS and XRD. Results show that the conversion coatings are relatively uniform and continuous, with thickness 1.8 to 2.4 ㎛. The alkaline phosphate-permanganate conversion coating was mainly composed of elements Mg, O, P, Al and Mn. The conversion-coated layers were stable compounds of magnesium oxide and spinel (MgAl₂O₄). These compounds were excellent inhibitors to corrosion. The electrochemical corrosion behaviors of coatings in 3.5 wt.% NaCl solutions were evaluated by electrochemical impedance spectroscopy, potentiodynamic polarization technique. EIS results showed a polarization resistance of 0.1 kΩ for the untreated Mg and 16 kΩ for the alkaline phosphate-permanganate conversion treatment sample, giving an improvement of about 160 times. The results of the electrochemical measurements demonstrated that the corrosion resistance of the AZ 31 magnesium alloy was improved by the alkaline phosphate-permanganate conversion treatment.