초음파를 이용한 액체내의 공기방울 포획현상에 관한 연구

김용석,이희복,김용복 공주대학교 과학교육연구소 2002 과학교육연구 Vol.33 No.-

본 연구에서는 초음파에 의해 액체 내에서 공기방울을 포획하는 연구를 수행하였다. 초음파 진동자를 최소의 전력으로 구동하여 안정된 공기방울을 포획하기 위해서는 임피던스 매칭이 필요했다. 초음파진동자의 임피던스는 매우 크므로 임피던스 매칭을 위해 고주파 변압기와 인덕터를 제작하였다. 안정된 공기방울은 증류수를 100℃에서 10분간 끓여서 하루동안 서서히 냉각시켜 물속의 산소용존량이 0.3∼0.5㎎/ℓ일 때 포획되었다. 본 장치의 초음파 공진 주파수는 약 26㎑이었다. In this study the bubble captures phenomena by using supersonic transducers were investigated. The operating minimum power for supersonic transducers requires impedance matching for optimal capture of a stabilized bubble. Because the impedance supersonic transducers of was high, we made high frequency transformers and inductor for impedance matching. The stabilized bubble was captured in the distilled water which boiled at 100℃ for 10 minute and then cooled down for a day until the dissolution of oxygen reached at 0.3∼0.5㎎/ℓ In this experiment the frequency of the acoustic resonance appeared at about 26 ㎑.

쥐 태자 간의 동굴모세혈관과 적혈구모세포 이주에 관한 전자현미경적 연구

김용욱,김경용,이원복,이흥식 대한해부학회 1998 Anatomy & Cell Biology Vol.31 No.2

용접방법에 따른 하중전달 십자형 필렛 용접부의 피로특성

李龍福,吳炳德 한국공작기계학회 2002 한국공작기계학회 춘계학술대회논문집 Vol.2002 No.-

In this study, it was investigated about endurance limit and fatigue behavior of load carrying fillet welded cruciform joints according to welding methods of SMAW, SAW, MIG and FCAW commonly using for welding structures in present. Endurance limit carried out highly in the order of SMAW, MIG, SAW, FCAW and fatigue crack propagation ratio carried out lowly in the order of SMAW, MIG, FCAW, SAW. By these results, it is needed to use SMAW or MIG welding methods for welding structures with small welding capacity and SAW or FCAW methods for large welding structures after due consideration about economic gains and operation efficiency of welding. Fatigue crack propagation ratio is more effected by strength of welding materials than endurance limit of welding materials according to welding methods.

강 봉 맞대기 용접부의 피로 및 파단 특성

이용복 한국공작기계학회 2009 한국공작기계학회 춘계학술대회논문집 Vol.2009 No.-

SM45C steel rods using generally for machine components was selected and welded by butt-GMAW method for this study. And then it was studied about characteristics of fatigue behavior and fracture surfaces by rotary bending test. Fatigue strength in weld zone presents highly in order of the boundary between deposited metal zone and heat affected zone, deposited metal zone, heat affected zone. The region of infinite life by Haigh diagram presents highly in order of the boundary between deposited metal zone and heat affected zone, deposited metal zone, heat affected zone. Fatigue cracks in unnotched specimens of base metal and weld zone introduces simultaneously from extensive out-side of circumferential cross-sections and propagates to the other side indicating beach markings and dimples according to consolidation of fatigue cracks. Fatigue cracks in all of notched specimens introduces simultaneously in out-side of circumferential cross-sections by high stresses and propagates to center of it indicating beach markings.

비냉각 적외선 감지기용 비나듐 산화막의 전기전도기구

최용남,최복길,이규대 공주대학교 생산기술연구소 2001 論文集 Vol.9 No.-

Thin films of vanadium oxide(VO_(x)) have been deposited by r.f. magnetron sputtering from V_(2)O_(5) target in gas mixture of argon and oxygen. The oxygen/(oxygen+argon) partial pressure ratio is changed from 0% to 8%. Crystal structure, chemical composition and electrical properties of films sputter-deposited under different oxygen gas pressures have been characterized through XRD, AES, RBS and electrical conductivity measurements. All the films prepared below 8% O_(2) are amorphous, and those prepared without oxygen are gray indicating the presence of V_(2)O_(4) phase in the films. In order to measure the current-voltage characteristics and temperature dependence of conductance, devices of A1/VO_(x)/A1 sandwich structure have been fabricated. I-V characteristics are distinguished between linear and nonlinear region. In the low field region the conduction is due to Schottky emission, while at high field it changes to Fowler-Nordheim tunneling type conduction. The conductivity measurements have shown an Arrhenius dependence of the conductivity on the temperature.

람모한 로이(Raja Rammonhan Roy)의 종교관 : 신(god)에 대한 관념을 중심으로 On the idea of god

윤용복 서울대학교 종교문제연구소 2003 종교와 문화 Vol.0 No.9

김미료 소재로서 Di-D-Fructofuranose Dianhydride3의 물리 및 생리적 특성

박정복,김소자,최용진 한국미생물생명공학회 ( 구 한국산업미생물학회 ) 1996 한국미생물·생명공학회지 Vol.24 No.5

충치 원인균인 Streptococcus mutans와 유용 장내 세균인 각종 Bifidus 균주 증식에 미치는 di-D-fructofuranose dianhydrideIII(DFAIII)의 효과를 조사 분석하여 DFAIII의 생리 효과를 간접적으로 분석하였다. DFAIII는 Arthrobacter sp. A-6 토양 분리균이 생산하는 inulin fructotransferase(depolymerizing)을 이용, inulin을 분해하여 다량 생산한 다음 gel filtration 과정을 거쳐 순수 분리 정제하였다. 정제 DFAIII는 pH 2.5, 130℃에서 15분 가열 처리에 의해 약 35%의 분해율을 보이는 반면 sucrose는 완전히 분해되었으며, pH 5.5, 140℃ 처리 조건에서는 거의 분해되지 않는 매우 높은 열 안정성을 나타내었다. 또한 충치 유발의 중요 기준이 될 수 있는 S. mutans 증식 효과도 fructose와 sucrose는 물론이고 시판 올리고당보다도 훨씬 낮았다. 반면, Bifidus 균에 대한 증식 효과는 균주에 따라 다소의 차이는 있었으나 증식을 전혀 보이지 않았던 E. coli에 비해 뚜렷한 증식 촉진효과를 나타내었다. BL 배지에서의 Bifidus longum과 E. coli의 혼합 배양에 있어서도 Bifidus longum의 경우에서는 선택적으로 뚜렷한 증식 촉진 효과를 보였으나 E. coli의 증식은 오히려 억제됨을 확인하였다. 이상의 실험 결과를 종합 분석해 본 결과 DFAIII는 매우 우수한 생리 효과를 기대할 수 있는 감미료 소재중의 하나인 것으로 평가되었다. Some physical and physiological properties of di-D-fructofuranose dianhydrideIII(DFAIII), as a new sweetener, were investigated via in vitro experiments. The disaccharide was prepared by decomposing inulin with inulin fructotransferase(depolymerizing) from Arthrobacter sp. A-6. DFAIII had more excellent heat and acid stability than sucrose. This was one of the most desirable properties especially for the oligomer types of sweetener. DFAIII showed the least pH drop in the Streptococcus mutans culture, compared with the other saccharides examined. This indicates that the sugar will be fairly effective for prevenreas, E. coli did not show growth promotion in the DFAIII-containing medium. In the co-culture of Bifidus longum and E. coli in the BL medium, Bifidus longum had a selective growth while the growth of E. coli appeared rather to be inhibited.

알루미늄合金(A5052-0) 熔接部의 疲勞破壤擧動에 關한 實驗的 硏究

李龍福,元光浩 弘益大學校 1985 弘大論叢 Vol.17 No.2

This research deals with Aluminum-Alloy (A5052-0) weldments. In this research the following conclusions are obtained. 1. when the fatique crack in heat affected zone propagates to base metal zone, total life is long in the following order, base metal, unrestrained weld metal, restrained weld metal, and fatigue crack growth rate is low in the same stress intensity factor range in the following order, base metal, unrestrained weld metal, restrained weld metal. 2. when the fatigue crack in base metal zone propagates to heat affected zone, total fatigue life is long in the following order, restrained weld metal, unrestrained weld metal, base metal, and at first time crack growth rate on base metal is higher than in weld metal but lower at the middle of specimen. 3. In E.C.T. specimen and C.C.T. specimen residual stresses in weldments largely act on fatigue behavior and in E.C.T. specimen mechanical properties of bead zone extend total fatigue life.

SF7에 대한 部分 이온화 斷面積測定

김용복 공주대학교 사범대학 과학교육연구소 1994 과학교육연구 Vol.25 No.1

?? 電子충격 이온화는 二重焦點質量分析器의 Nier型의 이온원을 使用하여 처음 시발부터 180eV에 이르는 電子에너지의 函數로서 硏究되었다. 생성이온 ??, ??,??, ??, ??, ??그리고 ??에 대한 絶對部分 이온화 斷面積 函數들은 이온 軌道산출에 의하여 보충되고 개선된 實驗方法도 구하였다. 本實驗에서 測定된 값은 이 새로운 측정 方法의 정밀도와 신뢰도를 위하여 이전에 測定된 理論的 結果와 比較하였다.

Al 2024-T4 熔接部의 殘留應力이 疲勞破壞擧動에 미치는 影響

李龍福,金鐘鉉 弘益大學校 1986 弘大論叢 Vol.18 No.2

Fatigue fracture behaviors were investigated by using the TIG welded aluminum alloy such as high-strength Al2024-T4 which are widely used in aero-space industry. The fatigue crack propagation was closely examined in both from tensile residual stress region towards compressive residual stress region and from compressive residual stress region towards tensile residual stress region. The experimental results are summarized as follows: 1. In case of fatigue crack propagation from tensile residual stress region, the values predicted by the Forman equation were found to be exactly corresponded to the experimental values. 2. In case of fatigue crack propagation from compressive residual stress region, the Forman equation was found improper to apply directly, but the equation was found proper, if the stress ratio was modified to zero. 3. It was found that crack propagation speed at tensile residual stress region was greater in restrained welding than in unrestrained welding, While crack propagation speed at compressive residual stress region was the same, both restrained welding and unrestrained welding.