격자 불일치 GaAsP/GaAs와 GaAs/GaAsP/GaAs 이종 접합의 구조 및 전기적 특성

최영완 중앙대학교 기술과학연구소 1997 기술과학연구소 논문집 Vol.27 No.-

Structural and electrical characteristics of the GaAS?P?/GaAs and GaAs/GaA?P?/GaAs (x = 0.02, 0.05, 0.08, 0.16 and 0.32) hetero-epitaxial systems have been investigated using double crystal x-ray rocking curve (XRC) technique, optical beam induced current (OBIC) imaging, Nomarski micrograph, I-V-T, and C-V measurements. The rocking curve full width half maximum of the GaAS?P? epilayer increased sharply at x = 0.16 due to a decreased layer thickness and increased in-plane mismatch. The cross-hatched line density in the OBIC image and Nomarski micrograph increases as the lattice mismatch increases. The epilayer surface morphology is dependent of the layer thickness. The forward I-V characteristics of Au-GaAsP/GaAs and Au-GaAs/GaAsP/GaAs Schottky diodes showed an increased tunneling current for an increased lattice mismatch. ForGaAsP/GaAs structure with a higher phosphorus composition, Fermi level pinning caused by high density misfit dislocation was observed when the magnitude of in-plane mismatch greater than about 0.5%. This Fermi level pinning and the average spacing of misfit dislocation measured by XRC were consistent with Woodall's model. Au-GaAs/GaAsP/GaAs Schottky diodes show an excess current at the low temperature and high field range which, we believe, is due to defect related tunneling.

분산 시스템에서 경험적 방법을 이용한 동적 화일 할당 알고니즘

최재식,구용완 수원대학교 기초과학연구소 1993 基礎科學論文集 Vol.2 No.-

A lot of researches have been conducted for the optimal distribution of files among the nodes in distributed system. The purpose of those researches was to increase system reliability and to decrease read access cost. This paper studied a file allocation algorithm which finds file replication and placement for maximizing file accessibility with minimun cast. The key method on this study was as to how effectively access to a created file that was depended on the timing and placing to each node. We proposed an optimal file allocation algorithm while considering read/write access number, communication cost and file size. Then, we presented an algorithm for deciding allocation time and placing minmum preallocation file access cost and for dynamic file allocation algorithm with O(N^4) time complexity.

PZT께 압전 세라믹스의 제조 및 기계적 특성에 관한 연구

崔永根,權鍾完 慶一大學校 1993 論文集 Vol.9 No.1

Densification behavior, microstructural evolution and mechanical properties of hot-pressed specimens using PZT ceramics with PbO additive were studied, and bulk density, microstructure, mechanical properties were investigated for sintering time. Fracture toughness of the spections containing 1mol% PbO was increased as the hot-pressing temperature up to 1080℃ and maximum value was 1.60MN/m??, while fracture toughness of the specimens containing 2mol% PbO was decreased. The enhanced fracture toughness by PbO is probably due to the crack deflection along the boundaries of the elongated grains. Vicker's hardness of the specimens was in the range of 270-320Kgf/mm² and was decreased due to the incrasing of pore according to PbO addition. As the sintering time becomes longer, fracture toughness was gradually decreased for the the increasing of grain size and vicker's hardness was shown the linear increasing lue to increase of density.

연령과 골소주 특성의 골량에 대한 연관관계

최동훈,송영한,윤영남,이완,이병도 대한구강악안면방사선학회 2006 Imaging Science in Dentistry Vol.36 No.2

Purpose : Bony strength is dependent on bone mass and bony structure. So this study was designed to investigate the relationship between the bone mass and bony trabecular characteristics. Subjects and Methods : Study subjects were 51 females (average age 68.6 years) and 20 males (average age 66.4 years). Bone mineral density (BMD, grams/cm²) of proximal femur was measured by a dual energy X-ray absorptiometry (DEXA). Regions of interest (ROIs) were selected from the digitized radiographs of proximal femur. A customized computer program processed morphologic operations (MO) of ROIs. 44 skeletal variables of MO were calculated from ROIs on the Ward’s triangle and greater trochanter of femur. WHO BMD classes were predicted by MO variables of the same ROI. Classification and Regression Tree analysis was used for calculating weighted kappa values, sensitivity and specificity of MO. Results : The discriminating factors of morphologic operation were branch point, branch point [per cm sq]. Age also played important role in distinguishing osteoporotic classes. The sensitivity of MO at Ward’s triangle and Greater Trochanter was 91.8%, 65.6%, respectively. The specificity of MO was 100% at Ward’s triangle and Greater Trochanter. Conclusion : Bony trabecular characteristics obtained using radiological bone morphometric analysis seem to be related to bone mass.

중·고 육상선수들의 25m 달리기, 반응시간 그리고 동작시간과의 관계

최종환,김태완,최종수,이영희,장민영 忠北大學校 平生體育硏究所 1996 平生體育硏究所 論文集 Vol.8 No.-

This study was to understand the neuromuscular coordination, analyzing the relationship among 25m dash, simple reaction time (SRT) and choice reaction time (CRT) of whole body and finger, and movement time (MT) of middle and high school sprinters (N=24). There were significant relationships among simple reaction time (SRT), choice reaction time (CRT), movement time (MT), and interval(Int) lap times of middle and high school sprinters: the faster SRT, the faster MT, Int 1,2,3,4,5, and 25m running time for all sprinters; The faster CRT, the faster Int 1,2,3,4,5, and 25m running time of all sprinters. Also, same to SRT and CRT by hand(s). While sprinters' MT in high school was significantly related to Int 1,2,3,4,5, and 25m running time, sprinters' MT in middle school was not related to any Int 1,2,3,4,5, and 25m running time. In addition, while 25m running time of high school sprinters was predicted by Int 1(RT+MT), in turn, Int 3,2, gender, SRT and CRT, 25m running time of middle school sprinters was predicted by Int 3, in turn, Int 1(RT+MT), and 2. Even though male sprinters in high school showed faster SRT and CRT female sprinters in lab, male sprinters were not significantly better than female sprinters on reaction time (RT) during starting phase. There was gender difference on each running time of Int 2,3, and 4 (5-15m), but not on RTs

Methotrexate 치료를 받고 있는 활동성 류마티스 관절염 환자에서 etanercept의 유효성과 안전성에 관한 연구

최병렬,강태영,정청일,이혜순,엄완식,김태환,전재범,유대현,배상철 대한내과학회 2004 대한내과학회지 Vol.66 No.5

목적 : 류마티스 관절염을 앓고 있는 한국인 중에 기존 DMARDs로 치료 실패하였고, 고정용량의 MTX를 복용하고 있는 환자들에 있어서 etanercept의 유효성과 안전성을 평가하고자 하였다. 방법 : 기존 DMARDs로 치료 실패한 활동성 류마티스 관절염 환자 76명을 대상으로 하여 단일군, 공개시험을 하였다. 대상 환자들은 고정용량의 MTX를 복용하면서 etanercept 25 mg을 1주일에 두 번 피하 주사하였으며 12주간 투여하였다. 유효성은 ACR 20, ACR 50,조조강직 시간으로 평가하였고, 약제의 안전성은 이상반응 등으로 평가하였다. 결과 : 대상 환자는 총 76명으로 평균 연령은 45.2세, 남자 5명, 여자 71명이었다. 84.4%인 54명이 12주째에 ACR 20을 만족하였고, 53.1%인 34명이 12주째에 ACR 50을 만족하였다. 조조 강직 시간은 치료 전 203.3분에서 치료 12주째 42.6분을 평균 74.5% 호전되었다. 가장 흔한 이상반응은 주사부위 반응이었다. 이외에도 상기도 감염, 오심, 안면부종 등이 발생하였으나 심각한 부작용은 없었다. 결론 : etanercept는 효과적이고, 안전한 류마티스 관절염 치료 방법이며 특히 MTX치료에도 불구하고 활동성인 류마티스 관절염에 기대되는 치료라고 할 수 있다. Background : This study was performed to investigate the efficacy and safety of etanercept in active rheumatoid arthritis patients with stable dose of methotrexate in Korean. Methods : In a 12 week, single arm, open trial, we assigned 76 patients with active rheumatoid arthritis who had an inadequate response to disease-modifying antirheumatic drugs. Patients received twice-weekly subcutaneous injections of etanercept 25 ㎎ while containing to receive methotrexate at a stable dose of 7.5~25 ㎎ per week. The clinical response was defined as the percent improvement in disease activity according to the criteria of the American Collage of Rheumatology (ACR) at 12 weeks. Results : Etanrecept led to significant improvements in disease activity and was safe and well tolerated. At 12 week, 84.4% of the patients receiving 25 ㎎ of etanercept achieved a 20% ACR response, and 53.1% of those receiving etanercept achieved a 50% ACR response. The most common adverse event was injection-site reaction. Other advanse events were upper respiratory infection, nausea, and facial edema, but there were no serious adverse events associated with etanercept. Conclusion : In active rheumatoid arthritis patients, etanercept was safe, well tolerated, and provided rapid clinical improvements.

폴리에스테르 모르타르의 경화수축

최낙운,김완기,조영국,소양섭 대한건축학회 2003 대한건축학회 학술발표대회 논문집 - 계획계/구조계 Vol.23 No.2

The setting shrinkage behavior in polyester mortars with two-phase shrinkage reducing agent(SRA) was observed at the ambient temperature. Polyester mortars were prepared with various styrene contents and two-phase shrinkage reducing agent(SRA) contents. The length change and exotherm temperature of polyester mortars were continuously monitored by a noncontact-type automatic length change measuring apparatus and a thermocouple embedded respectively. Low-shrinkage or non-shrinkage of polyester mortars should be accomplished by adjusting styrene content and SRA content.

직업적 디메틸아세트아미드(Dimethylacetamide) 노출에 의해 집단적으로 발생한 독성간염

최태성,우극현,김진석,박완섭,함정오,정상재,유재영 대한산업의학회 2001 대한직업환경의학회지 Vol.13 No.2

목적 : DMAC에 노출된 후 집단적으로 발생한 독성 간염 7례보고. 방법 : 2000년 2월 신설된 스판덱스 섬유제조 공장에 근무하는 생산직 근로자 178명중 2000년 2월 부터 8월까지 7명이 간장질환이 발생하였다. 환례들의 나이는 23∼47세였고, 남자 5명, 여자 2명이었다. 이들에 대해 혈액검사, 간 초음파 검사 등의 임상검사와 작업장 조사를 실시하였다. 결과 : 근무 부서는 중합 1명, 방사 1명, 권취 4명, 그리고 포장 1명이며 평균근무기간은 10주였다. 주 호소 증상은 심한 피로감, 어지럼증 및 황달이었고, 검사실 소견상 독성간염의 소견을 보였다. A, B 및 C형 간염 표지자 검사는 모두 음성이었고, 간초음파 소견상 특이 소견이 없었다. 문진 상 알코올 성 간염을 일으킬 정도의 음주력이나 최근 약물 복용력을 가지고 있는 환례는 없었다. 입원 후 보존적인 치료로 모두 급속히 호전되었다. 초기에 발생했던 환례에서 퇴원후 DMAC에 재 노출되어 독성 간염이 재발되었다. 이후 모든 환례들은 퇴원 후 DMAC 비노출 부서로 전환하였고, 퇴원후 지속적인 추적검사에서 간 효소 수치가 완전히 정상화되었고, 정상화되는 기간은 1∼2개월 정도 소요되었다. 결론 : 환례들의 임상증상, 검사결파, 노출력 및 과거력상 DMAC에 의한 독성간염으로 추정된다. Dimethylacetamide is widely used in the production of plasics, resins, synthetic fibers, and gums and in purification and crystallization processes. Inhalation of the vapor or skin absorption of the liquid of dimethylacetamide (DMAC) can cause liver damage. Toxic hepatitis possibly attributable to DMAC exposure occurred in seven works among 178 employees who had worked on a new spandex-fiber production line. A large amount of DMAC is used as a spinning solvent for synthetic fibers in the factory. The patients were aged 23-47 years old and composed of five males and two females. They were involved in the process of polymerization(1 patient), spinning(1), take-up(4) and packaging(1). The mean duration of exposure was 10 weeks. They experienced fatigue, dizziness and jaundice. The patients showed elavated total bilirubln, alanlne aminotransferase (ALT), and aspartate aminotransferase (AST) levels. The serologic test for viral hepatitis A, B and C were negative, as were the abdominal ultrasonographic scans. Based on the presumptive diagnosis of DMAC-induced toxic hepatitis, they were removed from the workplaces. One or two months after removal from the work, the transaminase levels returned to normal. The patients had no history of significant alcohol use, blood transfusion, recent medication, and drug abuse. As a result, authors could not find any attributable cause of toxic hepatitis but the toxicity by DMAC exposure.

기능성 소화불량증에서 증상에 따른 고형식의 반위배출시간의 차이

김영호,이풍렬,성인경,손희정,김재준,고광철,백승운,이종철,최규완 大韓消化器病學會 1998 大韓消化器病學會誌 Vol.32 No.3

철봉 내리기 공중 동작의 운동학적 분석(I)

최지영,김용이,진영완 한국운동역학회 2002 한국운동역학회지 Vol.12 No.2

본 연구는 철봉운동에서 기본이 되는 동작인 몸펴 한번 뒤돌아 내리기 동작을 단계적으로 분석한 후, 이를 토대로 하여 현재 시합상황 중 가장 널리 사용되는 응용동작인 몸펴 두 번 뒤돌아 내리기 동작과 몸펴 두 번 뒤돌며 한번 비틀어 내리기 동작의 운동학적 분석을 수행하여 개개분절 간의 상호작용을 해부학적 3차원 각운동과 각속도로 설명하고 이해할 수 있는 운동학적 자료를 제시하는데 있다. 피험자들은 현재 K대학교에 재학중이며 대학 대표선수인 남자 기계체조 선수 7명을 선정하였으며, 연구에 사용된 인체의 모델은 Zatsiorsky와 Seluyanov(1983, 1985)이 사용한 16개의 분절로 이루어진 인체의 모델을 사용하였다. 신체무게중심이 이동방향을 설명할 수 있는 투사각도 및 투사속도는 공중동작의 회전수가 증가할수록 신체무게중심이 투사되는 각도가 증가되며, 이렇게 증가된 신체무게중심의 투사각도는 신체무게중심의 최고점을 증가시키는 경향을 보였다. 3차원 투사속도를 살펴본 결과 Z방향(수직방향)은 공중돌기 회전수가 증가할수록 증가하는 경향이 나타났으나, 운동진행 방향인 Y방향 속도와 좌우측 기울기를 설명할 수 있는 X방향 속도에서는 의미 있는 차이를 보이지 않았다. 철봉 내리기 공중동작에서의 신체분절 및 각도 변화도 중요하지만 각운동량을 만들어내기 위한 동작준비구간의 각도 변화가 더욱더 중요하다고 할 수 있다. 즉, 상체가 철봉 아래 봉과 수직될 때부터 릴리즈 순간까지의 각도 변화에 주목해야 하는 데, 회전수가 증가할수록, 어깨관절 각도와 엉덩관절 각도 변화가 두드러지게 나타나 준비구간의 추기기 동작(Whip swing)의 주된 관절로 작용을 한다. 관성좌표계에 대한 상체의 움직임을 나타내는 3차원 방향의 각도 즉, 뒤돌기(somersault)각도, 틀기(twist)각도 그리고 기울기(tilt)각도로 설명이 되는데, 본 연구의 결과 릴리즈시 뒤돌기 각은 세가지 내리기 동작 유형에 따라 평균 57,7도, 38.8도 그리고 39.7도로 나타났으며, 기울기 각은 평균 -1.5도, -5.4도 그리고 -8.4도로 유의한 차이를 보이고 있으며, 틀기각도는 평균 13.4도, 10.6도 그리고 23.3도로 몸펴 두번 뒤돌며 한번 비틀어 내리기 경우 가장 큰 수치를 나타냈다. The purpose of this study was to investigate the relations between the segments of the body, the three dimensional anatomical angle and the angular velocity of the air born phase and understand the control mechanism of the high-bar movement, the somersault, the double somersault, the double somersault with full twist. For this study seven well trained university gymnastic volunteered, Zatsiorky and Seluyanov(1983, 1985)' sixteen segment system anatomical model was used for this study. For the movement analysis three dimensional cinematographical method(Arial Performance Analysis System : APAS) was used and for the calculation of the kinematic variables a self developed program was used with the LabVIEW 5.1 graphical profromming(Johnson, 1999) program. By using Eular's equations the three dimensional anatomical Cardan angles of the joint and angular velocity were defined. 1. As the rotation of the body increased in the air born phase the projection angle of the CM of the total increased, this resulted the increased of the max hight of the CM. 2. In three dimensional angular velocity the Z axis(vertical direction) projection angular velocity increased as the rotation of the body increased in the airborn phase, but the Y axis and the X axis projection angular velocity did not show significant differences. 3. As the rotation of the body increased in the air born phase the angular movement of the shoulder and the hip showed significant change. These movement act as the starter in the preparation phase. 4. The somersault angle, the twist angle, the tilt angle of the upper body related to the global reference frame in the releas phase the average somersault angle of the three types of high-bar movement was 57.7˚ , 38.8˚ , 39.7˚ , the average tilt angle was -1.5˚ , -5.4˚ , -8.4˚ , the average twist angle was 13.4˚ , 10.6˚ , 23.3˚ . This result showed that the somersault with full twist had the largest movement.