DCA-MOD 법에 의한 High $J_c$ YBCO 박막의 제조

김병주,김혜진,이금영,이종범,김호진,이희균,홍계원,Kim, Byeong-Joo,Kim, Hye-Jin,Yi, Keum-Young,Lee, Jong-Beum,Kim, Ho-Jin,Lee, Hee-Gyoun,Hong, Gye-Won 한국초전도학회 2006 Progress in superconductivity Vol.8 No.1

High $J_c\;YBa_2Cu_3O_x$ superconducting films were fabricated by MOD method using fluorine-free dichloroacetic acid(DCA) as chelating solvent for preparing precursor solution. Coating solutions were prepared by dissolving Y-, Ba- and Cu-acetates in DCA solvent followed by drying in rota vapor to obtain the blue gel that is diluted in methanol and 2-methoxyethanol for adjusting the cation concentration. DCA-MOD precursor solution was coated on a single crystal(001) $LaAlO_3(LAO)$ substrate by a dip coating method with a speed of 25 mm/min. Coated films were calcined at lower temperature up to $500^{\circ}C$ in flowing oxygen atmosphere with a 7.2% humidity. Conversion heat treatment was performed at various temperatures of $780{\sim}810^{\circ}C$ for 2 h in flowing Ar gas containing 1000 ppm oxygen with a humidity of 9.45%. SEM observations showed that films have very dense microstructures for the films prepared at the temperature higher than $800^{\circ}C$ regardless of diluting solvent; methanol or 2-methoxyethanol. X-ray diffraction analysis showed that YBCO grains grew with a (001) preferred orientation. A High critical current density($J_c$) of 1.28 $MA/cm^2$(@77 K and self-field) was obtained id. the YBCO film prepared using 2-methoxyethanol as a solvent.

DCA-MOD 방법으로 제조된 YBCO 박막의 미세조직에 미치는 열처리 효과

김병주,김혜진,조한우,유석구,유정희,이희균,홍계원,Kim, Byeong-Joo,Kim, Hye-Jin,Cho, Han-Woo,Yu, Seok-Koo,Ryu, Jung-Hee,Lee, Hee-Gyoun,Hong, Gye-Won 한국초전도학회 2007 Progress in superconductivity Vol.9 No.1

[ $YBa_2Cu_3O_{7-{\delta}}$ ] films have been prepared on $LaAlO_3$ (100) single-crystal substrates by a metalorganic deposition using dichloroacetate precursors (DCA-MOD). Calcination conditions were varied in order to optimize the microstructure and the superconducting properties of YBCO film. Coated films were calcined at various temperatures ranging from $400{\sim}700^{\circ}C$ in flowing humid oxygen atmosphere. Ramping rate to calcination tempertures was $2.22^{\circ}C/min$. Conversion heat treatment was performed at $800^{\circ}C$ for 2 h in flowing Ar gas containing 1000 ppm oxygen with a humidity of 9.45%. Observations of surface and cross sectional SEM microstructure showed that the particle size in the calcined film increased in the range of 100-200 nm with heating rate and the calcination temperature. SEM EDS analysis showed that 13 a/o of chlorine was contained in the calcined film. It was also observed that the porosity increased with the heating rate and temperature. Porous microstructure was developed when YBCO films were prepared using porous calcined film. Dense microstructure and high $J_c$ over $1\;MA/cm^2$ was obtained when calcination was carried out at the temperature of $500^{\circ}C$ with a heating rate of $2.22^{\circ}C/min$.

사전 원심성 운동이 운동 유발 근 손상에 미치는 효과

김병주,임영은,윤세원,박승규,김태열,Kim, Byoung-Ju,Lim, Young-Eun,Yoon, Se-Won,Park, Seung-Kyu,Kim, Tae-Youl 대한물리치료학회 2008 대한물리치료학회지 Vol.20 No.1

Purpose: This study examined the effects of pre-eccentric exercise to the quadriceps for the prevention of delayed onset muscle soreness (DOMS) and recovery of muscular function, depending on the training intensities. Methods: Subjects were divided into one of three groups that control group, a low intensity eccentric exercise group (LIEE group) and a high intensity eccentric exercise group (HIEE group). Subjects who underwent pre-eccentric exercise undertook exercise at an intensity of 25% and 75% of maximal voluntary contractions, respectively. After undertaking pre-eccentric exercise for eight weeks, eccentric exercise was applied again to induce DOMS. Measurements were conducted to examine pain and muscular function changes before, immediately after, after the induction of DOMS, and at the first, third, fifth and seventh days after the induction of DOMS. Results: Subjects who underwent pre-eccentric exercise showed a significant difference from the control group for the changes in the visual analogue scale (VAS) pain threshold, pressure pain threshold and muscle thickness by isometric contraction from measuring DOMS, and in particular, pain threshold by isometric contraction had remarkable effect in the LIEE group of subjects. For the change of the root mean square values using mechanomyography (MMG) as the measurement of muscular function recovery, subjects who had undertaken pre-eccentric exercise group showed a significant difference as compared to the control group. Conclusion: Pre-eccentric exercise was very effective in preventing and recovering delayed onset muscle soreness and was helpful to prevent and recover from decreased muscular function. The difference based on the intensity of exercise was not great, but it was more effective in the low intensity eccentric exercise group of subjects. Therefore, it can be considered that pre-eccentric exercise has a high application value as a physical therapy intervention for prevention and rehabilitation of sports injuries.

사서교사의 역할에 대한 인식연구

김병주,Kim Byong Ju 한국문헌정보학회 1989 한국문헌정보학회지 Vol.17 No.-

The school library plays very important and central role for the fullfillment of educational objective in the process of implementing the school curriculum. And the media specialist known as teacher-librarian is. primarily responsible for the successful operation and effective management of the media center. It is true that effectiveness of the school library depends greatly on the cooperative coordination among teacher-librarian, teacher and principal in addition to the strong support and effective supervision of school district authority, specifically, supervisor of school library program. The successful program therefore is influenced by their perception of the teacher-librarian's role. The purpose of this study was to investigate the teacher-librarian's. educational role perceived by teacher-librarian, teacher, principal and school district supervisor. A standard task model describing both the management and educational functions and expectations of teacher-librarian was proposed after studying the relevant current standards of four countries. Serveral hypotheses were made regarding role perception and a survey instrument was designed based on this proposed task model and the results of the literature review to validate the hypotheses. The questionnaires were mailed out and the returned questionaires were analyzed by SPSS computer routine. The major findings are summarized as follows: 1) There was difference of the role perception among teacher-librarian, teacher, principal and district supervisor at the significance level of p<0.001 for both management and educational functions of teacher­librarian. The mean score of the teacher-librarian was highest among four groups and the score for the educational function tasks were lower than that of management function tasks. 2) The positive correlation exists at the significance level of p<0.001 between the role perception and the attitude toward changing social trends such as acceptance of new technology, need for better communication and information. 3) The positive correlation exists at the significance level of p<0.001 between the role perception and the view on the curriculum and teaching method.

비등유로의 압력강하 요동특성

김병주,신광섭,Kim, B.J.,Shin, K.S. 대한설비공학회 1995 설비공학 논문집 Vol.7 No.1

Characteristics of pressure-drop oscillations(PDO) in a boiling channel were studied numerically and compared with experimental data. Effects of initial and boundary conditions on PDO were investigated in terms of oscillation period and amplitude. The period and amplitude of PDO increased with increasing of the compressible volume in the surge tank and the heat input. PDO occurred within the specific range of the fluid temperature, at which oscillation period and amplitude diminished rapidly with the increase of the fluid temperature. The increase of the loss coefficient in fluid supply line resulted in slightly longer oscillation period and larger amplitude. Numerical results showed good agreement with the experimental data.

뇌동맥류 파열 환자의 수술후 인지기능과 기억력장애에 관한 연구

김병주,최창화,김대진,Kim, Byung Joo,Choi, Chang Hwa,Kim, Dae Jin 대한신경외과학회 2001 Journal of Korean neurosurgical society Vol.30 No.7

Objectives : The mortality rate of subarachnoid hemorrhage(SAH) has been reduced recently due to refinement of microsurgical technique and improved perioperative management. Also, many survivors of SAH show excellent neurological recoveries. However, we found that a high proportion of the survivors do not fully regain their premorbid status in cognitive and memory function. Object of this study is to evaluate which factors might influence on cognitive and memory impairment in ruptured aneurysmal SAH patients. Methods : In this prospective study, a series of 66 patients with aneurysmal subarachnoid hemorrhage(SAH) from 1996 to 1998, most of whom had a "good" or "fair" neurological outcome, were assessed with various tests of cognition and memory function. All patients underwent clipping operation by pterional approach. Right side approach was performed in 16 case and left 21 cases. K-WAIS(Korean-Wechsler Adult Intelligence Scale) was used as method of cognition and memory function test. The time interval between SAH and assessment varied between 4 months and 8 months, averaging 6.2 months. Statistical analyses were carried out for each test score to see whether aneurysm site(A-com : non A-com), route of approach, age and sex, vasospasm, Hunt-Hess grade and Fisher CT group at admission, Glasgow Outcome Scale(GOS) at discharge affect cognitive and memory function. Results : Aneurysm site was not shown to be associated with performance on any test, and the initial grade (Hunt-Hess grade, Fisher CT group) of SAH and vasospasm had only minimal predictive values. The grade at discharge( GOS) was proved to be the best predictor of impairment of cognition and memory function within 1 year after operation. Conclusion : The authors conclude that the diffuse effects of SAH are more important than focal neuropathology in relation to cognitive impairment in this group of patients.

점진적인 주성분분석기법을 이용한 고차원 자료의 특징 추출

김병주,Kim Byung-Joo 한국정보통신학회 2004 한국정보통신학회논문지 Vol.8 No.7

고차원 자료를 효율적으로 처리하기 위해서는 특징 추출 기법이 필요하다. 주성분분석 방법은 대표적인 특징추출 방법이지만 학습 자료의 차원이 큰 경우에는 고유공간을 계산하기 위해 많은 기억공간과 계산량을 필요로 한다. 본 논문에서는 고차원 자료의 특징 추출을 위해 점진적인 주성분분석 방법을 사용한다. 제안한 방법에 대해 신경망에서 점진적인 주성분분석을 하는 대표적인 방법인 APEX모델과 실험을 통해 비교해 본 결과 제안된 방법이 APEX 모델 보다 성능이 우수함을 나타내었다. High dimensional data requires efficient feature extraction techliques. Though PCA(Principal Component Analysis) is a famous feature extraction method it requires huge memory space and computational cost is high. In this paper we use incremental PCA for feature extraction on high dimensional data. Through experiment we show that proposed method is superior to APEX model.

이동 로봇을 위한 온라인 동시 지도작성 및 자가 위치 추적 알고리즘

김병주,Kim, Byung-Joo 한국데이터정보과학회 2011 한국데이터정보과학회지 Vol.22 No.6

본 연구에서는 실제 환경에 적용 가능한 지능형 자율 이동 방법을 개발하기 위해 위치정보를 사용하지 않고 지도 작성이 가능한 지능형 이동 알고리즘을 제안한다. 제안한 알고리즘은 온라인으로 동작하면서 위치 정보를 사용하지 않고 지도 작성이 가능 할 뿐 아니라 현실 세계에 적용 가능하기 위해 많은 계산량을 요구하지도 않는다. 이는 이동 로봇의 실세계 주행과 같은 대용량의 이미지 처리가 필요한 경우에는 매우 유용하게 사용될 수 있다. 토이 자료와 대용량 자료에 대해 제안한 알고리즘을 적용한 결과 기존의 방법에 비해 적은 메모리와 새로운 입력에 대해 고유공간을 새로 계산하지 않아도 되어 로봇의 현실세계의 주행에도 문제가 없는 것으로 판단되었다. In this paper we propose an intelligent navigation algorithm for real world problem which can build a map without localization. Proposed algorithm operates online and furthermore does not require many memories for applying real world problem. After applying proposed algorithm to toy and huge data set, it does not require to calculate a whole eigenspace and need less memory compared to existing algorithm. Thus we can obtain that proposed algorithm is suitable for real world mobile navigation algorithm.

복셀 맵을 이용한 단백질 표면 원자의 발견 알고리즘

김병주,김구진,성준경,Kim, Byung-Joo,Kim, Ku-Jin,Seong, Joon-Kyung 한국정보처리학회 2012 정보처리학회논문지 A Vol.19 No.2

본 논문에서는 단백질 분자로부터 표면 원자를 효율적으로 발견하는 알고리즘을 제안한다. 표면 원자란, 주어진 probe solvent $P$가 단백질 분자와 충돌하지 않고 접한다고 가정할 때, $P$와 접할 수 있는 원자의 집합을 의미한다. 단백질 분자를 구성하는 원자들은 반데르바스 반경을 갖는 구의 집합으로 표현되며, probe solvent 역시 구로 대응된다. $P$의 반경에 대해 분자의 오프셋 곡면을 구하여 표면 원자를 발견하는 알고리즘을 제안한다. 제안된 알고리즘은 각 구의 오프셋 곡면에 대해 복셀 맵(voxel map)을 구성하여 효율적으로 분자의 오프셋 곡면을 구하며, GPU (graphic processor unit)를 활용한 병렬처리를 수행하여 최대 6,412개의 원자를 갖는 분자에 대해 42.87 millisecond 내에 표면 원자를 발견한다. In this paper, we propose an efficient method to extract surface atoms from a protein molecule. Surface atoms are defined as a set of atoms who can contact given probe solvent $P$, where $P$ does not collide with the molecule. The atoms contained in the molecule are represented as a set of spheres with van der Waals radii. The probe solvent also is represented as a sphere. We propose a method to extract the surface atoms by computing the offset surface of the molecule with respect to the radius of $P$. For efficient computation of the offset surface of a molecule, a voxel map is constructed for the offset surfaces of the spheres. Based on GPU (graphic processor unit) acceleration, a data parallel algorithm is used to extract the surface atoms in 42.87 milliseconds for the molecule containing up to 6,412 atoms.

특집 - 대학 재정문제 - 대학재정 효율화

김병주,Kim, Byeong-Ju 한국대학교육협의회 2012 大學敎育 Vol.175 No.-