α-(Fe, Co)기 Nd - (Fe, Co) - B - Nb - Cu 초미세결정립합금의 자기특성에 미치는 Nd의 영향

조덕호(Duck-Ho Cho),조용수(Y. S. Cho),김택기(T. K. Kim),송민석(M. S. Song),김윤배(Y. B. Kim) 한국자기학회 1999 韓國磁氣學會誌 Vol.9 No.3

Magnetic properties and microstructure of nanocrystalline α-(Fe, Co)-based Nd-(Fe, Co)-B-Nb-Cu alloys have been investigated. Ndx(Fe_(0.9)Co_(0.1))_(90-x)B_6Nb₃Cu₁(x = 2, 3, 4, 5, 6) alloys prepared by rapid solidification process show amorphous phase except the one with x = 2. By a proper annealing, the amorphous phase in the alloy is changed to a nanocrystalline phase. It is confirmed that the nanocrystalline alloys are composed of α-(Fe, Co) and Nd₂(Fe, Co)₁₄B₁ phase. The optimally annealed Nd₃(Fe_(0.9)Co_(0.1))_(87)B_6Nb₃Cu₁ alloy shows the highest remanence of 1.55 T. The coercivity increases with the increase of Nd content. The maximum coercivity of 4.6 kOe is obtained from an optimally annealed Nd_6(Fe_(0.9)Co_(0.1))_(84)B_6Nb₃Cu₁ alloy, resulting in the maximum energy product of 10.6 MGOe.

Ga 첨가가 α-Fe기 Nd - Fe - B 합금의 자기특성에 미치는 영향

조덕호(Duck-Ho Cho),이병엽(Byung-Yeop Lee),조용수(Y. S. Cho) 한국자기학회 1997 韓國磁氣學會誌 Vol.7 No.1

The nanocrystalline Nd-Fe-B alloys with low Nd content were prepared by rapid solidification technique. The alloys consist of bothα-Fe as the main phase and Nd₂Fe₁₄B₁ as a secondary phase and have an ultrafine grain structure of about 30 ㎚. The addition of Ga in Nd₄Fe_(82)B_(10)Mo₃Cu₁ alloy increases remanence up to 1.29 T and improves squareness. The nanocrystalline Nd_5Fe_(81)B_(10)Mo₃Cu₁Ga₁ alloy has a volume fraction of Nd₂Fe₁₄B₁ phase of around 35% due to the increase of Nd content and shows an improved coercivity. The remanence, coercivity and energy product of optimally annealed nanocrystalline Nd_5Fe_(81)B_9Mo₃Cu₁Ga₁ alloy are 1.24 T, 257.4 ㎄/m (3.23 kOe), and 100.3 kJ/㎥(12.6 MGOe), respectively.

超高溫耐熱W合金의 燒結에 관한 硏究

趙德鎬 大田開放大學 1987 論文集 Vol.7 No.-

The most difficult process in making W-Ag alloy metals is to obtain the porous tungsten compacts of goof structure. Two fundamental properties needed in porous tungsten compacts are high mechanical strength and goof structure with linked porosities. Introducing the activated sintering process & manufacturing the porous tungsten compacts, the following results are obtained. (1) The propest sintering density in the porous tungsten compacts is 80%. (2) The rate of the closed porosities to the total porosities of the porous tungsten compacts is much influenced by the particle size distribution of raw powder. (3) By adding a very small amount of Ni at the low sintering temp. of 1300℃, the porous tungsten compacts with 80% sintering density were obtained. (4) The infiltration proceeds fastly as the infiltrating agent is melted, and the structure of the porous tungsten compacts nearly didn't change.

AISI304L Stainless 鋼의 應力腐蝕龜裂에 미치는 冷間加工의 影響

趙德鎬 大田開放大學 1986 論文集 Vol.5 No.-

The effect of cold working on the stress corrosion cracking (SCC) of AISI 304L stainless steel plate was studied. The SCC tests were carried out in boiling 42% MgCl_2 solution and the results were summarized as follows. 1. The effect of cold working on SCC susceptibility was remarkable, and the resistance to SCC showed maximum at 30% of cold work after solution treatment. 2. The fracture mode changed intergranular → transgranular → intergranular as the amount of cold work increased. 3. Fracture surface was observed to consist of two regions; a stress corrosion cracked region on the outside, and a mechanically fractured region in the center. 4. Virtually all specimens failed in the vapor phase approximately 0.5 - 1.0 cm above the liquid - vapor interface.

2000학년도 학기제 현장실습제도의 효과 분석 및 1999학년도의 분석결과와의 비교 연구 : 현장실습의 교육적인 가치 및 운영적인 측면을 중심으로 based on the educational value and the operational aspect

金相吉,趙德鎬,李相鎬,具本及 大田産業大學校 2001 한밭대학교 논문집 Vol.18 No.-

The main purpose of this study focuses on the analysis of the effectiveness of the sandwich education system by comparing the educational value and operational efficiency between the 1999 and 2000 school years. This study is based on questionnaires from 67 students of the Division of Advanced Materials Engineering at Han-Bat National University, 13 major field professors who guided the students, and 18 industrial personnel who trained the students during the program. Students participated in the field experience from the beginning of September, 2000 to the middle of December in the same year. They were surveyed in the beginning of 2001. The results of the analysis are compared to the ones which were surveyed in the end of 1999 school year. The first part of the question is related to educational values of the program and the second part of the question consists of the operational aspect of the program. The results of the 2000 years program has much improved compared to that of the 1999school year. Many of the negative views students showed in 1999 have turned positive ones in 2000.

학기제 현장실습제도(Sandwich System)의 보다 효율적인 운영 및 개선 방안 연구

김상길,조덕호,이상호 大田産業大學校 2000 한밭대학교 논문집 Vol.17 No.1

The main purpose of this paper is to study methodologies of more effective management and improvement of the sandwich system for the Division of Advanced Materials Engineering in the Taejon National University of Technology (TNUT) to provide the result of on-the-job experience based on the semester and to utilize selected elements of the program in the next semester and other colleges and universities. The study uses questionnaire methodology by developing twenty-four questions to investigate and analyze the issues and problems of the sandwich education system managed for the thirst time at TNUT. The study also tries to find out the ways of improvement of the program. Participants of the study are students, faculty members of the Division of Advanced Materials Engineering at TNUT and industrial staff members who were participated of the sandwich education program. The study shows that students are not satisfied with the management system of the program, especially the lack of preparation, orientation as well as the communication channel between the staff members of the University Specialization Team, administered the program and the students. However, participated faculty members and industrial staff members highly evaluated the whole process of the program in general. For the improvment of the program students want to have industrial experiment in the better working places, such as providing the good working condition, payment, and the major-rebated efficient program. The result of the study shows that student are not ignore the importance and the outcomes of the program and the on the job experience while they are in school, but they want to change some management systems of the program. Faculty members participated are agree on the management system of the program, but they think student are not fully understand the values of the program. Industrial staff members are most favorable and they want to participate to the program atwain, if they have another chance, but they do not want to pay students during the practicum.

학기제 현장실습제도의 교육적 가치 분석

김상길,조덕호,이상호,구본급 한밭대학교 생산융합기술연구소 2004 생산기반기술연구소 논문집 Vol.4 No.1

The main purpose of this study forcuses on the analysis of the educational value of the semester-based practicum system by comparing from the 1999 to the 2001 school years. This study is based on questionnaires from the student, faculty members and the industrial personnel who were participated to the practicum. The question is related with the educational value of the program, such as "I think that classroom learning is enriched through the program", "I think that the program is helpful to decide my future job", and so on. The results of the 2001 year program have shown much improvement compared to those of the 1999 and 2000 school years. Especially, many of the negative views students showed in 1999 have turned positive in 2001.

피아노후레임 제조기술에 관한 연구

이의길,최양진,조덕호 한밭대학교 산업과학기술연구소 1994 논문집 Vol.2 No.-

Effects of chemical composition, inoculation, shape of graphite and matrix structure upon the mechanical properties and damping capacity of cast iron were investigated. Tensile strength and Rockwell hardness of cast iron were increased by inoculation. The depth of chill and distortion for the manufactures were improved by shape of graphite and matrix structure. The damping capacity was attributable to the characteristic property of graphite.

참여주체간의 현장실습제도에 대한 인식차이 설문조사 연구

金相吉,李相鎬,趙德浩 한밭대학교 산업과학기술연구소 2001 논문집 Vol.5 No.-

The main purpose of this study is to investigate and analyze the perceptional differences between major participants for the Sandwich System. The participants of the study are students, faculty members for the Division of Advanced Materials Engineering in the Taejon National University of Technology(TNUT) and employers, taken part into the program for the second semester of 1999 school year. The study shows that students are not satisfied with the employers for their planning and preparation of the program, on the job program, their educational philosophy of the program, etc. But students are satisfied with the employer for their professional knowledge of the subject field, methodology of training, assessment for the students, and so on. Students are agreed on 7 out of 12 questions, but disagreed 5 items. Students are evaluated themselves in two ways. They said that they worked hard, kept time well, did assignments well. But they said that they did not have communication channels with their faculty members before the program, they were worried about accidents during the work, and others. This article pinpoints that faculty-members need to have good communications with their students in selecting the employer and placing the students. The paper also stresses the importance of administrative organization for the program in the university. The study suggests that the government has to amend the law and regulations for the betterment of the program.

소결온도와 산소분압이 MnZn Ferrite 의 자기적 특성에 미치는 영향

김택기,박용국,조덕호,허원도 대한금속재료학회(대한금속학회) 1990 대한금속·재료학회지 Vol.28 No.8

The effect of sintering temperature and oxygen partial pressure on the magnetic loss and permeability of MnZn ferrite has been studied. The lowest magnetic loss is obtained at the sintering temperature of around 1280℃ with oxygen partial pressure of 0.04 atm. Permeability increases with increasing sintering temperature, and decreases with oxygen partial pressure at a constant sintering temperature.