Fe-31% Ni 합금에 있어서 Ausformed martensite 의 기계적 성질

김학신,최종술,양훈영 대한금속재료학회(대한금속학회) 1982 대한금속·재료학회지 Vol.20 No.1

Austenitid Fe-31%Ni alloy was prepared by induction melting, and then effects of prior deformation degree on the susformed martensite were investigated. The results obtained in this study are as follows. 1. Although iron-nickel alloy contains little carbon content, the ausformed martensite of this alloy showed remarkable increase ih tensile strength. 2. The strengthening of ausformed martensite in this alloy was considered to be attributed to a direct transfer of lattice defects such as tangled and sessile dislocation formed in deformed austenite to martensite phase during martensitic transformation, and about 40 pct of work-hardening in prior austenite was introduced to the strength of martensite phase in susformed martensitic structure. 3. The elongation of austenite was decreased with increasing deformation degree. However the elongation of susformed martensite showed a nearly constant value, independent of austenite deformation degree.

低周波誘導爐의 設置 및 操業에 對한 考察

金學信 全北大學校 1970 論文集 Vol.12 No.-

The quality improvement of cast irons and non-ferrous metal alloys can be achieved by more Low Frequency Induction Furnace than cupola operation. Owing to developing of machine industry in Korea, low quality cast irons and non-ferrous metal alloys to be produced by means of cupola and crucible melting furnace are to decrease, while it is inclined for many country, especialy Korea to set up Low Frequency Induction Furnace. Therefore, the author attempted, in this paper, a consideration on its construction and operation. It is expected that this paper gives many suggestions for Field Engineers to exploit its operation.

게이지용 스텐레스강의 충격인성과 내마모성에 미치는 열처리의 영향

金學信,李圭福,李宗炫,金相泰 전북대학교 전자산업개발연구소 1990 전자산업연구 Vol.1 No.-

In this study, the effect of heat treatments on the mechanical properties was investigated in martensitic stainless steel for gauge. The experimental results showed that the hardness was decreased but the impact value was increased with increasing tempering temperature after solution teatment. Therefore, in the view-point of the hardness and impact toughness, it is better to temper at low temperature, 250℃. In isothermal transformation treatment, the hardness in martempering treatment was higher, but the impact value was lower than in marquenching treatment. The wear resistance was propor-tional to the increase in hardness and the wear mechanism was changed from mechanical abrasive wear to adhesive wear with increasing speed change. The wear loss was increased almost linearly with increasing load and the wear resistance in martempering treatment was better than any other heat treatments.

Pb-Sb 合金의 時效 析出에 對한 考察

金學信 전북대학교 공업기술연구소 1978 工學硏究 Vol.8 No.-

The ageing effects and mechanisms taking place in the precipitation process of quenched leadantimony alloys were investigated by measuring and considering the variations in electrical resistivity and hardness. The results obtained by ageing precipitation are as follows: 1.The main mechanism of precipitation seems to be one of nucleation and growth of precipitation which give rise to large plate-shaped precipitates of pure antimony. 2.The ageing takes place faster when the solute content, antimony content, is higher. The lower ageing temperature is, the higher the hardness attained is. 3.A low--temperature treatment just after quenching leads to a greater process rate, that can be explatined in terms of the potin defect theory. In this particular case for the temperature of -10℃, it can be seen that ageing takes place especially faster. 4.The influences of a plastic deformation just after quenching delays kinetic due to an increase in the incubation period. 5.With small bismuth and tin additions, the ageing precipitation of pd-sb alloys decreased, while it is greatly accelerated with small arsenic additions.

나물용 콩 파종기에 따른 콩나물의 하배축 및 생장특성 차이

김학신,김경호,김홍식,이용호,정승근 韓國作物學會 2006 한국작물학회지 Vol.51 No.7

본 연구는 나물용 콩의 파종기가 콩나물 원료콩의 배축신장성과 콩나물 생장 및 수율에 미치는 영향을 구명함으로써 양질 콩나물 품종육성과 재배기술 확립을 위한 기초 자료를 얻고자 2000~2001 년에 호남농업연구소 전작시험포장에서 파종기를 달리하여 생산된 원료콩을 이용하여 실험실과 콩나물 간이검정실에서 시험을 수행하였던 결과를 요약하면 다음과 같다. 1. 재배온도별 콩나물의 배축신장성은 재배온도가 높을수록 빨랐으며, 재배일수가 길어질수록 그 차이가 컸다. 2. 콩나물의 배축장과 근장은 연차간에 차이가 있었으며 7월 5일 파종이 5월 25일과 6월 15일 파종보다 길었고, 배축굵기는 도레미콩이 가장 굵었으며 한남콩이 가늘었다. 전장은 파종기가 늦어질수록 길어졌고 은하콩이 가장 길었으며, 다원콩이 가장 짧았다. 3. 콩나물의 부패립율과 불완전발아립율은 파종기가 늦어지면서 감소하는 경향이었다. 부패립율은 다원콩이 가장 낮았고 소명콩이 가장 높았으며 불완전발아립율은 풍산나물콩이 가장 낮았고 한남콩이 가장 높았다. 4. 콩나물 수율은 2001년에 생산된 종실에서 더 높았고 파종기가 늦어질수록 증가하였으며, 은하콩과 도레미콩이 높았고 파종기에 따른 콩나물 수율의 변이가 적고 안정적인 품종은 풍산나물콩과 소명콩이었다. 5. 콩나물 수율과 제형질과의 관계는 종실의 수분흡수율이 낮고 치상 1일과 4일후의 발아율이 높은 것이 콩나물 수율이 높았으며, 콩나물 수율과 배축장, 근장 및 개체당 생중과는 정의 상관이었다. This study was conducted to investigate the effects of sowing date on soybean-sprout growth characters and for improving cultural techniques to produce high quality soybean-sprout. Six sprout-soybean cultivars were planted on three sowing dates in 2000 and 2001. The growth of hypocotyl in soybean sprouts was accelerated at higher temperature and the differences among cultivars became greater at later culture days. The longest of hypocotyl and root lengths of soybean sprouts was obtained from July 5 sowing, followed by May 25 and June 15 sowing. Doremikong and Hannamkong had the thickest and the thinness hypocotyls, respectively. Total length of soybean-sprouts was longer in seeds harvested from later sowing, respectively. Eunhakong produced the longest soybean-sprouts, while Tawonkong produced the shortest. Percentage of rotten seed and imperfectly germinated seed harvested at later sowing was lower. Somyeongkong and Tawonkong showed the highest and the lowest percentages of rotten seeds, respectively, while Pungsannamulkong and Hannamkong showed the lowest and the highest percentages of imperfectly germinated seeds. The soybean-sprouts yields were higher in seeds harvested in 2001 and later sowing. Although Eunhakong and Doremikong showed higher soybean-sprout yield, Pungsannamulkong and Somyeongkong showed stable soybean-sprout yield regardless of the sowing dates.

재배조건이 소형 간식용 고구마 생산에 미치는 영향

김학신,문윤호,정미남,안영섭,이준설,방진기 韓國作物學會 2006 한국작물학회지 Vol.51 No.1S

고구마 소형 간식용 생산을 위한 적정 재배기술 확립을 위하여 고구마 삽식기, 재식거리 및 수확시기를 달리하여 소비자의 선호도에 부응한 간식용으로 적합한 소형 고구마 생산을 향상시키고자 시험을 수행하였던 결과를 요약하면 다음과 같다. 1. 소형간식용 고구마생산을 위한 적정 삽식시기는 4월 중순(피복재배)에 삽식거리는 75cmx15~20cm , 6월 중 순(무피복재배) 삽식시 75cmx15cm 가 적합하였다. 2. 고구마 상저수량은 삽식후 수확일수가 길어질수록 증수되었으나, 삽식후 100일 수확이 80일이나 120일 수확보다 소형 간식용으로 적합한 고구마 괴근 비율이 높았다. 3. 삽식시기 및 삽식거리에 따라 상저수량이 차이가 인정되었으며, 4월 15일 조기 비닐피복재배에서 처리간에 변이폭이 적어 안정적이었다. 4. 보통기(5월) 비닐무피복재배보다 조기(4월) 비닐피복 재배가 농가소득이 32~61% 증가되어 유리하였다. The optimum planting date, plant spacing, and harvest time for production of small-sized sweetpotato was evaluated in 2003 to 2004 at the Mokpo Experiment Station. Small-sized sweetpotato is important as snack food in Korea. Optimum planting date and plant spacing were with plastic mulch, and mid-April and 75~times15~20cm respectively, mid-June and 75~times15cm respectively without plastic mulch. Storage root yield decreased with early harvest, but the ratio of small-sized sweetpotato was higher in plots harvested after 100 days of planting (DAP) than that of 80 or 120 DAP. Considerable differences in storage root yield was noted with planting dates and plant spacings, but the use of plastic mulch resulted to smaller yield variations in plots, harvested in mid-April. Planting in mid-April and harvesting after 100 DAP increased income by about 32~61% compared with plantings mid-May.

Fe-25% Ni 合金과 Fe-25% Ni-0.05% C 合金에 있어서 Marforming 處理 및 Tempering 處理에 依한 機械的 性質에 對하여

金學信,金東健,羅永柱 전북대학교 공업기술연구소 1983 工學硏究 Vol.14 No.-

The mechanical properties of marfomed martensite and martensite tempered for 1hr at 200℃ after marforming treatment with Fe-25% Ni alloy and Fe-25% Ni-0.05% alloy were studied. The former is transformed to martensite at about 93℃ and the latter at about 73℃. The morphologies of two alloys at room temperature were lath martensite, and microstructures of those were examined by optical microscope. Yield strength, ultimate tensile strength and hardness were tested, and X-ray diffractometer(Co-Kα radiation) was used in order to examine retained austenite of two alloys. The results obtained in this study were as follow : 1. The increased strength of Fe-25% Ni alloy subjected to marforming treatment was caused by the work-hardenign induced from the increased dislocation density during deformation, and that of Fe-25% Ni-0.05% C alloy subjected to marforming treatment was caused by the formation of dislocation atmosphere induced from the interaction betwee dislocation cell produced during the deformation and solute carbon, or the stress concentration induced form crossing of twins. 2. The increased strength of two alloys tempered after marforming treatment, compared with two marformed alloys, was caused by the increased elastic modulus due to residual stress-relief. It was examined that the decreased hardness of two alloys tempered after marforming treatment was caused by slight recovery accompanied with the decrease of the stored strain energy, that is, residual stress introduced by transformation and deformation.

공공체육시설 이용자들의 선택과 추구가치가 스포츠복지인식에 미치는 영향

김학신 한국사회체육학회 2020 한국사회체육학회지 Vol.0 No.82

Purpose: The goal of the current study is to survey local residents who use public sports facilities to understand their choices & pursued values and how they impact theipr erception of sports welfare. The ultimate objective is to analyze the results to study the residents’ public sports facility participation & its significance, in order to suggest effective ways to deliver welfare services. Method: Users of three public sports facilities were selected as the population for this study. Excluding forty- five survey responses with suboptimal answers, a total of four hundred six responses were used to conduct empirical analysis. SPSS 24.00 was used to process data by conudcting frequency analysis, reliability analysis , difference test, and multiple regression analysis. Result: First, men who use public sports facilities preferred popula raspects of the facilities, while women preferred public utility. Respondents in their thirties preferred equality, and those in their fifties preferred popular aspects. Those who visit public sports facilities once a week preferred the popular aspects of the faci-li ties, while those visiting more than three times a week preferred public utility. Those who used public sports facilities for five years or longer preferred popular aspects fo the facilities, while those with less than one year of use history preferred public utility. Second, users external choice type for public sports facilities put importance on public utility, while those with internal choice type emphasized equality and public utility. Third, users pursuing objective-driven values prioritized equality and publci utility, while those seeking vitality in life pu t importance on popular aspects. Conculsion: These results indicate that the national welfare policy must emphasize the importance of sports welfare, and to increase the satisfaction of public sports facility users, various specialized measures positioned to enhance the preferred welfare types of various groups should be developed.

가공열처리한 Fe-30%Ni-0.35%C 합금의 역변태거동

김학신,유정희,안행근 한국열처리공학회 1999 熱處理工學會誌 Vol.12 No.4

The reverse transformation behavior was investigated by DSC analysis in thermomechanically processed Fe-30%Ni-0.35%C alloy. Upon increasing the heating rate from 5℃/min to 80℃/min, the As point of the ausformed martensite was not changed and the As point of the marformed martensite decreased at reverse transformation. The Af points showed to be constant with increasing the heating rate both in the ausformed martensite and in the marformed martensite. With increasing the deformation degree, the As points of the ausformed martensite and the marformed martensite increased and the Af points appeared to be constant, structures. The enthalpy changes increased with increasing the heating rate, but decreased with increasing the deformation degree in both structures.

Ausformed Martensite의 擴散型 逆變態處理에 대한 熱力學的 硏究

金學信,金炳日,安幸根,柳正熙 전북대학교 공업기술연구소 1987 工學硏究 Vol.18 No.-

Thermodynamic factors of ausformed martensite and reversed austenite produced from ausformed martensite in Fe-31% Ni-0.2%C alloy have been investigated. The results obtained in this study are as follows : A_b point and A_f point of ausformed martensite increase with the increase of deformation degree when it is deformed below A_d point. The enthalpy change of the reverse martensitic transformation decreases with the increase of deformation degree but the activation energy increases with the increase of deformation degree. The change of chemical free energy of the reverse martensitic transformation is -374.5cal/mole. the calculated and observed enthalph changes of reverse martensitic transformation are 36.5J/g and 24.5J/g respectively. The strain energy produced by the reverse martensitic transformation is considered to be about 300~500cal/mole.