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.

레저스포츠 제품에 대한 가치지각이 재구매의도와 충성도에 미치는 영향

김학신,박용범 한국사회체육학회 2003 한국사회체육학회지 Vol.20 No.2

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.

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.

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.

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.

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.

나물용 콩 풍종의 파종기에 따른 수량구성요소 및 수량 변이

김학신,김홍식,김경호,오영진 韓國作物學會 2006 Korean journal of crop science Vol.51 No.7

본 연구는 나물용 콩의 파종기가 콩나물 원료콩의 수량구성요소 및 수량에 미치는 영향을 구명함으로써 양질 콩나물 품종육성과 콩나물 원료콩의 안정적 생산 공급을 위한 기초 자료를 얻고자 2000~2001 년에 호남농업연구소 전작시험 포장에서 파종시기 시험을 수행하였던 결과를 요약하면 다음과 같다. 1. 개체당 협수, 공협수, 입수 및 100립중은 파종기 및 품종간에 차이가 있었으며, 파종기가 늦어짐에 따라 감소하였다. 협당 입수별 협수의 분포비율은 2~3 립 협이 80.9~77.5% 이었으며 파종기에 따라 2립 협의 변이가 컸다. 2. 수량은 2년간 시험품종 평균 5월 25일 파종은 290 kg/10a, 6월 15일 파종은 269 kg/10a 및 7월 5일 파종은 221 kg/10a으로 파종기가 늦어질수록 감소하였고, 풍산나물콩이 수량이 가장 높았으며 파종기에 따른 수량 감소 정도가 적었고 그 외 품종들은 파종기에 따른 수량의 감소 정도가 컸다. 3. 수량은 개화일수, 성숙일수, 생육일수, 분지수, 줄기굵기, 개체당 협수, 개체당 입수 및 개체당 엽면적과 정의 상관이었으며 개체당 협수는 개체당 입수, 개체당 엽면적 및 건물중과, 개체당 입수는 개체당 엽면적 및 건물중과 정의 상관이었다. This study was conducted to investigate the effects of sowing date on yield component and yield in sprout-soybean. Six sprout-soybean cultivars were planted on three sowing dates in 2000 and 2001. 100-seed weight, number of seeds per pod, number of seeds, number of pods per plant, and ratio of empty pods distinct differences between sowing dates and cultivars. All yield components except the 100-seed weight and number of seeds per pod diminished recording where the sowing day will be late. The ratio of pods with two or three seeds was 77.5 from 80.9 percents. The ratio of two-seed pods were affected by sowing date. The yield of soybean of May 25 sowing was 290 kg/10a followed by June 15 and July 5 sowing with 269 kg/10a and 221 kg/10a, respectively Late sowing greatly decreased the yield of Doremikong, while yields of Tawonkong were more a less stable. In 2000, yield showed positive correlation with number of branches, number of pods per plant, number of seeds per plant, dry weight, leaf area, and oil content. While yield of 2001 showed positive correlation with number of nodes on main stem, stem thickness, number of pods per plant, dry weight, and leaf area

Pb-Sb 合金의 時效析出에 對하여(1)

金學信 전북대학교 공업기술연구소 1979 工學硏究 Vol.9 No.-

In this paper, Electrical resistance and micro-hardness measurements versus ageing time were performed for studying the influences of the antimony content and of a plastic deformation imm-ediately after quenching on ageing precipitation of Pb-Sb alloys. The results obtained in this study are as follows : 1. the hardness increase in the first stage of ageing process can be explained by cluste-ring of quenched-in excess vacancies. 2. Ageing precipitaion takes place faster when antimony content is higher. 3. The influences of a plastic deformation just after quenching lead to a greater ageing kinetics and accelerate ageing precipitation.