Phase Transformation Modeling for Hypo Peritectic Steel in Continuous Cooling

Jun‑hyun Jo,Kyung‑woo Yi 대한금속·재료학회 2021 METALS AND MATERIALS International Vol.27 No.7

Phase change of steel during cooling affects the slab qualities in continuous casting. Especially, crack susceptibility of hypoperitectic steel is high because large volume shrinkage occurs by peritectic phase transformation during solidification andcooling. In continuous cooling, phase change is different from the behaviors under the equilibrium condition, such as undercoolingand extend of peritectic reaction, etc. Therefore, we develop a new phase change model considering thermodynamics,empirical equations, and carbon diffusion in each phase to predict phase change behavior during continuous cooling. Inthis model, phase change of hypo peritectic steel comprises 5 stages until all phases become the γ phase. The velocities ofthe δ/γ interface and phase fractions during cooling are calculated according to cooling rate, undercooling of the γ phase,and carbon contents. The results show that if solidification ends by the δ phase during dTp,the γ phase is formed by massivetransformation. On the contrary, if peritectic reaction starts with liquid, the γ phase is formed and grows by diffusionaltransformation. In latter case, massive transformation of remaining δ phase can occur with high undercooling or very fastcooling rates. This analysis shows that there are several different paths depending on carbon contents of hypo peritectic steels.

김치에서 분리한 Lactobacillus sp. JC-7과 Lactobacillus acidophilus 88간의 Electrofusion 최적조건 설정

조영배,최현정,백형석,전홍기 부산대학교 유전공학연구소 1997 분자생물학 연구보 Vol.13 No.-

김치 발효 숙성기간을 연장하고 신선도를 오랫동안 유지 할 수 있는 김치발효 starter의 개발을 목적으로 최적숙성기에 있는 김치로부터 bacteriocin생성능이 없는 유산균을 분리하여 동정하였으며, bacteriocin생성능이 우수한 L.acidophilus 88을 융합시키기 위해 electrofusion에 대한 최적 조건을 검토하였다. 분리균주는 Lactobacillus속으로 동정되어 Lactobacillus sp. JC-7이라 명명하였다. Electrofusion에 의해 생성된 융합주를 식별하기 위해 streptomycin(2.5㎎/ml)에 내성을 나타내는 Lactobacillus sp. JC-7변이주와 kanamycin(600㎍/ml)에 내성을 나타내는 L.acidophilus 88변이주를 분리하였다. Electrofusion을 100V/㎝, 120msec(72ohms,1670 capacitance) 에서 수행했을 때 융합효율이 가장 양호하였으며 전기장의 세기와 시간이 중가할수록 융합 효율이 현저히 감소하였다. 2가 양이온은 농도가 중가할수록 대체적으로 융합효율을 감소시키는 경향을 나타내었으나 1mM MGCl_2에서는 대조군에 비해 융합효율이 약간 증가하였다. PEG매개에 의한 융합법의 융합효율을 비교한 결과, 융합효율은 chemical fusion<electrofusion<electrofusion+20% PEG순을 나타내었다. Evaluation of Optimum Conditions for the Electrofusion between Lactobacillus sp. JC-7 Isolated from Kimchi and Lactobacillus acidophilus 88. Young-Bae Jo, Hyun-Jung Choi, Hyung-Suk Baik and Hong-Ki Jun*. Department of Microbiology, Pusan National University, Pusan 609-735,Korea-A lactic acid bacterium was isolated from kimchi. The isolated strain was identified as the genus Lactobacillus thrugh its morphological characteristics and named as Lactobacillus sp. JC-7. The optimum conditions for the electrofusion between streptomycin(2.5㎎/ml)resistant mutant of Lactobacillus acidophilus 88 and kanamycin(600㎍/ml) resistant mutant Lactobacillus sp. JC-7 were evaluated. The highest number of fusants were obtained at a capacitance value of 120msec(1670㎌), a field strength of 100V/㎝,and a pulse controller setting of 72Ω. The potimum pH of elecroporation buffer was 7.5 and the concentration of divalent cation was 1mM MG^2+. Electrofusants were efficiently obtained by addition 20% polyethylene glycol to electroporation buffer. The yield of fusion was better than that of using polyethylene glycol mediated chemical induction.

Numerical Analysis on Crack Generation Behavior of Hypo Peritectic Steel in Continuous Casting Process

Jun‑hyun Jo,Min‑seok Park,Kyung‑woo Yi 대한금속·재료학회 2021 METALS AND MATERIALS International Vol.27 No.11

Hypo peritectic steels exhibit a high possibility of longitudinal crack during continuous casting. Therefore, many researchershave studied the mechanisms of crack generation in hypo peritectic steel. Stress in solidified shell, or volume contractionwith small liquid fractions were suggested as the mechanisms of crack generation. A new model was developed for predictingpossibility of crack generation by calculating strain rates in solid, volume contraction rate during solidification, and theprobability of liquid unfilling in continuous cooling processes. The results show that massive transformation from the δphase to the γ phase, and peritectic transformation during solidification can be the main crack generation mechanisms. Furthermore,a linear relationship exists between the amount of undercooling for peritectic transformation (dTp) and the carboncontent of the boundary for dividing the two crack generation mechanisms. Additionally, the longitudinal crack ratios ofthe field results are analyzed through strain rates in solid and liquid unfilling possibilities. Relative positions in the range ofhypo peritectic steel and effective carbon contents are suggested to analyze the crack ratio of steels with alloying elements. This analysis shows that the results obtained from the new models for crack generation possibility are usable, and dTpcangenerate the behavioral differences in crack generation according to the conditions.

관동맥질환에서 저밀도 지단백 입자 크기의 분포

임효영,김인숙,승기배,강동헌,전두수,장기육,박준철,이수영,홍순조,최규보 대한순환기학회 1998 Korean Circulation Journal Vol.28 No.8

벼농사용 주요 농기계의 적정 교채시기 분석

조성주,이준배,박평식 충북대학교 농업과학기술연구소 2000 農業科學硏究 Vol.17 No.-

Farm machineries are subjected to deterioration with usage and age. System deterioration is often reflected in high production costs and lower product quality. To keep production costs down while maintaining good quality, preventive maintenance is often performed on systems subject to deterioration, The growing importance of maintenance has generated an increasing interest in the development and implementation of preventive maintenance models for deteriorating systems. The deterioration law of farm machineries, old-fashioned, inadequateness, i.e., the change of state, is assumed to follow a semi-Markov process made in accordance with a discrete Markov chain and time spent in each state before a transition occurs is random variable depending on the transition. These rates depend upon the holding time in the states and the actions can be changed at any point in time, not just at transsition time. Since all states ordered, it is presumably more cost to operate the machine in a less desirable state. The system is observed periodically and classified into one of a finite number of states. On the basis of the observations certain maintenance or replacement decisions are made. Transitions probabilities from state to state are determined by the decisions. These actions will bring the system back to the better states with probability. Using a simplex algorithm drawn from the area of Linear Programming, this study demonstrates how a typical sequential probabilistic model may be formulated in terms of a decision rule, specifying order quantities as a function of initial state conditions, and a semi-Markov process in which the transition probabilities depend both upon the decision rule and also upon the probabilities distribution of states. The results of this study were as follows; The average span of major items of farm machineries are 131.9 ha in tractor, 102.4 ha in rice transplanter 6-rows, and 145.5 ha in 4-rows combine. The optimal policy calls for self preventive maintenance and repairing cost is 800,000won the tractor when it is in state 0 and state 1, consignment preventive maintenance and repairing cost is 2000,000 - 2140,000 won when in state 2 and 3. The optimal policy calls for self preventive maintenance and repairing cost is 800,000 won the 4-rows combine when it is in state 0 and 1, consignment preventive maintenance and repairing cost is 2,920,000 won when it is in state 2, overhaul cost is 3,980,000 won when it is in state 3. The optimal policy call for self proventive maintenance and repairing cost is 290,000 won the 6-rows transplanter when it is in state 0 and 1, consignment preventive maintenance and repairing cost is 970,000 - 1,070,000 won when it is in state 2 and 3.

그레이브스병에서 방사성 요오드 치료에 따른 갑상선 자극 호르몬 수용체 결합억제 면역글로불린(Thyrotropin Binding Inhibitory Immunoglobulin, TBII)의 변화

조영석,권기현,이준철,나소영,이효진,홍우정,이유선,김군순,송민호,김영건,노흥규 충남대학교 의학연구소 2003 충남의대잡지 Vol.30 No.2

Prediction of thrapeutic response to radioiodine in Graves' disease is poorly understood. Although thyrotropin binding inhibitor immunoglobulin(TBII) level is a strong index for relapse after antithyroid drug medication, conflicting results are reported regarding its prognostic significance in Graves' disease treated with RAI. This study is dengned to evaluate possible relationship between post-treatment hypothyroidism and TBII in Graves' disease treated with RAI. Fourty two patient with Graves' disease after radioiodine treatment were studied retrospectively. The subject were divided into hypothyroid group and euthyroid or hyperthyroid group. We evaluated the association of hypothyroidism and TBII with radioiodine treatment dose. The mean age of hypothyroid group was 48±11 years and euthyroid or hyperthyroid group was 47±12 years. There was no difference in two groups. And there was no significant difference in post- treatment TBII between two groups(49.9±28.5%, 29.9±14.3%, p-value >0.05). The treatment-dose had no influence on post-treatment thyroid state. Euthyroid or hyperthyroid group was done with 13.6±6.9mCi and hypothyroid group was 17.0±10.4mCi(p-value > 0.05). TBII had no prognostic significance on long-term hypothyrodism in Graves' disease treated with radioiodine. And, treatment-dose had no influence on post-treatment thyroid state.

음운감수성 훈련이 5세 유아의 읽기 능력 발달에 미치는 영향

조준수 한국영유아보육학회 2004 한국영유아보육학 Vol.0 No.39

본 연구는 음운 감수성 훈련을 통해 유아의 읽기 능력 향상이 가능한지를 살펴보았다. 연구 대상자는 실험집단 25명, 통제집단 25명으로 유치원에 다니는 만 5세 아동이었다. 실험집단의 유아를 대상으로 음소지각, 음절탈락, 음소탈락, 음소변별, 읽기와 철자법의 지도를 8주 동안 실시한 후, 의미 단어와 무의미 단어 읽기 능력을 측정하였다. 연구결과 음운 감수성과 읽기 능력간에는 유의한 상관이 있는 것으로 나타났다. 음운 감수성 훈련을 받은 유아들은 음소지각이 낮은 유아를 제외하고, 각 요인별 음운 감수성 정도에 관계없이 무의미 단어 읽기 능력이 향상된 것으로 나타났다. 또한 의미단어 읽기 능력은 각 요인별 음운 감수성이 높은 유아에게만 훈련의 효과가 있는 것으로 나타났다. 연구결과는 음운 감수성이 유아의 읽기 능력을 발달시킬 수 있는 기술의 하나로 고려될 필요성이 있음을 시사한다. The effects of phonological sensitivity training on development of reading ability were examined with forty-nine kindergarten children. Subjects were divided into an experimental and a control group. The phonological sensitivity training(syllable deletion, phoneme deletion, sound categorization, phonetic recoding) were applied in the experimental group for 8 weeks. Children who received phonological sensitivity training were significantly higher on the scores of meaningful and nonsense words reading test in the post-test than the control group children. Findings suggest that reading was ability somewhat influenced by phonological sensitivity.

웹 질의 기반의 동적 웹 에디터 시스템의 설계 및 구현

조준호,임종수,김응모 成均館大學校 科學技術硏究所 2000 論文集 Vol.51 No.1

As web environment and technology improve rapidly these days, many users get desirable information by means of web, and represent the information that they have through web pages construction. Therefore, importance and application of web editor for easy and convenient homepage making have increased. In this paper, we propose a web query system based on dynamic web editor. The editor makes it possible for users to conveniently make homepages by improving limit of client based web editor or template web page service supplied by hosting site. And users search for desirable information through web pages on the huge web, so they can add this information for users web page or create new web page. Through this web editor which implements server based on the web, users can make web page flexiblely and can make polished web page which increases reading and comprehensiveness to access information easily.

침엽수로부터 발생되는 방향성 테르펜의 배출속도 비교 연구

김조천,홍지형,강창희,선우영,김기준,임준호 한국대기환경학회 2004 한국대기환경학회지 Vol.20 No.2

In order to investigate the composition ratio and the emission rate of monoterpenes emitted from coniferous trees during summer, the enclosure chamber experiments were carried out for two tree species (Pinus densiflora and Pinus rigida). The major monoterpenes from the pine trees were α-pinene, β-pinene, myrcene and β-phellan-drene. There was no difference of the composition ratio between two sites for P. densiflora, but the difference was observed for P.rigida, Clearly, the ratio of β-pinene (26.1%) for P.rigida was higher than that of β-phellandrene (12%) at the Gumsung mountain site, but the ratio of β-phellandrene (22.2%) was higher than that of β-pinene (9.9%) at the Chiri mountain site. Particularly, the composition ratio of β-phellandrene was higher than that of β-pinene for P.densiflora, and the opposite trend was found for P.rigida at the Gumsung mountain site. The characteristics of the composition ratio between two species were similar at the Chiri mountain site. As a result of the emission rate measurements, it was observed that both sites did not show any significant β value (slope between emission rate and temperature) and ERs (Standard Emission rate at 30℃) difference. However, the β value and ERs at the Chiri mountain site were slightly greater than those of Gumsung mountain site for both pine species. P.densiflora(1.703 and 1.971㎍C/gdw/hr) showed the higher monoterpene ERs than those of P.rigida (0.572 and 0.698 ㎍C/gdw/hr) at both sites.

원발성 후복막 점액낭샘암종 1예

지준호,이화정,박승찬,박정철,최은정,서혜진,이원식,이정림,배병조,손경락,이경희 영남대학교 의과대학 2008 Yeungnam University Journal of Medicine Vol.25 No.2

Primary retroperitoneal mucinous cystadenocarcinoma is a very rare malignancy, and little is known concerning its Pathogenesis, optimal treatment, and prognosis. A 29-year-o1d pregnant woman (21 weeks) Presented with abdominal discomfort CA 19-9, CA 125, and CEA were normal Abdominal CT scanning revealed a 19x15x13 cm retropentoneal tumor Exploratory laparotomy and tumor excision were performed. Mucinous retropentoneal implants were removed as completely as possible Histologically, the tumor showed focal areas of capsular invasion, but free resection margins The uterus and both ovaries were normal in appearance No adjuvant therapy was pursued. Six months later, Peritoneal and bilateral ovarian metastases were discovered. Hence, we report the details of this case of primary retroperitoneal mucinous Cystadeno-carcinoma and present a review of the literature.