Prediction of Retained Austenite Fraction in Quenching-and-Partitioning (Q&P) Steels Using the Gibbs Energy Balance Approach

Seong Hoon Kim,Ji Hoon Kim,Jae Hoon Lee,Dong‑Woo Suh,Jae Sang Lee 대한금속·재료학회 2022 METALS AND MATERIALS International Vol.28 No.9

Prediction of retained austenite fraction is quite important in designing advanced high strength steels since retained austeniteis the source of transformation-induced plasticity. The present study investigates the phase constitution of a medium-carbonQ&P steel by comparing various approaches to the transformation stasis of bainitic ferrite and applying them to the partitioningprocess. Among them, the modified GEB approach gave the best agreement with the experimental observation, includingthe effects of heat-treatment condition and chemical composition on phase constitution. This indicates phase transformationduring partitioning can be effectively described by the physics of Gibbs energy balance approach.

상악 제2유구치와 상악 제1대구치의 치관 형태: 치아계측학적 연구

김지인,현홍근,김영재,김정욱,장기택,이상훈,한세현,김종철 大韓小兒齒科學會 2011 大韓小兒齒科學會誌 Vol.38 No.4

The basic structure of the primary crowns usually resemble their succeeding permanent teeth. However, maxillary second primary molars resemble ipsilateral first permanent molars. Accordingly in this study, odontometric data of the two teeth was obtained, then analyzed to verify the morphological relationship and sex difference between the two teeth. Dental study casts were examined for their mesiodistal and buccolingual width of the crowns, diameter of each cusps, and intercuspal distances. Photographs of the crowns were taken to measure the angles between each cusp tip. The results are as follows : 1. In boys, PrI, PaI, DBC angle, and MBC angle did not show any statistically significant difference between the two teeth(p>0.05), and moderate level of correlations were observed. 2. In girls, crown index, DBC angle, and MBC angle of the two teeth did not show any statistically significant difference(p>0.05), and moderate level of correlations were recognized. 3. Measurements that did not show statistically significant difference between the two teeth in both boys and girls were DBC angle and MBC angle(p>0.05). In DLC angle, however, statistically significant difference was observed(p<0.01). 4. Most of the measurements showed sex differences, except DBC angle, which did not show any sex difference in both teeth(p>0.05). 유치 치관의 기본적인 구조는 대개 계승 영구치를 닮는다. 그러나 제2유구치는 계승 영구치인 제2소구치보다 오히려 제1대 구치와 더 유사한 경향이 있다. 이에 본 연구는 한국인에서 상악 제2유구치와 제1대구치의 치아계측학적 자료(odontometric data)를 얻어 두 치아의 형태와 크기 사이의 연관성을 살펴보고, 나아가 남녀간의 차이점 유무를 고찰해 보고자 하였다. 남아 150명, 여아 150명 총 300명의 모형을 이용하여 상악 제2유구치와 상악 제1대구치의 근원심 치관 폭경, 협설측 치관 폭경, 각 교두의 직경, 교두정간 거리를 계측하였고, 치관의 교합면 사진을 촬영하여 각 교두정 사이의 각도를 측정하여 다음과 같은 결과를 얻었다. 1. 남아에서 Protocone index, Paraconeindex, Distobuccal cusp(DBC)각, Mesiobuccal cusp(MBC)각은 상악 제1대 구치와 제2유구치 사이에 통계적 유의차가 관찰되지 않았고(p>0.05), 중등도의 상관관계가 확인되었다. 2. 여아에서 crown index, Distobuccal cusp(DBC)각, Mesiobuccal cusp(MBC)각은 상악 제1대구치와 제2유구치 사 이에 통계적 유의차가 관찰되지 않았고(p>0.05), 중등도의 상관관계가 확인되었다. 3. 남, 여 모두에서 Distobuccal cusp(DBC)각, Mesiobuccal cusp(MBC)각은 두 치아 사이에 유의할만한 차이를 보이 지 않았고(p>0.05), Distolingual cusp(DLC)각에서는 통계적 유의차가 관찰되었다(p<0.01). 4. 대부분의 계측치에서 남녀 차이를 나타냈지만, Distobuccal cusp (DBC)각은 상악 제1대구치와 제2유구치 모두에서 남녀 차이를 보이지 않았다(p>0.05).

Tuning the Microstructure and Mechanical Properties of Cold Sprayed Equiatomic CoCrFeMnNi High-Entropy Alloy Coating Layer

Ji‑Eun Ahn,Young‑Kyun Kim,Sang‑Hoon Yoon,Kee‑Ahn Lee 대한금속·재료학회 2021 METALS AND MATERIALS International Vol.27 No.7

An equiatomic CoCrFeMnNi high entropy alloy (HEA) coating layer was prepared via a cold spray (CS) process. In orderto control the microstructure and nano-indentation properties of the CS HEA, heat treatments were employed. CS HEAcoating layer showed a heterogeneous microstructure where ultra-fine grains were formed at the particle interfaces, whilecoarse grains were formed inside the particles. Furthermore, deformation twins (DTs) were also formed inside the particlesdue to severe plastic deformation (SPD) in each particle generated during the CS deposition. For the 550 °C heat treatment(HT), fine Cr-rich precipitates were additionally formed at the grain boundary and particle boundary. By contrast, recrystallizationoccurred during 850 °C HT, while the size of the Cr-rich precipitate increased. The nano-indentation hardness ofthe CS HEA coating layer was 10.9 GPa, which was ~ 3 times higher than that of the conventional cast HEA. The superiorhardness of the CS HEA might has been enabled due to the combination of the high dislocation density, DTs, and ultra-finegrains. Based on the results above, the strategy to control the microstructure and mechanical properties through HT of theequiatomic CoCrFeMnNi HEA coating layer prepared via the CS process has been discussed.

색상 측정 기기를 이용한 복합레진 적층 수복과 단일 수복의 색상 비교 분석

송영상,김자현,이빈나,장지현,장훈상,황윤찬,오원만,황인남 大韓齒科保存學會 2012 Restorative Dentistry & Endodontics Vol.37 No.2

Objectives: This study analyzed the difference in color caused by different thickness in enamel layer of composite resins when applied with single and layering placement technique, and evaluated if the results agreed with the shade guide from the manufacturers to verify reliability of the color matching process of the manufacturers. Materials and Methods: For single composite resin samples, 6 mm diameter and 4 mm thickness cylindrical samples were fabricated using Ceram-X mono (DENTSPLY DeTrey) and CIE L*a*b* values were measured with spectrophotometer. Same process was done for layering compositie resin samples, making 3 dentinal shade samples, 4 mm thickness, for each shade using Ceram-X duo (DENTSPLY DeTrey) and enamel shade resins were layered in 2 mm thickness and CIE L*a*b* values were measured. These samples were ground to 0.2 mm thickness each time, and CIE L*a*b* values were measured to 1 mm thickness of enamel shade resin. Results: Color difference (△E*) between single and layering composite resin was 1.37 minimum and 10.53 maximum when layering thicknesses were between 1 mm and 2 mm and 6 out of 10 same shade groups suggested by manufacturer showed remarkable color difference at anythickness (△E* > 3.3). Conclusion: When using Ceram-X mono and duo for composite resin restoration, following the manufacturer's instructions for chossing the shade is not appropriate, and more accurate information for Ceram-X duo is needed on the variation and expression of the shades depending on the thickness of the enamel. (Restor Dent Endod 2012;37(2):84-89)

허혈성 심질환에서 나타나는 황상화지수, 사이토카인 및 염증지표의 변화

전상훈,안지훈,방덕원,온영근,현민수,김성구,권영주 순천향대학교 의학연구소 2004 Journal of Soonchunhyang Medical Science Vol.10 No.3

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다발성 근염 환자에서 발생한 스테로이드 근병증 1예

이지훈,현신영,김충기,이수환,최아라,김성우,박성혜,이찬희 영남대학교 의과대학 2011 Yeungnam University Journal of Medicine Vol.28 No.2

Polymyositis is diffuse, inflammatory myopathy with proximal-muscle weakness due to lymphocyte infiltration to the muscle layer. The exact cause of the muscle weakness is unclear but may be related with an immunologic mechanism. Using high-dose steroid is the treatment of choice for polymyositis. It is difficult to distinguish steroid-resistant polymyositis from steroid myopathy, however, in the course of high-dose steroid therapy. These authors encountered a steroid myopathy patient during polymyositis treatment with high-dose steroid. A 57-year-old woman was diagnosed with polymyositis and was treated with high-dose steroid. Her condition was initially improved, but in the course of the treatment, her symptom was aggravated without increasing the muscle enzymes. Her muscle weakness was improved by reducing the steroid dosage.

성장기 아동의 single tooth scissors bite의 교정 치료: 증례 보고

김지인,현홍근,김영재,김정욱,장기택,이상훈,한세현,김종철 大韓小兒齒科學會 2011 大韓小兒齒科學會誌 Vol.38 No.4

A scissors bite in the posterior teeth occurs when the upper teeth are positioned totally buccal to the lower teeth in centric occlusion, either unilaterally or bilaterally. This malocclusion can result from either excessive width of the maxilla or deficient width of the mandible, or sometimes combination of the both. Scissors bite, when left untreated without a proper dental intervention, interferes with the normal mandibular growth leading to a state where consequent disharmony in dental arch width evokes occlusal disturbances. Therefore, early preventive orthodontic treatment is necessary in patients with scissors bite. Scissors bite rarely involves anterior and posterior sites concuttently across the dental arch but usually affect single tooth. Even in the single tooth scissors bite cases, more likely to be met in the clinical fields, immediate dental intervention is indicated because continuous occlusal forces that exacerbate the already adverse axis of the posterior teeth. In this case study, patients with single tooth scissors bite, each 7, 14, 12, and 16 years old, were each treated with criss-cross elastic, fixed appliance, removable appliance, and miniscrews. With the proper selection of appliances appropriate to each specific cases, good treatment outcome can be achieved without resulting any side effects. 중심교합위의 상태에서 편측 혹은 양측으로 상악 구치부의 치아가 하악 구치부의 협측으로 위치한 경우를 scissors bite라 고 한다. 이는 상악의 폭경이 크거나 하악의 폭경이 좁은 경우 발생한다. Scissors bite의 경우 방치하게 되면 하악의 성장이 방해받게 되고 그 결과, 악궁 폭경의 부조화가 심해져 저작 장애를 일으킬 수 있으므로 조기 차단 교정이 반드시 필요하다. 실제 임상에서는 여러 치아의 scissors bite보다 최후방 구치 혹은 그 외 하나의 구치만의 single tooth scissors bite(STSB)을 보이는 경우가 많다. 이러한 STSB의 경우도 방치하게 되면 저작력으로 인하여 구치의 각도가 더욱 악화되므로 즉각적인 치료가 필요하다. 본 증례에서는 STSB를 보이는 7세, 14세, 12세, 16세의 환자에게 각각 criss-cross elastic, 고정성 장치, 가철성 장치, miniscrew를 사용하여 치료한 증례를 보고하였다. 각 환자의 증례에 적합한 장치를 잘 선택하여 사용한다면 치아를 정출시키는 등의 부작용을 야기하지 않고 양호한 결과를 얻을 수 있을 것이다

TSC 합성보의 제작방법에 따른 구조적 거동에 관한 실험적 연구

이지운,김도훈,김성배,이창남,김상섭,김규석 대한건축학회 2004 대한건축학회 학술발표대회 논문집 - 계획계/구조계 Vol.24 No.1(구조계)

Composite action can be achieved by providing shear connectors between steel top flange and concrete topping. Composite sections have larger stiffness than the summation of the individual stiffness of slab and beam, therefore, can carry larger load or similar loads with appreciably smaller deflection and are less prone to transient vibration. T-type Steel Composite beam(TSC-beam) is developed and tested. To make the part of steel beam, we used the way of welding two steel plates as well as the way of folding one steel plate.

점적상에서의 수력학 특성

조지훈,성기천,함병호,김태옥 明知大學校 産業技術硏究所 1991 産業技術硏究所論文集 Vol.10 No.-

Hydrodynamics was investigated in a trickle bed with spherical particles. Flow transition boundary, pressure drop, and liquid holdup were measured and analyzed in an air-water system. The results showed that liquid velocity at trickle-pulse transition boundary increased with increasing packing size and it decreased with increasing gas velocity, and that the theoretical model proposed was well applicable to predicted flow transition boundary. In the same operation conditions, flow characteristics was changed with operation mode because of liquid closslinking. Therefore, as the maximum gas velocity increased, pressure drop increased. Also, pressure drop increased with increasing fluid velocity and it increased with decreasing packing size, and the effect of gas velocity on pressure drop for higher liquid velocity was less than that for lower liquid velocity. Liquid holdup increased with increasing liquid velocity and it decreased with increasing packing size, and the influence of gas velocity on liquid holdup for pulse flow regime had larger than that for trickie flow regime. By contrast, the influence of packing size on liquid holdup for pulse flow regime had less that for trickle flow regime. In this conditions, correlations of pressure drop and liquid holdup were proposed in terms of Reynolds numbers of total fluids and liquid phase.

HL-60 세포의 성장에 대한 제주자생 해조류의 효과

김상철,박수영,김병석,강지훈,김세재 제주대학교 생명과학기술혁신센터 2002 제주생명과학연구 Vol.5 No.-

The purpose of the present study is to examine the inhibitory effect of extracts of marine algae growing in Jeju on the growth of HL-60 leukemia cells. The effect was observed by measurement of metabolic activity and counting of viable cells. The methanol extracts on 36 species of marine algae growing in Jeju were screened for cytotoxic effect at the concentration of 100㎍/㎖. In results, the inhibitory effect on the growth was observed in the treatment of crude extracts on 7 species of marine algae. In particular, Dictyota dichotoma, Myelophycus simplex, Laurencia okamurae, Plocamium telfairiae, Petalonia binghamiae, Codium minus marketdly inhibited the growth of HL-60 cells.