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.

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.

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)

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

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.

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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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).

허혈성 심질환에서 나타나는 항산화지수, 사이토카인 및 염증지표의 변화

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

Purpose : As diet habits change and the elderly popuation increases conronary artery disease(CAD) has also increased. Recent ongoing studies on varous inflammatory indexes in acute coronary syndrome(ACS) are underway. Several study results have shown that total antioxidant status(TAS) was remarkably lower in unstable angina than in chronic stable angina and levels of interleukin-(IL-6), C-reactive protein(CRP), monocyte chemoattractant protein-1(MCP-1), P-selectin were reported to be elevated in unstable angina and acute myocardial infarction(AMI). In our study, we studied and compared the level changes of cytokines and inflammatory indexes that play important roles inside the blood vessel. Methods : Study subjects were patients who were admitted and underwent coronary angiography at the cardiology department in Soonchunhyang university hospital. Subjects were divided into 4 groups, a control group, a stable angina and unstable angina group and an acute myocardial infarction group. The clinical findings, TAS, inflammatory cytokines(P-selectin, MCP-1, IL-6), anti-inflammatory cytokines(IL-10), Homocysteine and CRP levels in each group were measured and compared. Results : The total number of study participants was 86 patients, with 26 patients in the control group, 21 patients with stable angina, 15 patients with unstable angina, and 24 patients with AMI. There were significant differences in the TAS among the 4 grouops. 1.7±0.51 mmol/L, 1.6±0.60 mmol/L, 1.4±0.20 mmol/L, 1.4±0.29 mmol/L respectively. IL-6 levels also showed a significant difference between groups, averaging 0.8±2.47 pg/ml, 2.7±3.77 pg/ml, 6.8±10.63 pg/ml, 10.9±17.43 pg/ml respectively. Homocysteine levels averaged 8.0±2.47 pg/ml, 6.8±10.63 pg/ml, 10.9±17.43 pg/ml restectively. Homocysteine levels averaged 8.0±1.0 μmol/L in the control group, 14.3±5.14 μmol/L in patients with stable angina, 16.0±4.66 μmol/L in patients with unstable angina, and 17.3±10.08 μmol/L in AMI patients. Conclusion : Compared to the control group, the TAS levels were significantly lower in patients with unstable angina and AMI. there was no difference between the control group and those with stable angina. IL-6 and homocysteine levels were also higher in patients with unstable angina and AMI. Therefore we concluded that measurements of TAS, IL-6 and homocysteine are useful in measuring the inflammatory index of coronary artery diseases and may be important factors in predicting the states and prognosis of cardiovascular disorders.

포퓰리즘, 데모스, 급진민주주의 - 라클라우와 무페에게서 ‘인민’의 담론적 구성에 관하여 -

한상원 한국철학사상연구회 2020 시대와 철학 Vol.31 No.2

오늘날 정치에 관한 사유들은 포퓰리즘이라는 현상을 비껴갈 수 없을것이다. 그런데 포퓰리즘을 둘러싼 관점들은 종종 양극단의 대립을 드러낸다. 포퓰리즘은 일종의 우려할만한 사건인가, 아니면 그 자체로 필수불가결한 민주주의 사회의 근본 전제인 것일까? 다시 말해, 포퓰리즘의 세계적확산은 오늘날 현대 사회를 파국으로 밀어넣을 것인가, 아니면 그 안에서 새로운 희망을 발견할 수 있을 것인가? 2018년 프랑스 파리에서 일어난 노란조끼 운동은 무엇을 반복하고 있는가? 1789년 7월 14일의 성난 군중인가, 아니면 1923년 11월 9일의 뮌헨 맥주집 폭동일까? 그들은 혁명의주체 프롤레타리아인가, 아니면 폭민인가. 혹은 둘 다일까? 이와 같은 논의는 근본적으로 민주주의의 주체로 상정되는 인민 혹은 데모스의 범주를 어떻게 이해할 것인가와 직접 관련되어 있다. 본 논의는 ‘포스트 맑스주의’를선언하며 급진민주주의 전략을 제시한 라클라우와 무페가 포퓰리즘에 관해도발적으로 제기하고 있는 정치철학적 사유를 소개하면서, 그 의미와 성과, 그리고 한계를 지적하고자 한다. Thoughts on politics today are not able to avoid the phenomena of populism. The perspectives on the populism often reveal the opposition between two extremes. Is populism a sort of worrisome event, or is it an inevitable fundamental precondition of democratic society? Is the global spread of populism going to drive modern society into catastrophe, or can we find new hope in it? What did the yellow vest movement repeat in Paris in 2018? Was it the raging crowd on July 14, 1789, or the Munich brewery riot on November 9, 1923? Are they the proletarians of the revolution or the mobs? Or is it both? This discussions are directly engaged to how to understand the categories of People or Demos, which is regarded as the subject of democracy. In this article, I will try to show the meaning, achievements, and limitations of Laclau and Mouffe, who proclaimed ‘Post Marxism’ and suggested the strategy of radical democracy, proposing the political philosophy of populism.

기-액병류상향 충전탑에서 액체체류량과 축방향혼합특성

조지훈,손민일,박용성,함병호,김태옥 明知大學校 産業技術硏究所 1993 産業技術硏究所論文集 Vol.12 No.-

For upward cocurrent gas-liquid flow in a packed column, holdup and axial mixing characteristics of liquid were investigated. In an air-water-glass bead system. liquid holdup and residence time distribution(RTD) were measured and Peclet number based on axial dispersion model was evaluated from experimental RTD. We found that liquid holdup was increased with increasing liquid velocity and size of packing material, and it was decreased with increasing gas velocity. Also, liquid holdup for the cocurrent up flow system was larger than that for the downflow system at the same experimental conditions. As increasing gas velocity, the in fluence of packing size and operation method on liquid holdup was reduced. The calculated Peclet number was not affected by gas velocity, and it was increased with increasing liquid velocity and with decreasing packing size. Furthermore, the effect of liquid velocity on Petlet number for higher liquid Reynolds number(Re1>70) was larger than that for lower Re1. In these conditions, correlations of the dynamic liquid holdup and the Bodenstein number were obtained.