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.

한국인에서의 CYP2C19 돌연변이 유전자형의 다형성에 관한 연구

채석,채상우,양동규,김형기,권준택,염윤기 순천향의학연구소 2000 Journal of Soonchunhyang Medical Science Vol.6 No.2

The S-mephenytoin 4'-hydroxylase (CYP2C19) metabolizes a number of clinically used drugs and shows a marked interethnic difference in the incidence of the poor metabolizer (PM). Recent studies have found a third (CYP2C19*4) and forth (CYP2C19*5) mutations in Caucasians. In the present study, we genotyped 536 healthy unrelated Koreans for functionally defective alleles, CYP2C19*2, CYP2C19*3, CYP2C19*4, and CYP2C19*5. Detection of the normal (CYP2C19*1) and defective alleles was performed by polymerase chain reaction/restriction enzyme analysis. The genomic DNA was isolated from peripheral blood. The allelic frequencies of the wild-type (CYP2C19*1) and CYP2C19*2 were 72.6% and 27.4%, and the wild-type (CYP2C19*1) and CYP2C19*3 were 85.1% and 14.9%, respectively. For each CYP2C19*2 and CYP2C19*3 the observed number of three genotypes were similar to those calculated in accordance with the Hardy-Weinberg equation. The frequencies of homozygotes for CYP2C19*2, CYP2C19*3 and compound heterozygotes were 9.7%, 2.8% and 4.2%, respectively. The mutants of CYP2C19 were identified in 36 subjects (16.7%). The mutated CYP2C19*4 and CYP2C19*5 alleles were not detected in this study. These results suggest that frequency of mutants of CYP2C19 in Koreans resembled the Orientals rather than Caucasians, and we founded the racial variability of the frequencies of the CYP2C19*4 and CYP2C19*5 alleles in the Orientals.

최근 6년간 연세의료원에서 경험한 한국인 안면골 골절에 대한 임상적 연구

권준호,이충국,이의웅,민우석,윤중호,박형식 大韓顎顔面成形外科學會 1989 Maxillofacial Plastic Reconstructive Surgery Vol.11 No.1

This is a series of continuing research on facial bone fractures of Koreans worked by Dept. of Oral and Maxillofacial surgery, Dental College of Yonsei University, Seoul, Korea, since 1972. The study was based on a series of 630 patients with facial bone fractures treated as in patient at Yonsei Medical Center, Yonsei University, during the period of Jan. 1982 through Dec, 1987. The results obtained are as follows: 1. The ratio of Men to Women was 4.3 : 1, and admissions for facial bone fractures have been increased year after 1984. 2. The age frequency was highest in the third decade(38.3%). and fourth, second, fifth decade in orders. 3. The traffic accident was the most frequent cause of facial bone fractures(51.3%). 4. The most common location of facial bone fractures was the Mandible(35.3%), and Zygoma complex(29.8%), Nasal bone(15.0%), Maxilla(11.0%) were next in order of frequency. 5. In 291 patients of Mandible fractures, 226(77.7%) had fractures only in Mandible and 65(22.3%) had another facial bone fractures. The most frequent fracture site of mandible was the Symphysis(43.0%) and Angle(22.4%), and Simple fracture was the most frequent in type of fracture(66.9%). Intermaxillarty fixatin & Open reduction was major method of treatment(36.9%). 6. In 394 patients of Midface fractures 323(82.0%) had fractures only in Midface and 71(18.0%) had another facial bone fractures. The most frequent site of Midface fractures was zygoma complex & zygomatic arch(42.7%), and Simple fracture was the most common type of fractures. Observation(Maxilla :44.2%, Zygoma :51.0%) and Open Reduction(Maxilla :20.0%. Zygoma :23.5%) were the major method of treatment. 7. The frequency of Nasal bone fracture was about 1/5 of Midface fractures, and Closed Reduction(42.2%) was the major method of treatment. 8. The complication was reported in only 16 patients, and Malunion was the major complication. 9. Head(44.4%), Lower extrimities(14.5%) and Eye(12.3%) were injured commonly with facial bone fractures. 10. The elapsed time from injury to hospital was within 24 hours in 73.8% of patients, however 15.5% of patients arrived the hospital 72 hours after injury.

Three-piece basal archwire를 이용한 치열 정중선 불일치의 교정치료

김석준,손우성 대한치과교정학회 2000 대한치과교정학회지 Vol.30 No.4

경미하거나 중등도의 골격성 비대칭을 동반한 치열 정중선 불일치를 치료할 때 진단시 간과한 경우 교정치료의 마무리시기에 발견하여 치료기간이 더 길어지거나 만족스럽지 못한 결과를 초래하게 된다. 이때 비대칭 악간 고무줄을 사용한 통상적인 방법으로 장기간 치료하면 교합평면이 변화되거나 치아가 경사 이동되는 등 여러 가지 부작용들이 발생할 수 있다. 이를 예방하기 위해 초진시 부터 세심한 진단과 정확한 역학의 적용이 필요하다. Dr. Burstone이 제안한 three-piece basal archwire는 posterior anchorage unit, anterior segment와 intrusion arch로 구성된다. Three-piece basal archwire는 전치부 함입과 후방견인을 동시에 도모할 수 있으며, 기울어진 전치부 교합평면의 개선도 가능하다. 편측으로만 견인력을 적용하여 치열 정중선을 개선할 때 절치가 경사이동되는 것을 방지하기 위해 Three-piecebasal archwire를 응용하여 견인하는 방향의 반대측에 모멘트를 부가하면 절치의 편측 치체 이동을 도모할 수 있다. 이러한 방법으로 치열 정중선 불일치를 개선한 치료 증례를 살펴보고자 한다. At the finishing stage, the use of asymmetric elastics to treat mild skeletal and dental midline discrepancies often creates several side effects such as canted occlusal plane, tipped incisors and unesthetic results. This report presents the clinical cases with midline discrepancies, following a differential diagnosis, optimal mechanics, and considerations in treatment. Differential diagnosis and treatment mechanics with three-piece basal archwire can obtain predictable midline correction with minimal side effects.

하악골 회전성장 양상에 따른 골격성 Ⅲ급 부정교합자의 이부 및 상하악 절치부의 형태적 특성에 관한 연구

김석준,손우성 대한치과교정학회 1998 대한치과교정학회지 Vol.29 No.3

골격성 Ⅲ급 부정교합자의 하악골 회전성장 양상이 하악이부 및 상하악절치부의 형태와 어떠한 관련이 있는지 알아보고자 본 연구를 시행하였다. 하악 전돌의 악골부조화를 보이며 교정치료의 경험이 없는 골격성 Ⅲ급 부정교합자 성인 남녀 86명을 Skieller등이 하악골 회전성장 양상을 파악하기 위해 제안한 방법을 통해 전방회전성장군과 후방회전성장군으로 분류하여, 골결석 Ⅲ급 부정교합자에서 하악골 회전성장 양상에 따른 골격관계, 하악이부의 형태와 상하악절치의 위치에 관하여 분석한 결과 다음과 같은 결론을 얻었다. 1. 전방회전성장군에서 후방회전성장군에 비해 수평적인 두 개안면 골격관계에서 SNS, SNB가 모두 유의성 있게 크게 나타났다. 또한 수직적인 두 개안면 골격관계에 대해서는 모든 항목에서 차이가 있었다. 2. 하악이부 및 상하악절치부 형태와 하악골의 회전성장 양상 사이의 관계에서는 후방회전성장군에서 하악절치가 더 설측경사되고, 하악절치의 치조부 순설폭경이 좁으며 상악절치의 치조부에서 구개평면까지의 거리가 더 증가되었다. 3. 하악평면을 기준으로 계측한 symphsis ratio는 전방회전성장군과 후방회전성장군 사이에 유의한 차이가 없었다. 4. 하악골의 회전성장 양상과 하악이부 및 상하악절치부 형태에 대한 계층항목과의 상관분석에서, 후방회전성장 양상으로 성장할수록 overbite의 감소, 하악절치의 설측경사, 하악절치의 치조부 순설폭경 및 symphysis width의 감소가 나타났다. The aim of this study was to evaluate the morphology of the mandibular symphysis and anterior alveolar and skeletal relationship under the influence of the rotational growth pattern of mandible in skeletal Class Ⅲ malocclusion. A total of 86 untreated adult subjects were divided into two groups-forward rotational growth pattern group, backward rotational growth pattern group-according to the suggestion of Skieller et al. The antero-posterior position, vertical relationship, mandibular symphysis and anterior alveolar and skeletal relationship were assessed on lateral cephalometric radiographs. Mandibular sysphysis and anterior and skeletal relationship in each subject were studies and the following conclusions were drawn : 1. Concerning the antero-posterior position, forward rotational growth pattern group showed significantly larger SNA, SNB. Concerning the vertical relationship, all measurements showed statistically significant differences. 2. Forward rotational growth pattern group showed significantly larger IMPA, MnAD, backward rotational growth pattern group showed significantly larger MxABH. 3. There was no statistically significant difference in symphysis ratio to mandibular plane between forward and backward rotational growth pattern group. 4. In the correlative analysis of rotational growth pattern of mandible and mandibular symphysis, anterior alveolar and skeletal relationship, statistically significant correlations in overbite, IMPA, MnAD, symphysis width were showed.

골반내에 발생한 Proximal-type 유상피성 육종 1예

길준철,이상수,전병화,김성훈,손우석,목정은,박양순,강길현 대한부인종양 콜포스코피학회 2003 Journal of Gynecologic Oncology Vol.14 No.4

유상피성 육종은 매우 드문 악성 연조직 육종으로, 전형적인 경우들은 주로 젊은 남성의 수부, 전완부와 같은 신체의 원위부에 피하 혹은 심재성 피부 종괴로 발생하며, 조직학적 소견상 적은 비정형성을 나타내는 유상피성 세포와 방추형 세포의 증식에 의한 다발성 결절 형태의 배열을 보인다. 최근에 전형적인 유상피성 육종과 조직학적 유사성을 가지나 더 공격적인 형태인 proximal-type 유상피성 육종이 보고되었으며, proximal-type은 전형적인 유상피성 육종에 비하여 현저한 유상피성 세포의 발현과 매우 심한 비정형성을 나타내며, 세포가 매우 크고, 소포성 핵과 뚜렷한 핵소체를 보이며, 자주 rhabdoid 세포의 양상을 띈다. 임상적으로는 전형적인 형태에 비하여 호발 연령이 조금 늦고, 주로 체간부에, 특히 골반, 회음부, 생식기 등과 같은 심부에 발생하고, 더욱 공격적인 양상을 나타낸다. 저자들은 13세 소녀에서 원발부위를 알 수 없는, 골반내에 발생한 proximal-type 유상피성 육종 1예를 경험하여, 문헌 고찰과 함께 보고하는 바이다. Epithelioid sarcoma is a rare malignant soft-tissue sarcoma with an unknown histiogenesis, typically presenting as a subcutaneous or deep dermal mass lesion in the distal portions of the extremities of young adults. Recently, a more aggressive, so-called 'proximal-type' epithelioid sarcoma has been reported. In contrast to conventional epithelioid sarcoma, the proximal type is characterized by a predominantly large cell epithelioid cytomorphology, marked cytologic atypia, and frequent occurrence of rhabdoid features in most patients. Proximal-type epithelioid sarcoma has a predilection for appearing in the genitalia, especially the vulva, penis, pelvis and buttocks. Also this lesion appears to be somewhat more aggressive or at least metastasizes earlier than the conventional epithelioid sarcoma. We report a 13-year-old girl who presented with a buge mass filling the pelvic cavity which was painful, hard and fixed on palpation, and was radiologically diagnosed as a malignant germ cell tumors on the CT scan. The mass was surgically excised and pathologically proved to be an proximal-type epithelioid sarcoma of unknown origin.

하이브리드 외부가압 공기베어링에서 노즐 위치에 따른 부하지지력 특성

이득우,이종렬,황성철,이준석 한국공작기계학회 2000 한국공작기계학회 추계학술대회논문집 Vol.2000 No.-

Externally pressurized air journal bearing has been widely used in high-speed spindle system and precision machinery because of its characteristics such as substantially low frictional loss, low heat generation and averaging effect leading better running accuracy. But air journal bearing have a disadvantage of the low load capacity due to the low viscosity. In this paper. The air journal bearing design to overcome the defects of air bearing such as low stiffness and dimping coefficients was investigated theoretically.

고압 커패시터의 고장 분석을 통한 신뢰도 예측

양석준,김진우,신승우,이희진,신승훈,유동수,장석원 한국비파괴검사학회 2001 한국비파괴검사학회지 Vol.21 No.6

본 논문은 고압 커패시터의 고장분석과 신뢰성 예측 결과를 다루고 있다. 부품의 수명과 고장률을 예측하기 위해서 두 가지 방법으로 고장 모드와 고장 메커니즘을 연구하였다. 에폭시 수지로 성형된 고압 커패시터가 절연내압 시험 하에서 저항이 제로로 되는 고장에 대하여, 근본원인 고장분석 체계를 효과적으로 수립함으로써 고장 메커니즘의 원인을 분석하였다. 특히 세라믹-에폭시 계면에서의 절연파괴 고장 현상이 강조되었으며, 본 연구에서 얻어진 결과의 타당성은 마그네트론에 장착된 고압 커패시터의 열사이클 시험 수행에 의한 가속시험 결과로부터 입증되었다. 시험 결과들은 결함이 있는 로트를 신속히 규명하고 B10수명을 결정하는데 유용하게 사용할 수 있다. 또한, 유전체의 절연파괴에 대해서 부하-강도 간섭모델을 이용하여 고장률을 예측하였다. This paper presents a result of failure analysis and reliability evaluation for high voltage ceramic capacitors. The failure modes and failure mechanisms were studied in two ways in order to estimate component life and failure rate. The causes of failure mechanisms for zero resistance phenomena under withstanding voltage test in high voltage ceramic capacitors molded by epoxy resin were studied y establishing an effective root cause failure analysis. Particular emphasis was placed on breakdown phenomena at the ceramic-epoxy interface. The validity of the results in this study was confirmed by the results of accelerated testing. Thermal cycling test for high voltage ceramic capacitor mounted on a magnetron were implemented. Delamination between ceramic and epoxy, which might cause electrical short in underlying circuitry, can occur during curing or thermal cycle. The results can be conveniently used to quickly identify defective lots, determine B10 life estimation each lot at the level of inspection, and detect major changes in the vendors processes. Also, thd condition for dielectric breakdown was investigated for the estimation of failure rate with load-strength interference model.

초음파 진동절삭을 이용한 평면 광도파로와 유리의 미세 홈 가공특성에 관한 연구

이준석,김병국,정융호,이득우 한국공작기계학회 2002 한국공작기계학회 춘계학술대회논문집 Vol.2002 No.-

Recent years, optical components' are widely used in optical communication industry for high speed and mass storage data processing. Micro grooving of planar lightwave circuit and glass, those are widely used in optical component, are realized by polycrystalline diamond tool with ultrasonic vibration. To know the characteristics of brittle materials cutting, ultrasonic vibration cutting tool and machining system are built for the experiment. Grooving on planar lightwave circuit and glass experiments are performed and their shape are measured by photograph with microscope. It reveals that better groove shape with low chipping of planar lightwave circuit and glass are obtained by micro grooving machining with ultrasonic vibration. These experiments are considered as a possibility to the micro grooving of optical communication components.

서울의 Penicillinase Producing Neisseria gonorrhoeae 발생빈도(1998)

김재홍,김준호,반재용,이정우,황성주,정준규,정성태,강진문,조흔정,홍창의,정혜신,이한승,김이선,이봉길,이종호,선영우,한기덕,윤성필,이성훈,안종성,박석범,문승현,조항래,김형섭,류지호,황재영,박준홍,손상욱 한양대학교 의과대학 2001 한양의대 학술지 Vol.21 No.1

In recent years, gonorrhea has been pandemic and remains one of the most common STDs in the world, especially in developing countries. For the detection of a more effective therapeutic regimen and assessing the prevalence of Penicillinase Producing Neisseria gonorrhoeae(PPNG), we have been trying to study the patients who have visited the Venereal Disease Clinic of Choong-Ku Public Health Center in Seoul since 1980 by menas of the chromogenic cephalosporin method. In 1998, 93 strians of N. genorrhoeae were isolated, among which 60(64.5%) were PPNG. The prevalence of PPNG in Seoul, which had been decreased to 39% in 1996 after a peak of 74.3% in 1993, is increased to 64.5% in 1998.