AC4A 알루미늄 합금의 주조특성에 미치는 미량 첨가원소의 영향

오승환,김헌주,Oh, Seung-Hwan,Kim, Heon-Joo 한국주조공학회 2017 한국주조공학회지 Vol.37 No.5

The effects of minor additives on the casting properties of AC4A aluminum alloys were investigated. Measurements of the cooling curve and microstructure observations were conducted to analyze the effects of Ti-B and Sr minor elements during the solidification process. A fine grain size and an increase in the crystallization temperature for the ${\alpha}-Al$ solution were evident after the addition of 0.1wt% Al-5%Ti-1%B additive. The modification effect of the eutectic $Mg_2Si$ phase with the addition of 0.05% Al-10%Sr additive was prominent. A fine eutectic $Mg_2Si$ phase and a decrease in the growth temperature of the eutectic $Mg_2Si$ phase were evident. Fluidity, shrinkage and solidification-cracking tests were conducted to evaluate the castability of the alloy. The combined addition of Al-5%Ti-1%B and Al-10%Sr additives showed the maximum filling length owing to the effect of the fine ${\alpha}-Al$ grains. The macro-shrinkage ratio increased, while the micro-shrinkage ratio decreased with the combined addition of Al-5%Ti-1%B and Al-10%Sr additives. The macro-shrinkage ratio was nearly identical, while the micro-shrinkage ratio increased with the addition of the Al-10%Sr additive. The tendency of the occurrence of solidification cracking decreased owing to the effect of the fine ${\alpha}-Al$ grains and the modification of the $Mg_2Si$ phase with the combined addition of Al-5%Ti-1%B and Al-10%Sr additives.

허혈후 칼슘 결핍 용액의 재관류가 적출 관류 기니픽 심근 세포에 미치는 영향에 관한 전자현미경적 관찰

오승환,김호덕,라봉진,Oh, Seung-Hwan,Kim, Ho-Dirk,Rah, Bong-Jin 한국현미경학회 1990 Applied microscopy Vol.20 No.1

The effect of calcium-free reperfusion for 5, 10, and 15 minutes, respectively, followed by continuous reperfusion with normal Tyrode solution containing 1.0mM calcium chloride, after global ischemia in the isolated perfused guinea pig heart by Langendorff techniques was examined with transmission electron microscope. Compared to the nomal Tyrode solution-perfused control hearts, the 5 minute calcium-free-reperfused hearts showed loss or thickening of Z lines, focal sarcolemmal disruption, mitochondrial swelling, clumping of chroma-tin, intracellular fluid accumulation, and some separation of cell junctions, especially the fasciae adherentes. These changes became more severe in the hearts of 10 minute calcium-free reperfusion. Subsarcolemmal larger bleb and near complete separation of cell junctions were noticed. In the 15 minute calcium-free-reperfused hearts, irreversible ultrastructural changes including contraction bands, biazrre mitochondria, and sarcolemmal destruction were widely distributed. The severity of myocardial changes were in accordance with the duration of calcium-free reperfusion. These changes indicate that calcium-free reperfusion regardless of its duration could not salvage the post-ischemic myocardium probably due to development of calcium paradox.

TG Osseotite 임플란트의 성공률에 대한 임상적 연구

오승환,민승기,채영원,Oh, Sung-Hwan,Min, Seung-Ki,Chae, Young-Won 대한악안면성형재건외과학회 2005 Maxillofacial Plastic Reconstructive Surgery Vol.27 No.1

The purpose of this study is to review the prognosis of the TG Osseotite implant(3i Co, USA) placed in partial edentulous area of oral cavity and to suspect the possible causes leading to failure. 124 TG Osseotite implants that had been inserted between 2000 - 2002 were followed up for 2 years(avg : 9.5 months) in function. Medical records, and radiographs were evaluated and analyzed by the over all success rate, gender and age factor, general disease, implant fixture length and diameter, implant site, bone density, and various surgical methods. Chi square test was used statistically. Of the 124 TG Osseotite implants, 9 implants(7.3%) were removed in early phase and 3 implants(2.4%) were in late phase. The cumulative survival rate was 90.2%. The failure of the TG Osseotite implant was closely related with the use of bone graft techniques such as sinus elevation or immediate implantation and not with the age, sex, general disease, implant site, bone density of implanted site. The failure of the TG Osseotite implant was well developed when it was the wide type of implant and it was inserted for single tooth replacement. The developement of peri-implantitis was the most important factor in the failure of the TG Osseotite implant.

미래 전력발전을 위한 종합전투실험체계 개념설계 연구

오승환,홍윤기,Oh, Seung-Hwan,Hong, Yoon-Gee 한국국방경영분석학회 2010 한국국방경영분석학회지 Vol.36 No.3

이 연구는 복합시스템 구축과 소요제기 결정에 활용하기 위하여 복합시스템 엔지니어링과 아키텍처 방법론으로 개발한 복합시스템 개념설계 모형을 제시하고 있으며, 모형의 검증은 Process Transition Map, 전문가 설문기법으로 수행하였다. 또한 미래 전력발전에 활용할 수 있도록 종합전투실험체계에 대한 개념설계를 프로세스 단계별 산출물을 작성하여 제시하였다. This Study proposes that a SoS(System of Systems) Conceptual Design Model which is developed for the SoS establishment, requirement and decision, utilizing SoS engineering and architecture methodology, and the Model performed with the Process Transition Map using subject matter expert survey. Establishing an Integrated Battle Experimentation System(IBES) for the future force development, the process product of IBES was conceptually designed using a SoS Conceptual Design Model.

악교정 수술 중 발생한 지연성 악성 고열증의 치료

오승환,민승기,권경환,조필귀,송윤강,Oh, Sung-Hwan,Min, Seung-Ki,Kwon, Kyung-Hwan,Jo, Pil-Kwy,Song, Yun-Kang 대한악안면성형재건외과학회 2005 Maxillofacial Plastic Reconstructive Surgery Vol.27 No.4

Malignant hyperthermia is a catastrophic, hypermetabolic syndrome that arises in susceptible individuals when they are exposed to certain inhalational anesthetics or muscle relaxants. It is characterized by hyperthermia, tachycardia, acidosis, and muscle rigidity. It has been noted that the majority of cases of malignant hyperthermia are fatal unless early diagnosis and treatment are performed. We experienced a 24 year old male Malignant hyperthermia presented for orthognathic surgery under $O_2-N_2O$-sevoflurane anesthesia without succinylcholine. Two half hours after induction, tachycardia developed and was followed by unstable blood pressure and hyperpyrexia. Anesthesia was terminated and vigorous emergency treatment was attempted. The patient was treated by the intravenous administration of dantrolene sodium. The diagnosis of an acute malignant hyperthermia reaction by clinical criteria can be difficult because of the nonspecific nature and variable incidence of many of the clinical signs and laboratory findings. So the malignant hyperthermia clinical grading scale is recommended for use as an aid to the objective definition of this disease. This clinical grading system provides a new and comprehensive clinical case definition for the malignant hyperthermia syndrome. We recently encountered a case of delayed malignant hyperthermia during sevoflurane anesthesia that was successfully treated by the intravenous administration of dantrolene sodium. In conclusion, exposure to sevoflurane should be avoided in patients thought to be susceprible to malignant hyperthermia.

청옥산 삼림식생에 관한 연구 - 식물사회학적 분석방법으로 -

오승환,윤충원,배관호,홍성천 ( Seung Hwan Oh,Chung Weon Yun,Kwan Ho Bae,Sung Cheon Hong ) 한국산림과학회 1998 한국산림과학회지 Vol.87 No.1

The Mt. Cheongok is located at the northern part of Kyungsangpookdo from 37°00` 00`` to 37°05` 00`` latitude and from 128°55` 00`` to 129°00` 00`` longitude. The altitude of the summit is 1,276.5m. This study was carried out to classify forest communities by the methods of Zurich-Montepellier schools. And, it also might be useful for selection of plant species, forest conservation, and prompting vegetation succession. The forest vegetation in Mt. Cheongok was classified into 12 communities, 4 groups, and 4 subgroups. Rhododendron micranthum subgroup of Pinus densiflora for. erecta community and Fraxinus mandshurica community were not found in cool temperate forest, southern zone yet. According to the coincidence method, Pines densiflora for. erecta community was mainly distributed from altitude 450m to 1,100m and from upper slope to ridge, and Quercus mongolica community was dominanced in the range of over altitude 700m. Pinus densiflora for. erecta community, distributed in upper slope and ridge, is judged to be maintained in the future. But Pinus densiflora for. erecta community, distributed in below middle slope, is judged to be changed into deciduous hardwood forest.

단일쇄 변이분절 항체의 분자유전학적 합성 및 임상적 이용

오승환,Oh, Seung Hwan 대한소아청소년과학회 2002 Clinical and Experimental Pediatrics (CEP) Vol.45 No.6

프라임, 테스트 등급 실리콘 웨이퍼의 표면 결함 특성

오승환,임현민,이동희,서동혁,김원진,김륜나,김우병,Oh, Seung-Hwan,Yim, Hyeonmin,Lee, Donghee,Seo, Dong Hyeok,Kim, Won Jin,Kim, Ryun Na,Kim, Woo-Byoung 한국재료학회 2022 한국재료학회지 Vol.32 No.9

In this study, surface roughness and interfacial defect characteristics were analyzed after forming a high-k oxide film on the surface of a prime wafer and a test wafer, to study the possibility of improving the quality of the test wafer. As a result of checking the roughness, the deviation in the test after raising the oxide film was 0.1 nm, which was twice as large as that of the Prime. As a result of current-voltage analysis, Prime after PMA was 1.07 × 10 A/cm² and Test was 5.61 × 10 A/cm², which was about 5 times lower than Prime. As a result of analyzing the defects inside the oxide film using the capacitance-voltage characteristic, before PMA Prime showed a higher electrical defect of 0.85 × 10¹² cm^-2 in slow state density and 0.41 × 10¹³ cm^-2 in fixed oxide charge. However, after PMA, it was confirmed that Prime had a lower defect of 4.79 × 10¹¹ cm^-2 in slow state density and 1.33 × 10¹² cm^-2 in fixed oxide charge. The above results confirm the difference in surface roughness and defects between the Test and Prime wafer.

열처리에 따른 Peroxo Titanium Complex 졸 용액 기반 TiN/TiO₂/FTO Resistive Random-Access Memory의 전기적 특성

임현민,이진호,김원진,오승환,서동혁,이동희,김륜나,김우병,Yim, Hyeonmin,Lee, Jinho,Kim, Won Jin,Oh, Seung-Hwan,Seo, Dong Hyeok,Lee, Donghee,Kim, Ryun Na,Kim, Woo-Byoung 한국재료학회 2022 한국재료학회지 Vol.32 No.9

A spin coating process for RRAM, which is a TiN/TiO₂/FTO structure based on a PTC sol solution, was developed in this laboratory, a method which enables low-temperature and eco-friendly manufacturing. The RRAM corresponds to an OxRAM that operates through the formation and extinction of conductive filaments. Heat treatment was selected as a method of controlling oxygen vacancy (V_O), a major factor of the conductive filament. It was carried out at 100 ℃ under moisture removal conditions and at 300 ℃ and 500 ℃ for excellent phase stability. XRD analysis confirmed the anatase phase in the thin film increased as the heat treatment increased, and the Ti³⁺ and OH- groups were observed to decrease in the XPS analysis. In the I-V analysis, the device at 100 ℃ showed a low primary SET voltage of 5.1 V and a high ON/OFF ratio of 10⁴. The double-logarithmic plot of the I-V curve confirmed the device at 100 ℃ required a low operating voltage. As a result, the 100 ℃ heat treatment conditions were suitable for the low voltage driving and high ON/OFF ratio of TiN/TiO₂/FTO RRAM devices and these results suggest that the operating voltage and ON/OFF ratio required for OxRAM devices used in various fields under specific heat treatment conditions can be compromised.

저소득층 청소년의 심리사회적 적응 결정요인

오승환(Seung Hwan Oh) 한국아동복지학회 2006 한국아동복지학 Vol.- No.21

본 연구에서는 빈곤가정의 청소년의 심리사회적 적응에 영향을 미칠 수 있는 요인을 적응유연성 관점에서 파악하고자 하는 연구이다. 빈곤청소년의 가지고 있는 위험요인과 보호요인이 적응에 미치는 영향을 발견하기 위하여 전국의 청소년자활지원관 25개소를 대상으로 설문조사를 실시하여 총 498명을 조사하였다. 심리사회적 적응요인 중 우울·불안에 영향을 미치는 요인을 살펴보면 성과 연령, 생활수준, 유능감, 가족 지지가 유의미한 영향을 미치고 있어 중요한 보호요인으로 나타났다. 비행에는 생활수준, 책임감과 유능감, 학교적응 교사지지 그리고 전문가 지지가 영향을 미치는 요인으로 나타나 비행행동을 감소시키는 보호요인으로 작용하고 있음을 보여준다. 이러한 결과에 비추어 빈곤청소년의 적응을 증진시키기 위해서는 보호요인으로 나타난 요인들을 증가시킬 수 있는 개입방법을 개발할 필요가 있다. The purpose of this study is to find the risk and protective factors associated with the adjustment of poor adolescents. Data came from the survey of 498 adolescents who are using self-sufficiency supporting centers. The results are as follows. First, for depression·anxiety problem, sex, living standard, locus of control, self-efficiency, and the support of family has effects on it. All variables except locus of control are identified as protective factor. Second, for deliquency problem, sex, living standard, sense of responsibility, self-efficiency, positive school attitude, the support of friend, teacher and professional has effects on it. All variables except the support of friend are identified as protective factor. This study confirmed that adjustment of poor adolescent was affected various risk and protective factors. In order to improve resilience of poor adolescent, risk factors have to be reduced and protective factors to be increased.