회원작품 - 레인보우 유치원

최재형,Choi, Jae-hyeong 대한건축사협회 2015 建築士 Vol.2015 No.6

회전익 항공기 전륜착륙장치 단속거동 현상 개선연구

최재형,장민욱,이윤우,윤종진,Choi, Jae Hyung,Chang, Min Wook,Lee, Yoon-Woo,Yoon, Jong Jin 한국항공운항학회 2017 한국항공운항학회지 Vol.25 No.3

The Nose Landing Gear(NLG) of Rotary Wing Aircraft is an essential equipment in Landing System for pilot to perform a flight mission. It supports the fuselage at ground and absorbs the impact from the ground when landing, thereby, these functions sustain operational capability for pilot and crew. However, the A aircraft caused stick-slip behavior when it was stationed on the ground. Therefore, this paper summarizes pilot comment in operation which are classified by cause of occurrence and the troubleshooting process about each comment. It also describes design improvements which was derived from troubleshooting and suggests verification results of flight test.

전도냉각형 고온초전도 에너지저장장치의 전기적 특성

최재형,곽동순,천현권,김해종,김상현,Choi, Jae-Hyeong,Kwag, Dong-Soon,Cheon, Hyeon-Gweon,Kim, Hae-Jong,Kim, Sang-Hyun 한국전기전자재료학회 2007 전기전자재료학회논문지 Vol.20 No.2

The conduction-cooled HTS SMES is operated in cryogenic and high vacuum condition. Thus, Insulation design at cryogenic temperature and high vacuum is a key and an important element that should be established to accomplish miniaturization that is a big advantage of HTS SMES. However, the behaviors of insulators for cryogenic conditions in vacuum are virtually unknown. Therefore, we need active research and development of insulation concerning application of the conduction-cooled HTS SMES. Therefore, in this study, we experimented about insulation characteristic high vacuum and cryogenic similar to driving condition of SMES system. Also, investigated about insulation characteristic of suitable some materials to insulator for conduction-cooled HTS SMES. As this results, we possessed basis data for insulation materials selection and insulation design for development of 600 kJ class conduction-cooled HTS SMES.

위암조직에서의 MAGE 유전자 발현

최재형,이상호,Choi, Jae-Young,Lee, Sang-Ho 대한위암학회 2005 대한위암학회지 Vol.5 No.3

목적: 정상세포와는 달리 종양세포에서만 비교적 특이적으로 발현되는 것을 tumor specific antigens이라고 하며 대표적인 것은 악성흑색종에서 처음 발견된 MAGE (melanoma antigen)가 있다. 위암조직에서의 MAGE subtype의 발현율은 약 $20{\sim}40%$ 정도로 알려져 있는데 진행성 위암은 전체적으로 예후가 불량하기 때문에 면역치료법과 같은 새로운 치료법을 고려해 볼 수 있다. 본 연구에서는 술 후에 얻은 정상 및 암 조직에서의 MAGE의 발현정도를 각 subtypes에 공통으로 존재하는 유전자를 Primers로 이용하여 조사하였다. 대상 및 방법: 내시경에서 진행성 암으로 진단된 후 수술받은 환자 53명을 대상으로 하였으며, 수술 중 절제된 위에서 정상조직과 암 조직을 얻어 $-70^{\circ}C$에서 보관하였다. 환자는 남자가 35명, 여자가 18명이었고 이들의 평균 연령은 57세였다. 보관된 조직에서 m-RNA를 분리한 후 RT-PCR과 nested PCR로 MAGE의 발현여부를 알아보았다. 기존에 알려진 MAGE gene의 subtypes에 공통으로 존재하는 oligonucleotides를 일차 primers로 이용하여 증폭시켰다. 그 후 또 다른 primers를 이용한 nested RT-PCR을 시행하여 각 조직에서의 발현율을 조사하였다. 결과: 위암환자에서 53예의 암조직 중 13개(24.5%)에서 MAGE gene이 양성으로 나왔고 정상조직에서는 MAGE gene이 모두 음성이었다. 위암의 조직형, ABO type, CEA, CA19-9와 cancer의 위치와는 상관관계가 없었다. 결론: 위암환자의 $20{\sim}30%$에서 MAGE gene이 발현되었으며, 이에 MAGE gene을 이용한 면역치료법의 시도가 필요 할 것으로 생각한다. Purpose: Among tumor-associated antigens, MAGE (melanoma antigen) was named as cancer/testis specific antigens because they are detected exclusively in the testis or cancer cells, including gastric carcinomas. Due to the elicitation of autoimmunitiy to tumors by these antigens either in vitro or in vivo and their tumor specificity, these antigens, thus, appear to be potential targets for tumor-specific immunotherapy. Materials and Methods: The fresh tumor tissue and normal gastric tissue samples were obtained from resected surgical specimens in 53 patients with gastric carcinomas. From the obtained cells, total cellular mRNA was extracted, and RT-PCR and nested PCR were run in 30 and 35 cycles respectively, with two different kinds of primers specially designed to detect six subtypes of MAGE DNA simultaneously. Results: In the 53 normal tissue, there was no expression of MAGE, but in the 53 cancer tissues, MAGE was expressed in 13 tissues (24.5%). Our data did not exhibit any correlation with the expression of the MAGE gene and clinicopathological factors. Conclusion: In our data, since 24.5% of gastric cancer tissues expressed MAGE, it should become possible to immunize a significant proportion of patients with advanced gastric carcinomas against the antigens encoded by these genes, provided that more antigenic peptides encoded by the genes of the MAGE family can be identified in the near future. (J Korean Gastric Cancer Assoc 2005;5:180-185)

SiAlON 원료분말제조를 위한 분무건조 과립분말의 형상과 크기에 미치는 공정변수효과

최재형,이소율,한윤수,이성민,남산,김성원,Choi, Jae-Hyeong,Lee, Soyul,Han, Yoonsoo,Lee, Sung-Min,Nahm, Sahn,Kim, Seongwon 한국재료학회 2017 한국재료학회지 Vol.27 No.12

SiAlON-based ceramics are some of the most typical ceramic materials used as cutting tools for HRSA(Heat Resistant Super-Alloys). SiAlON can be fabricated using ceramic processing, such as mixing, granulation, compaction, and sintering. Spray drying is a widely-used method for producing a granular powder of controlled morphology and size with flowability. In this study, we report a systematic investigation aimed at optimizing spherical granule morphology by controlling spray-drying parameters such as gas flow and feed rate. Before spray drying, the viscosities of the raw material slurries were also optimized with the amount of dispersant added.

SiAlON의 절삭성능에 미치는 소결조제와 조성의 영향에 대한 연구

최재형,이성민,남산,김성원,Choi, Jae-Hyeong,Lee, Sung-Min,Nahm, Sahn,Kim, Seongwon 한국분말야금학회 2019 한국분말재료학회지 (KPMI) Vol.26 No.5

SiAlON ceramics are used as ceramic cutting tools for heat-resistant super alloys (HRSAs) due to their excellent fracture toughness and thermal properties. They are manufactured from nitride and oxide raw materials. Mixtures of nitrides and oxides are densified via liquid phase sintering by using gas pressure sintering. Rare earth oxides, when used as sintering additives, affect the color and mechanical properties of SiAlON. Moreover, these sintering additives influence the cutting performance. In this study, we have prepared $Yb_{m/3}Si_{12-(m+n)}Al_{m+n}O_nN_{16-n}$ (m = 0.5; n = 0.5, 1.0) ceramics and manufactured SiAlON ceramics, which resulted in different colors. In addition, the characteristics of the sintered SiAlON ceramics such as fracture toughness and microstructure have been investigated and results of the cutting test have been analyzed.

고온가압소결을 이용한 YSZ-TiC 세라믹스 복합체의 제조와 특성

최재형,최지영,김성원,Choi, Jae-Hyung,Choi, Ji-Young,Kim, Seongwon 한국분말재료학회 (*구 분말야금학회) 2021 한국분말재료학회지 (KPMI) Vol.28 No.5

Zirconia has excellent mechanical properties, such as high fracture toughness, wear resistance, and flexural strength, which make it a candidate for application in bead mills as milling media as well as a variety of components. In addition, enhanced mechanical properties can be attained by adding oxide or non-oxide dispersing particles to zirconia ceramics. In this study, the densification and mechanical properties of YSZ-TiC ceramic composites with different TiC contents and sintering temperatures are investigated. YSZ - x vol.% TiC (x=10, 20, 30) system is selected as compositions of interest. The mixed powders are sintered using hot pressing (HP) at different temperatures of 1300, 1400, and 1500℃. The densification behavior and mechanical properties of sintered ceramics, such as hardness and fracture toughness, are examined.

혐기성 발효에 의한 다시마 추출물로부터 휘발성 유기산 제조

최재형(Jae Hyung Choi),송민경(Min Kyung Song),전병수(Byung Soo Chun),이철우(Chul Woo Lee),우희철(Hee Chul Woo) 한국청정기술학회 2013 청정기술 Vol.19 No.2

본 연구에서는 거대 갈조류 대표종인 다시마(Saccharina japonica)로부터 물리화학적 전처리 방법, 미생물 접종비율, 다시마 추출물의 농도 및 pH 조건에 따른 휘발성 유기산(volatile fatty acids, VFAs) 생산 가능성 확인과 생산 효율을 평가하고자 하였다. 물리화학적 전처리 방법에 따른 휘발성 유기산의 최대 농도는 황산, 아임계수, 지질 추출 후 아임계수 전처리 순으로 나타났다. 황산 전처리 방법에서 미생물 접종비율(유효용적(WV)/미생물 부피(M) = 10~30), pH (6.0~7.0) 및 다시마 추출물의 농도(18.0~72.0 g/L)의 혐기성 발효 조건에 따른 휘발성 유기산 생성 농도에 미치는 영향을 확인한 결과, 발효 온도 35℃, 미생물 접종비율 15, pH 7.0, 발효시간 372시간에서 다시마 추출물의 농도가 18.0, 36.0, 54.0, 72.0 g/L일 때, 휘발성 유기산의 최대 농도가 각각 9.8, 13.9, 18.6, 22.3 g/L로 확인되었다. 생산된 휘발성 유기산의 조성은 pH가 높을수록 아세트산과 프로피온산의 생산 비율이 높았으며, pH가 낮을수록 부티르산의 비율이 높게 확인되었다. 생산된 저농도의 휘발성 유기산은 농축 및 분리공정과 연계하여 향후 기초화학 원료와 바이오연료 등으로 사용될 수 있으므로, 기존 화석연료의 대체에너지 생산에 기여할 수 있을 것으로 기대된다. Volatile fatty acids (VFAs) production from marine brown algae, Saccharina japonica, was investigated in anaerobic dark fermentation. In order to evaluate the VFAs productivity, various experimental parameters (i.e., physicochemical pre-treatment, microorganism inoculation ratio, substrate concentration, and pH) were evaluated. According to the physicochemical pre-treatment methods, the maximum concentrations of VFAs were obtained in the order of sulfuric acid, subcritical water and subcritical water with lipid-extraction. Also, we investigated the operating parameters such as microorganism inoculation ratio (MV/M = 10 to 30), the substrate concentration (18.0 to 72.0 g/L) and pH (6.0 to 7.0) in sulfuric acid pre-treatment method. When the substrate concentrations were 18.0, 36.0, 54.0 and 72.0 g/L at 35 ℃, microorganism inoculation ratio 15, pH 7.0 for 372 hours, the maximum concentrations of VFAs were respectively 9.8, 13.9, 18.6 and 22.3 g/L. The change in VFAs concentrations was detected that acetic- and propionic acids increased according to increasing pH, while the butyric acid increased with decreasing pH. The VFAs obtained from concentration and separation process may be used as basic chemistry materials and bio-fuel, and they will expect to produce alternative energy of fossil fuel.

회전익 항공기 안전 확보를 위한 주륜완충장치 결함 개선연구

최재형(Jae Hyung Choi),장민욱(Min Wook Chang),임현규(Hyun-Gyu Lim),이제석(Je Suk Lee) 한국항공우주학회 2017 韓國航空宇宙學會誌 Vol.45 No.6

회전익 항공기에 적용된 주륜완충장치는 착륙계통 장비로서 조종사의 임무 수행에 핵심적인 장비이다. 주륜완충장치는 항공기가 지상에 있을 때 동체를 지지해주며 착륙 시 지면으로부터 오는 충격을 흡수함으로서 조종사 및 병력의 작전 운용능력을 만족시킨다. 그러나 A 항공기 지상 계류 시 항공기의 비대칭 현상과 누유 현상이 발생되었다. 따라서 본 논문에서는 주륜완충장치의 운용 시 발생한 결함사항을 발생원인 별로 분류하고, 각 지적 사항에 대한 고장탐구 수행과정을 정리하였다. 또한, 고장탐구 내용을 바탕으로 도출한 설계개선 사항과 개선사항에 대한 검증 결과를 함께 기술하였다. The Main Landing Gear(MLG) of Rotary Wing Aircraft is an essential equipment in Landing System for pilot to perform a flight mission. It supports the fuselage at ground and absorbs the impact from the ground when landing, thereby, these functions sustain operational capability for pilot and crew. However, the A aircraft caused asymmetry and leakage hydraulic when it was stationed on the ground. Therefore, this paper summarizes pilot comments in operation which are classified by cause of occurrence and the troubleshooting process about each comment. It also describes design improvements which was derived from troubleshooting and suggests verification results of flight test.

구리 촉매상에서 글리세롤의 산화 카르보닐화 반응에 의한 글리세롤 카보네이트 합성

최재형(Jae Hyung Choi),이상득(Sang Deuk Lee),우희철(Hee Chul Woo) 한국청정기술학회 2013 청정기술 Vol.19 No.4

본 연구에서는 환경친화적인 측면을 고려하여 제철소 및 석유화학공장에서 많이 발생되는 부생가스인 일산화탄소와 산소를 이용하여 글리세롤로부터 글리세롤 카보네이트를 합성하는 공정에 대하여 연구하였다. 글리세롤의 산화성 카르보닐화 반응활성은 회분식 고압반응기에서 다양한 금속촉매(Cu, Pd, Fe, Sn, Zn, Cr계)에 대한 영향과 산화제, 일산화탄소와 산소의 몰 비율, 촉매량, 용매의 종류, 반응 온도 및 시간, 탈수제 첨가에 대한 반응조건들을 확인하였다. 특히, 염화구리 촉매가 우수한 반응 활성을 나타내었고, 니트로벤젠 용매상에서 글리세롤:일산화탄소:촉매의 몰 비율이 1:3:0.15, 일산화탄소:산소의 몰 비율이 2:1, 전체 반응압력이 30 bar, 반응온도 413 K, 반응시간 4시간 동안 염화구리(I)와 염화구리(II) 촉매에 대한 수율은 각각 최대 44%와 64%를 보였다. 이러한 결과로부터 구리촉매의 산화수에 따라 반응활성이 큰 차이가 보이는 것을 확인하였으며, 산화제로서의 산소의 역할은 글리세롤의 카르보닐화 반응 후 산화반응이 수반되어 부생성물인 물을 생성하는데 중요한 역할을 하고 있는 것을 확인할 수 있었다. In environmental friendly aspects, the synthesis of glycerol carbonate from glycerol using carbon monoxide and oxygen gases which were produced in petrochemical plants was studied. The oxidative carbonylation of glycerol under batch reaction system was performed on parameter conditions such as effect of various metals (Cu, Pd, Fe, Sn, Zn, Cr), oxidizing agents, mole ratio of carbon monoxide to oxygen, catalyst amount, solvent types, reaction temperature and time and dehydrating agents. In particular copper chloride catalysts showed the excellent activities, and the glycerol carbonate yields over CuCl and CuCl2 catalysts were the maximum of 44% and 64%, respectively at the following reaction conditions: solvent as nitrobenzene, mole ratio of 1:3:0.15 (glycerol:carbon monoxide:catalyst), mole ratio of 2:1 (carbon monoxide:oxygen), the total pressure of 30 bar at 413 K for 4 hr. It was found that reactivity were significantly different depending on the oxidation number of Cu catalysts, and oxygen plays an important role as oxidizing agents in producing H2O during oxidation reaction after carbonylation of glycerol.