CoMo / 실리카 - 알루미나에 제올라이트를 혼합한 촉매상에서 감압 잔사유의 수소화 분해 반응

최진우,최우석,이경환,하백현 ( Jin Woo Choi,Woo Suk Choi,Kyoung Hwan Lee,Baik Hyon Ha ) 한국화학공학회 1994 Korean Chemical Engineering Research(HWAHAK KONGHA Vol.32 No.5

The catalysts of CoMo/silica-alumina and those mixed with steamed HY and H-mordenite were used for hydrocracking of a vacuum residue in a high-pressure batch reactor. The catalysts were characterized by temperature-programmed desorption of ammonia and nitrogen adsorption. The catalysts containing the zeolite had the more acid sites and two kinds of pore size: macropore(about 600 Å) of silica-alumina and secondary pore(about 40 Å) of the zeolite. The catalyst containing HY improved the cracked yield and selectivity of light oil(C_5-C_9). However, the catalyst containing the H-mordenite which have not a secondary pore showed lower activity, but slightly increased the conversion of asphaltene than that with HY. Therefore, the primary cracking of vacuum residue occurred in the large pore of silica-alumina and then the cracking continued in the secondary pore of zeolite and finally in zeolite micropore. It was found in conclusion that the control of the secondary pore in zeolite played a important role in the hydrocracking of the vacuum residue.

FRP-콘크리트 합성말뚝의 개발

최진우,주형중,남정훈,윤순종,Choi, Jin-Woo,Joo, Hyung-Joong,Nam, Jeong-Hun,Yoon, Soon-Jong 한국복합신소재구조학회 2010 복합신소재구조학회논문집 Vol.1 No.2

이 논문에서는 기존의 CFFT(Concrete Filled FRP Tube) 복합재 말뚝의 휨강성을 확보하기 위한 새로운 복합재 말뚝형식을 제안하였다. 기존의 CFFT 복합재 말뚝은 필라멘트와인딩 공정으로 제작한 FRP를 사용하기 때문에, 압축력이 편심재하될 경우 휨거동에 대한 안전성을 확보하기 위해 철근 등 별도의 보강재를 필요로 한다. 이 연구에서는 별도의 보강재 없이 휨거동에 대한 저항성을 확보하기 위하여 펄트루젼 방식으로 제작된 FRP를 CFFT 외부에 원주방향으로 부착시킨 FRP-콘크리트 합성말뚝(Hybrid CFFT, HCFFT)을 제안하였다. 이 논문은 HCFFT의 구조적 거동을 검토하기 위한 연구의 일부로서, HCFFT에 사용되는 필라멘트와인딩 FRP의 역학적 특성을 알기 위한 실험을 실시하였다. 또한, 기존 연구 결과를 참조하여 HCFFT의 압축강도를 추정하였으며, 유한요소해석을 통해 얻은 결과와 비교분석하였다.

복합신소재를 사용한 거푸집

최진우,윤순종,Choi, Jin-Woo,Yoon, Soon-Jong 한국복합신소재구조학회 2012 복합신소재학회논문집 Vol.3 No.1

Macrobenthos Community in Keum-Mankyung-Dongjin Estuaries and its Adjacent Coastal Region, Korea

최진우,고철환,CHOI, JIN-WOO,KOH, CHUL-HWAN The Korean Society of Oceanography 1994 韓國海洋學會誌 Vol.29 No.3

Macrobenthic fauna in three Keum-Mankyung-Dongjin Estuaries and their nieghbouring coastal region in the west coast of Korea were sampled as 39 stations with van Veen grab to describe the distribution patterns of macrobenthos. Total 61 taxa from 10 faunal taxonomic groups and 5,636 individuals were collected. Abundance, species number, and faunal composition varied among three estuaries and coastal region. Dominant species from estuaries were similar to each other, but different from those of coastal region. Dominant species in estuarine regions were Prionospio cirrifera, potamocorbula amurensis. Nephtys californiensis, Glycera chiron and Glycinde sp, those from coastal area were Mactra chinensis. Magelona japonica, Owenia fusiformis. Anaitides Korean and Nephtys polybranchia. Two most dominant species in estuaries, Potamocorbula amanuensis and Prionospio cirrifer were not found elsewhere in Korean waters. The patchy distribution of dominant species and low species richness were reflected in the low species diversity Filter feeders were a major component in estuaries. High proportion of carnivores and low percentage of subsurface deposit feeders seemed to be a typical trophic composition in the study area. the distribution pattern of macrobenthos was related with the salinity and sediment types.

디지털 방사선영상 시스템의 기본적 원리

최진우,이원진,Choi, Jin-Woo,Yi, Won-Jin 대한영상치의학회 2010 Imaging Science in Dentistry Vol.40 No.4

Digital radiographic systems allow the implementation of a fully digital picture archiving and communication system (PACS), and provide the greater dynamic range of digital detectors with possible reduction of X-ray exposure to the patient. This article reviewed the basic physical principles of digital radiographic imaging system in dental clinics generally. Digital radiography can be divided into computed radiography (CR) and direct radiography (DR). CR systems acquire digital images using phosphor storage plates (PSP) with a separate image readout process. On the other hand, DR systems convert X-rays into electrical charges by means of a direct readout process. DR systems can be further divided into direct and indirect conversion systems depending on the type of X-ray conversion. While a direct conversion requires a photoconductor that converts X-ray photons into electrical charges directly, in an indirect conversion, lightsensitive sensors such as CCD or a flat-panel detector convert visible light, proportional to the incident X-ray energy by a scintillator, into electrical charges. Indirect conversion sensors using CCD or CMOS without lens-coupling are used in intraoral radiography. CR system using PSP is mainly used in extraoral radiographic system and a linear array CCD or CR sensors, in panoramic system. Currently, the digital radiographic system is an important subject in the dental field. Most studies reported that no significant difference in diagnostic performance was found between the digital and conventional systems. To accept advances in technology and utilize benefits provided by the systems, the continuous feedback between doctors and manufacturers is essential.

국내 의료기관에서 측방두부규격방사선촬영시 임상에서의 촬영조건 및 환자 선량

최진우,Choi, Jin-Woo 대한영상치의학회 2010 Imaging Science in Dentistry Vol.40 No.4

Purpose : To survey the radiographic examination protocol for lateral cephalometric radiographic examinations and to measure their patient doses in Korea and to compare the dose according to the size of hospital, the type of image receptor system, and the installation duration. Materials and Methods : The radiographic examination protocols (kVp, mA, and exposure time) for lateral cephalometric radiography were surveyed with 61 cephalometric radiographic equipments and their patient dose-area product (DAP) measured with a DAP meter (DIAMENTOR M4-KDK, PTW, Freiburg, Germany) for 51 cephalometric radiographic equipments. The radiographic examination protocols and patient doses were compared according to the size of hospital (university dental hospital, dental hospital, and dental clinic), the type of image receptor system (film-based, DR and CR type) and the installation duration, respectively. SPSS 12.0.1 for Windows (SPSS Inc., Chicago, USA) was used for independent t-test and ANOVA test. Results : The average protocols were 77.0 kVp, 12.7 mA, 6.2 second for cephalometric radiography. The average patient dose (DAP) was $128.0mGy\;cm^2$ and 3rd quartile dose (DAP) $161.1mGy\;cm^2$ for cephalometric radiography for adult male. There was no statistically significant difference at average patient DAP according to the size of hospital, the type of image receptor system, and the installation duration, repectively. Conclusion : The average patient dose was $128.0mGy\;cm^2$ and the third quartile patient dose $161.1mGy\;cm^2$ for lateral cephalometric radiography for adult male in Korea.

MRI findings of a huge cystadenocarcinoma of the palate

최진우,Choi, Jin-Woo Korean Academy of Oral and Maxillofacial Radiology 2010 Imaging Science in Dentistry Vol.40 No.4

Cystadenocarcinoma of the salivary glands is a very rare, slow growing, and low-grade malignant neoplasm. It is characterized by predominantly cystic growth with or without the intraluminal papillary component. However, it lacks of any additional specific histopathologic features that characterize other types of salivary carcinomas showing cystic growth. Therefore, definite diagnosis of the cystadenocarcinoma is difficult and it is often misdiagnosed. It is conceptually the malignant counterpart of the benign cystadenoma. We present a cystadenocarcinoma on the palate of a 49-year-old man with special emphasis on magnetic resonance imaging.

직교이방성 판의 좌굴 및 압축재의 국부좌굴에 대한 해석적 연구

최진우,이강연,박정환,윤순종,Choi, Jin-Woo,Lee, Kang-Yeon,Park, Jung-Hwan,Yoon, Soon-Jong 한국복합신소재구조학회 2012 복합신소재구조학회논문집 Vol.3 No.1

In this paper, we present the analytical study results pertaining to the buckling of the orthotropic plates and local buckling of structural compression members composed of orthotropic plate components. Fiber reinforced polymeric plastic (FRP) materials, have many advantages over conventional structural materials such as steel and concrete. The advantages of the FRP materials are high specific strength and stiffness, high corrosion resistance, right weight, etc. Among the various manufacturing methods, pultrusion process is one of the best choices for the mass production of structural plastic members. Since the major reinforcing fibers are placed along the axial direction of the member, this material is usually considered as an orthotropic (tranversely isotropic, more specifically) material. However, pultruded fiber reinforced plastic structural members have low modulus of elasticity and are composed of orthotropic thin plate components the members are prone to buckle. Therefore, stability is an important issue in the design of the pultruded FRP structural members. In this paper, the buckling of orthotropic plates and the local buckling of pultruded FRP structural members are investigated by following the previous research results and the local buckling strength of the member produced in the domestic manufacturer is found.

수상 부유식 태양광발전 구조물의 구조적 성능 평가

최진우,서수홍,주형중,윤순종,Choi, Jin Woo,Seo, Su Hong,Joo, Hyung Joong,Yoon, Soon Jong 대한토목학회 2014 대한토목학회논문집 Vol.34 No.5

In recent years, numerous environmental problems associated with the excessive use of fossil fuel are taking place. For an alternative energy resource, the importance of renewable energy and the demands of facilities to generate renewable energy are continuously rising. To satisfy such demands, a large number of photovoltaic energy generation structures are constructed and planned with large scale. However, because these facility zones are mostly constructed on land, some troubles are occurred such as rising of construction cost due to the cost of land use, environmental devastation, etc. To solve such problems, the floating type photovoltaic energy generation system using FRP members have been developed in Korea. FRP members are recently available in civil engineering applications due to many advantages such as high strength, corrosion resistance, light weight, etc. and they are suitable to fabricate the floating structures because of their material properties. In this study, the analytical and experimental investigations to evaluate the structural performance of floating PV generation structure and SMC FRP vertical member which is used to fabricate the structure were conducted. The static and dynamic performances of floating PV generation structure are evaluated through the FE analysis and the experiment, respectively. Moreover, the structural safety evaluation and buckling analysis of SMC FRP vertical compression member are also conducted by the FE analysis, and the structural behavior of SMC FRP member under compression and pullout is investigated by the experiments. From this study, it was found that the structural system composed of pultruded FRP and SMC FRP members are safe enough to resist externally applied loads.

단면 내 응력분포를 고려한 I형 및 Box형 단면의 PFRP 압축재의 설계

최진우,김재욱,주형중,윤순종,Choi, Jin-Woo,Kim, Jae-Wook,Joo, Hyung-Joong,Yoon, Soon-Jong 한국복합신소재구조학회 2011 복합신소재구조학회논문집 Vol.2 No.1

Pultruded fiber reinforced polymeric plastic (PFRP) structural members may be one of attractive alternatives of the structural members in the civil engineering applications because of its many advantageous mechanical properties. However, they have relatively low modulus of elasticity and also cross-sections of structural shapes are composed of thin plate components such as flange and web. Therefore, structural stability is an important issue in the design of pultruded structural compression members. For the design of pultruded structural member under compression, buckling and post-buckling strengths of plate components may be taken into account. In the structural steel design following AISC/LRFD, in addition to the buckling strength, the nonuniform stress distribution in the section is incorporated with a form factor. In this paper, the form factor for the design of PFRP structural member under compression is investigated through the analytical study. Furthermore, the process for the determination of the form factor is suggested.