오일 내 공기혼입이 엔진베어링의 신뢰성에 미치는 영향

최재권,민병순(Jae-Kwon Choi),Byung-soon Min 한국자동차공학회 1994 한국자동차공학회 학술강연초록집 Vol.- No.-

고양이 송과체의 전자현미경적 연구

최재권,배춘상,오창석,이정헌,Choi, Jae-Kwon,Bae, Choon-Sang,Oh, Chang-Seok,Lee, Jung-Hun 한국현미경학회 1992 Applied microscopy Vol.22 No.1

Parenchyma of the cat pineal body consisted of pinealocytes and glial cells. The pinealocyte, predominant cell type, was characterized by having large mitochondria with pale matrix, abundant polyribosomes, moderately-developed Golgi apparatus, centrioles and occasional cilia. The pinealocyte had one thick and long cytoplasmic process at the one pole of the cell, and slender and shorter processes at the other pole, and in addition occasional short processes from the cell body. These processes contained longitudinally arranged microtubules, and a few mitochondria. Thick processes teminated as bulgings either in the intercellular process-rich area, or in the perivascular border which was formed by glial cell processes. These endings of pinealocyte processes had many small vesicles, mitochondria, and occasional dense bodies. Glial cells with abundant filaments of intermediate type and clear cytoplasmic matrix were fibrous astrocyte. Perikarya of the astrocytes had small and dense mitochondria, moderately developed Golgi apparatus, dense bodies and variable amount of intermediate filaments. Glial cell processes run through the intercellular spaces among the pinealocyte processes. Glial cell of protoplasmic type had no or a few filaments, but it had well-organized rough endoplasmic reticulum, dense mitochondria, well developed Golgi apparatus and many dense granules. Intercellular canaliculi formed by adjacent pinealocytes and glial cell processes were often noted. Within the parenchyma, sympathetic and parasympathetic axons and their endings were noted. These endings were present mostly in the intercellular spaces without having membrane specialization, however, in rare instances, ending with small clear and dense cored vesicles, and large dense cored vesicles formed specialized synapse with a pinealocyte process. Within the perivascular spaces nerve fibers and endings, Schwann cells and pericyte were noted. In rare case pinealocyte process penetrated into the perivascular space through the interuptions of glial border. These results suggest that pinealocyte of the cat has less significance in secretory function and is rather neural type of cell.

자라 송과체의 미세구조

최재권,오창석,설동은,박성식,조영국,Choi, Jae-Kwon,Oh, Chang-Seok,Seol, Dong-Eun,Park, Sung-Sik,Cho, Young-Kook 한국현미경학회 1995 Applied microscopy Vol.25 No.2

Pinealocytes in the lower vertebrate are known to have photoreceptive function. These photoreceptor cells have been characterized morphologically in various species of lower vertebrates. No such ultrastructural studies, however, were reported in fresh water turtle. The purpose of this study is to characterize the pinealocytes and the phylogenetic evoluton of these cells is discussed in terms of functional analogy. I. Light microscopy: The pineal body was divided into incomplete lobules by connective tissue septa containing blood vessels, and parenchymal cells were arranged as irregular cords or follicular pattern. In the lobules, glandular lumina were present and contained often densely stained materials. II. Electron microscopy: The pineal parenchyma had three categories of cells: photoreceptor cells, supportive cells and nerve cells. The photoreceptor cells had darker cytoplasm compared to the supportive cells, and the enlarged apical cytoplasm(inner segment) containing abundant mitochondria and dense cored vescles protruded into the glandular lumen in which lamellar membrane stacks(outer segment), dense membranous materials, and cilia were present. Some of these lamellated membrane stacks appeared to be dege-nerating while others were apparently newly formed. Constricted neck portion of the photoreceptor cells contained longitudinally arranged abundant microtubules. centrioles and cross-striated rootlets. Cell body had well developed Golgi apparatus, abundant mitochondria, dense granules($0.5{\sim}1{\mu}m$), dense cored vesicles($70{\sim}100nm$), and rough endoplasmic reticulum occasionally with dense material within its cisterna. Basal portion of the photoreceptor cells had basal processes often with synaptic ribbons, which terminate in the complicated zone of cellular and neuronal processes. Synatpic ribbons often made contact with the nerve processes and the cell processes of neighboring cells. In some instances, these ribbons were noted free within the basal process and were also present at the basal cell mem-brane facing the basal lamina. Obvious nerve endings with clear and dense cored vesicles were observed among the parenchymal cells. Photoreceptor cells of the snapping turtle pineal body were generally similar in fine structure to those of other lower verterbrates reported previously, and suggested to have both photoreceptive and secretory functions which were modulated by pinealofugal and pinealopedal nerves. The supportive cells were characterized by having large dense granules($0.3{\sim}1{\mu}m$), abundant ribosomes, well developed Golgi apparatus and rough endoplasmic reticulum. These cells were furnished with microvilli on the luminal cell surfaces, and often had centrioles, striated rootlets, abundant filaments especially around the nucleus, and scattered microtubules. Some supportive cells had cell body close to the lumen and extended a long process reaching to basal lamina, which appeared to be a glial cell. Nerve cells within the parenchyma were difficult to identify, but some large cells located basally were suspected to be nerve cells, since they had synaptic ribbon contact with photoreceptor cells.

한국인 태아 조기질의 미세구조에 관한 연구

손형선,최재권,정윤영,배춘상,Sohn, Hyung-Sun,Choi, Jae-Kwon,Chung, Yun-Young,Bae, Choon-Sang 한국현미경학회 1996 Applied microscopy Vol.26 No.1

The differentiation of nail matrix and fine structure of matrix cells were studied with light and electron microscope using specimens from nails of thumb finger in Korean fetuses 14 to 24 weeks old. Fetal nail matrix consisted of two horizontal layers, thicker ventral and thinner dorsal matrices, originating from invagination of epidermis in proximal nail field. Matrix being generally thicker in its distal region than the apex became gradually thickened with increase of the fetal age. Each matrix consisted of single layer of basal cells and multiple layers of squamous cells which are arranged close to and parallel to the central axis of the nail mairix. The process of keratinization of fetal nail matrix was noted to be occured concurrently in the ventral and dorsal matrices along the central axis of matrix toward distal and dorsal direction. Squamous cells became matured with accumulation of tonofilaments, increase of keratohyalin granules, discharge of membrane coating granules, and narrowing of intercellular spaces, thickening of plasma membrane and finally being transformed into horny cells of nail plate. Horny cells of nail plate filled with fibrous elements in the electron dense amorphous substance. These findings of keratinization process of fetal nail matrix appeared to be similar to those of keratinization in epidermis and inner root sheath of the hair. In the nail matrix, however, corresponding region to the keratogenous zone of growing hair follicle was not observed. Vacuolated squamous cells of nail matrix seen on light microscopy was considered to be artefactual product, but squamous cells with condensed small nuclei rarely found adjacent nail plate was considered to be one of the squamous cells with unknown function. Proximal end of nail plate was observed on dorsal surface of nail field distal to the proximal nail fold at 14 and 16 weeks old human embryos. Proximal prolongation of the proximal end of nail plate was occured with advancing fetal age and afterward 21 weeks nail plate invaded into nail matrix. Melanin granule containing cells and Merkel cells were present only on the basal layer of dorsal nail matirx.

[B-18] LPG연료 엔진의 밸브시트 거동환경 최적화에 대한 연구

김승철(Seung Chul Kim),최재권(Jae Kwon Choi),허곤(Kon Hur),안은수(Eun Soo Ahn),이상동(Sang Dong Lee),김청균(Chung Kyun Kim) 한국가스학회 2010 한국가스학회 학술대회논문집 Vol.2010 No.10

이속압연에의해제조된AA1100판재의소성변형비예측

최시훈 ( Shi Hoon Choi ),김형욱 ( Hyoung Wook Kim ),조재형 ( Jae Hyung Cho ),강석봉 ( Seok Bong Kang ),최재권 ( Jae Kwon Choi ) 대한금속재료학회 ( 구 대한금속학회 ) 2010 대한금속·재료학회지 Vol.48 No.7

Conventional rolling (symmetric) and differential speed rolling (DSR) were both applied to AA1050 sheets at various velocity ratios, from 1 to 2 between the top and bottom rolls. An electron backscatter diffraction (EBSD) technique was used to measure texture inhomogeneity through the thickness direction. After the annealing process, the annealing texture of the DSR processed sheets was different from that of conventionally rolled sheets. The velocity ratio between the top and bottom rolls affected the texture inhomogeneity and macroscopic plastic strain ratio of the AA1050 sheets. A prediction for the macroscopic plastic strain ratio of AA1050 sheets was carried out using a visco-plastic self-consistent (VPSC) polycrystal model. The strain ratio directionality that was predicted using the VPSC polycrystal model was in good agreement with experimental results.

수치해석에 의한 고압다이캐스팅용 금형설계 및 주조공정해석

이창호(Chang Ho Lee),최재권(Jae Kwon Choi),남태운(Tae Woon Nam) 한국주조공학회 2000 한국주조공학회지 Vol.20 No.6

N/A Computer simulation for the predictions of casting defects is very important to produce high quality castings with less cost. Complicate shaped Al solenoid housing part was selected to be cold chamber die cast and a numerical simulation technique was applied for the optimization of the chill vent position and gating. A first design led to insufficient central flow. This flow left the last filled areas falling into the inner portion of the part. And last filled area did not fit the chill vent position. So these resulted in a high possibility of air entrapment in the casting and the design was not proper for the part. The design was improved by using a proper gating system, a more chill vent and proper overflow positions. New design provided a homogenous mold filling pattern and the last filled areas that being located at the overflow and chill vent. Casting plan which produce good quality solenoid housing part was established by using the computer simulation.

Intelligent Idle Stop & Go 제어 기법에 따른 연비 효과 연구

황규만(Gyu-man Hwang),권용태(Young-tae Kwon),고성석(Sung-suk Ko),최재권(Jae-kwon Choi) 한국자동차공학회 2014 한국 자동차공학회논문집 Vol.22 No.1

승용차의 중량변화와 공력 개선에 따른 연비 연구

황규만(Gyu-man, Hwang),권용태(Yong-tae, Kwon),고성석(Sung-suk, Ko),최재권(Jae-kwon, Choi) 한국자동차공학회 2013 한국자동차공학회 부문종합 학술대회 Vol.2013 No.5

This study focuses on how to get fuel economy improvement whitout any ECU data change. We should achieve the vehicle Fuel economy and CO2 emission test according to the weight reduce and aerodynamics improvement.

Intelligent Idle Stop & Go제어법에 따른 연비 효과 분석

황규만(Gyu-man Hwang),권용태(Yong-tae, Kwon),고성석(Sung-suk, Ko),최재권(Jae-kwon, Choi) 한국자동차공학회 2013 한국자동차공학회 부문종합 학술대회 Vol.2013 No.5

This study focuses on how to maximize fuel economy improvement of I.S.G. while keeping 12V system. With 12V system the maximum gain of fuel economy with I.S.G. is known to be about 3~5% in FTP-75 mode because engine stop is only conducted in standstill idle. But in this study deceleration engine stop has been tried additionally and the optimum condition for deceleration engine stop was found to maximize fuel economy improvement in practical point of view, the result of which is about 8.8% in FTP-75.