• 보존과학연구
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• 통권29호
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• pp.65-90
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• 2008

This study examines the status and the physical features of Paraloid B-72 layers with examination of microstructure and analysis of organic matters. Paraloid B-72 layers were coated on samples from the colour layer of outer wall painting in Mireuk hall in Geumsan temple. On the basis of the previous examination result, it has made the samples which are similar to outer wall in Mireuk hall in Geumsan temple. The samples can be divided into two, one; 5% Paraloid B-72 coating and another is without coating. Then samples have been experimented under the compulsive environments of infrared radiation and immersion, thereafter compared the results of the damages and physical features between two samples. As a result of the comparison, the sample with Paraloid B-72 had more serious cracks, exfoliations and peeling layers than that of without Paraloid B-72. Otherwise, in the examination of ultraviolet radiation, the sample with Paraloid B-72 coating showed weaker physical properties, less density in structure of colour layer and less hardness in surface of colour layer than the sample without coating. The percentage of moisture content after the ultraviolet radiation was higher in the sample without Paraloid B-72 than the sample with Paraloid B-72 coating. Observing the conditions before the ultraviolet radiation, the sample with Paraloid B-72 coating demonstrated lower rate in moisture evaporation rate than the sample without Paraloid B-72. As a consequence, in examination of this samples, the change of physical features are increased in the sample with Paraloid B-72 coating than that without Paraloid B-72 when compulsive environment of heat, moisture and ultraviolet rays for a short term are imposed.

• 한국수산과학회지
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• 제31권3호
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• pp.330-342
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• 1998

영산강 하구역의 저서동물 군집구조 연구 일환으로 이 일대 해역의 저서환경을 조사하였다. 조사해역에 40개 정점을 설정하고 1995년 4월부터 1996년 2월까지 계절별로 표층 및 저층수괴의 수온, 염분 및 용존산소. 그리고 표층퇴적물의 입도분석과 함께 강열감량. COD 및 POC를 측정하였다. 수온은 표층의 경우 $4.1\~29.8^{\circ}C$, 저층의 경우 $4.0\~27.0^{\circ}C$범위였다. 염분의 경우 표층은 $15.1\~33.6\%_{\circ}$, 저층은 $21.5\~33.2\%_{\circ}$범위였다. 표층 수온은 여름철에는 내만역이 외측에 비해 높은 양상이었으며, 가을부터 봄까지는 내만역과 큰 차이를 나타내지 않았다. 저층수온은 여름철에 내만역에 형성된 성층으로 인해 외해역에 비해 상대적으로 낮은 양상이었다. 표층 및 저층염분은 담수가 간헐적으로 유입되는 내만역이 외해역에 비해 전 계절에 걸쳐 통해 낮은 값을 나타내었다. 용존산소는 표층의 경우 $5.1\~11.2mg/\ell$ 범위였으며 저층의 경우 $0.79\~10.2mg/\ell$였다. 특히 여름철에는 하구둑에서 목포항에 이르는 내만역의 광범위한 해역에 $2.0mg/\ell$ 이하의 저층빈 산소수괴가 형성되었다. 퇴적물의 평균입도는 $9.12{\pm}0.45\phi$로서 하구둑에서 외해역으로 나갈수록 입도가 조립해지는 양상이었다. 퇴적상은 내만역에는 실트성 점토질, 외측역에는 점토성 실트질의 퇴적상이었다. 퇴적물의 COD는 $6.15\~15.49mg\;O_2/g$범위로서 평균 $10.59{\pm}12.64mgO_2/g$였으며, 강열감량은 $3.35\~15.45\%$범위로서 평균 $6.96{\pm}1.91\%$였다. POC는 $0.61\~1.39\%$범위로서 평균 $1.07{\pm}0.16\%$였다. 이들 퇴적물 환경요소들의 공간분포양상은 내만역에서 높고 외해역으로 갈수록 감소하는 양상을 나타내었다. 저층수괴의 수온, 용존산소량, 퇴적물의 평균 입도, 점토 함량, COD 등 5가지 환경 요인을 사용하여 주성분분석을 실시한 결과 영산강 하구역은 저층수괴의 용존산소량과 퇴적물의 점토 함량에 따라 3개의 정점군으로 구분되었다. 영산강 하구둑에서 목포항 주변까지를 포함하는 내만역에 위치한 정점군은 표층염분과 저층수온이 낮으며, 입도는 상대적으로 세립하며 유기물 함량이 높고 여름철 빈산소 수괴가 형성되는 정점군이다. 고하도와 화원반도로 둘러싸이고 목포구 수로를 통해 외해역과 면해 있는 정점군에서의 퇴적물 입도는 상대적으로 조립하며 유기물 함량은 낮은 양상이었다. 또한 여름철에도 산소결핍 현상은 발생하지 않았으며, 저층수온과 저층염 분도 다른 정점군에 비해 상대적으로 높은 양상이었다. 한편 목포항 주변에서부터 외해역과의 중간에 위치한 정점군에서의 제환경 요소들은 두 정점군의 중간값을 나타내고 있다. 결국, 각 정점군의 점토 함량의 차이 및 세립한 입도와 높은 유기물 함량. 그리고 빈산소 수괴의 출현은 영산강 하구역에서 저서동물의 공간분포 양상에 영향을 미칠 수 있는 특징적인 환경요인이라고 판단된다.

• Applied Microscopy
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• 제16권2호
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• pp.61-74
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• 1986

The anatomy of the renal papilla and pelvis of the bat(Pipistrellus abramus abramus Temminck) and their ultrastructure of the epithelium has been studied by means of light, scanning and transmission electron microscopy. The bats were captured at Ondal cave located in Yangchun-Myun, Tanyang-Kun, Chungchongpuk-Do, Korea in the active(July) and hibernating(January) phases. A conical renal papilla with several papillary foramina at the apex was curved toward the ureter. At the margin of the funnel-shaped renal pelvis, the fornix extended deeply into the kidney parenchyme was formed between the outer zone of the medulla and the cortex. The epithelium of the papilla covered the inner zone of the medulla. The epithelium of the fornix medially overlayed the outer zone of the medulla, and laterally the cortex. The surface epithelium of the papilla was simple columnar in shape with the scanty organelles and the short microvilli on their luminal surface. The fornix was Jined with $1{\sim}2$ cell layered squamous epithelium. On the medial surface of the fornix, two types of the superficial epithelial cells were identified; one had numerous short microvilli and the other had the microplicae and plaques on their luminal surface. The lateral surface of the fornix lined with the epithelial cells showed microridges and plaques on the luminal surface. The epithelial cells on the medial and lateral surfaces of the fornix were similar to their internal ultrastructures. The pelvic epithelium was a typical transitional type, which was composed of a layer of basal cells, one or two layers of intermediate cells, and a layer of superficial(facet) cells. The fusiform vesicles were observed in the cytoplasm of the intermediate and facet cells. There were no noticeable morphological changes in the epithelium of the papilla, fornix and pelvis except the medial epithelium of the fornix in the hibernating cycle. The microvillar cells were more numerous in the hibernating phase than in the active phase. The morphology, of the renal papilla and fornix of bats, indicates that a functional relationship may exist between the pelvic urine and the renal parenchyme.

• 한국표면공학회:학술대회논문집
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• 한국표면공학회 2016년도 추계학술대회 논문집
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• pp.173.2-173.2
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• 2016

A two-step oxidation method was applied on Al6061 to debate the growth mechanism of plasma electrolytic oxidation (PEO) coating. The specimens were first oxidized in the primary electrolyte solution {$Na_3PO_4$ (8g/l), NaOH (2g/l), consequently, the specimens were transferred into a different electrolyte {$K_2ZrF_6$ (8g/l), NaOH (2g/l), $Na_2SiF_6$ (0.5g/l)} for further oxidation. The processes was conducted for various processing times. It was found the second step electrolyte component were reached to inner layers, in contrast to the primary step components which were thrustle to the outer layer. The presence of the secondary component in the inner layers were significantly varied with processing time which suggest the change in growth properties with processing time. further more the inside growth of the secondary component confirmed the increasing trend in the downward growth of the coating layer. The corrosion and hardness properties of the coatings were found highly improved with change in growth features with increasing the processing time.

• 대한기계학회논문집A
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• 제24권8호
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• pp.1958-1967
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• 2000

Rapid Prototyping( RP ) has been increasingly applied in the process of design and development of new products. RP can shrink the time and expense required to bring a new product from initial concept to production. However, the necessity of using RP for short-run manufacturing is continuously driving a development of a cost-effective technique that will produce completely-finished quality parts in a very short time. To meet these demands, the improvements in production speed, accuracy materials, and cost are crucial. Thus, a new hybrid-RP system performing both deposition and machining in a station is proposed in this paper. It incorporates both material deposition in layers and material removal from the outer surface of the layer to produce the required surface finish. The new hybrid-RP system can dramatically reduce the total build time and fabricate largo-sized and freeform objects because it uses very thick layers, i.e.

• 설비공학논문집
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• 제24권3호
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• pp.281-287
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• 2012

The internal oxide scale of twelve superheater and reheater tubes were tested which were serviced for 30,000~120,000 hours in thermal power plants. The oxide scale was formed in three layers. The Cr-rich area was observed beneath the original metal surface. The hematite ($Fe_2O_3$) phase was formed on the outer surface. The intermediate layer was magnetite ($Fe_3O_4$). The thickness of Cr-rich layer was about half of the total scale. All layers grew during the operation hour of the plant. The thickness of thickest scale was 0.2mm in superheater tubes. This can increase the tube metal temperature about $7^{\circ}C$ more than initial state. $7^{\circ}C$ tube metal temperature can reduce tube life about 30%, but the boiler tube's design margin is big enough therefore it has been analyzed that it would not effect on the life span.

• Structural Engineering and Mechanics
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• 제34권4호
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• pp.449-474
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• 2010

A smart hollow cylinder consisting of a host functionally graded elastic core layer and two surface homogeneous piezoelectric layers is presented in this paper. The bonding between the layers can be perfect or imperfect, depending on the parameters taken in the general linear spring-layer interface model. The effect of such weak interfaces on free vibration and steady-state response is then investigated. Piezoelectric layers at inner and outer surfaces are polarized axially or radially and act as a sensor and an actuator respectively. For a simply supported condition, the state equations with non-constant coefficients are obtained directly from the formulations of elasticity/piezoelasticity. An approximate laminated model is then introduced for the sake of solving the state equations conveniently. It is further assumed that the hollow cylinder is embedded in an elastic medium and is simultaneously filled with compressible fluid. The interaction between the structure and its surrounding media is taken into account. Numerical examples are finally given with discussions on the effect of some related parameters.

• 한국표면공학회지
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• 제37권6호
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• pp.360-365
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• 2004

Ti$_3$SiC$_2$ material was synthesized via the powder metallurgical route, and oxidation tested between 900 and $1200^{\circ}C$ in air for up to 100 hr. The oxidation of $Ti_3$$SiC_2$ material resulted in the formation of $TiO_2$and $SiO_2$, accompanying the evolution of CO or $CO_2$ gases from the initial stage of oxidation. The oxidation resistance of $Ti_3$$SiC_2$ mainly owes the protectiveness of highly stoichiometric $SiO_2$. During the initial stage of oxidation, the dominant reaction was the inward transport of oxygen into the matrix. As the oxidation progressed, an outer $TiO_2$ layer and an inner ( $TiO_2$ + $SiO_2$) mixed layer formed. Between these layers and inside the oxide scale, numerous fine voids formed. Numerous, fine oxide grains formed at $900^{\circ}C$ developed into the outer coarse $TiO_2$ grains and an inner fine ($TiO_2$ + $SiO_2$) mixed grains at the higher temperatures. The oxidation resistance of$ Ti_3$SiC$_2$ progressively deteriorated as the oxidation temperature increased, forming thick scales above $1000^{\circ}C$. The outer coarse $TiO_2$ grains formed above $1100^{\circ}C$ grew rapidly mainly along (211).

• Parasites, Hosts and Diseases
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• 제21권1호
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• pp.75-82
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• 1983

An electron microscopic study was performed to know the basic tegumental structure of Cysticercus cellulosae. The scolex and bladder portions of cysticerci (human and porcine strains) were prepared for transmission and scanning electron microscopy by conventional procedures. In general, the tegument of C. cellulosae showed the basic ultrastructure of cestode tegument on electron micrographs. The teguments of both scolex and bladder portions consisted of such components, i.e., an outer vesicular layer with numerous microtriches and inner filroug layer. Below the fibrous layer, there were layers of muscle bundles and tegumental cells. The microtriches which covered the surface of cysticercus revealed two distinctly different shapes. The characteristic bladder-like, elongated pyramid shaped "tetrahedrial form" was observed on the surface of the scolex portion, whereas the elongated cylindrical "filamentous form" was distributed on the stirface of bladder portion. In spite of the difference of isolated host and location, the cysticerci showed tole same result. But dimensional variations of the tegument according to topography of the worm were observed. The possibility of application in making differential diagnosis from other larval cestodes and possible functions of this larval tegument were discussed.

• 한국표면공학회지
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• 제29권4호
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• pp.261-267
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• 1996

The characteristics and adhesion strength of TiN layer deposited by D. C. magnetron sputtering were investigated. Three types of TiN layers were deposited on STS304 stainless steel. Scratch tests were performed to determine the effect of deposition temperature, the thickness of coated TiN layer and the titanium inter-layer on the adhesion strength. TiN multilayer with titanium inter-layer showed the highest critical load in the deposition temperature range of $25^{\circ}C$ to $300^{\circ}C$. Adhesion strength of TiN multilayer with titanium inter-layer was raised from 15N to 20N by raising deposition temperature from $25^{\circ}C$ to $400^{\circ}C$. Adhesion strength was raised from 18N to 38N by increasing the thickness of outer layer of TiN multilayer from 2.1 $\mu\textrm{m}$ to 9.5 $\mu\textrm{m}$.