• 콘크리트학회논문집
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• 제26권1호
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• pp.71-78
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• 2014

사용후핵연료의 중간저장시설인 콘크리트 캐스크(cask)는 해안부근에 입지할 가능성이 크기 때문에 염해에 대한 문제가 크게 우려된다. 그리고 염해에 의한 철근의 부식 및 균열발생은 철근콘크리트구조물의 방사선 차폐기능뿐 아니라 구조성능 저하의 주요 원인이기 때문에 염해에 대한 평가는 매우 중요한 사항이다. 특히 염해환경과 함께 콘크리트 캐스크 내부에서는 사용후핵연료의 발열에 의해 $60^{\circ}C$정도의 고온 환경이 예상되기 때문에 고온에서의 염해에 대한 검토가 요구되지만, 기존 콘크리트 구조물의 염해평가에서는 온도에 대한 영향이 전혀 고려되어 있지 않아 고온에서 염해에 노출된 철근콘크리트구조물들의 내구설계 및 수명예측을 위해 참고할 만한 자료가 거의 없다. 이 연구에서는 다양한 온도환경에서의 염수(NaCl)침지시험을 통해 콘크리트의 염화물이온 확산계수를 측정하고 염화물이온 확산계수와 온도의 관계를 규명하고자 하였다. 실험 결과, 콘크리트의 염화물이온 확산계수는 온도의 증가에 따라 현저히 증대하여 고온환경에서의 염해 발생가능성이 매우 큰 것으로 조사되었다. 또한 크리트의 염화물이온 확산계수는 물시멘트(W/C)비가 낮아질수록 감소하였고, 이 경향은 온도가 증가(고온환경)하여도 동일하게 나타났다. 염화물이온 확산계수의 온도의존성은 아레니우스식(Arrhenius equation)으로 나타내어졌고 회귀분석 결과, 확산계수의 대수 값은 절대온도의 역수와 선형관계를 나타내었다. 또한 온도의존성을 나타내는 활성화에너지(activation energy)는 물시멘트(W/C)비가 낮을수록 높게 나타났다.

• Journal of the Korean Wood Science and Technology
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• 제17권3호
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• pp.67-81
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• 1989

This experiment was carried out to know the mothod of changing the step of moisture content schedule with time in conventional kiln drying. For the purpose of this object. we made drying model by applying the moisture diffusion model by J.FSiau(1984) to average moisture content equation by J.Crank(1956) derived it from Fick's second law. And to verify this method of drying model. 2.5cm-thick boards and 5.0cm-thick dimension lumbers of Pinus densiflora were kiln-dried with the schedule of T11-C3 and T10-C4, respectively. And then the drying rates were investigated and compared with those calculated from drying model. The results obtained were as follows 1. Average drying rate and total drying time of board to dry to 6.5% moisture content were 0.64%/hr and 109hr., and those of dimension lumber to dry to 8.3% moisture content were 0.4%/hr. and 162hr., respectively. 2. The moisture content of shell and core decreased by equalizing treatment and increased by conditioning treatment both on board and dimension lumber. But the moisture gradient was lower after conditioning than after equalizing. 3. As the drying was proceeded, the transverse bound water diffusion coefficient all but linearly decreased, the water vapor diffusion coefficient abruptly curvilinearly increased, while the transverse diffusion coefficient curvilinearly decreased both on board and dimension lumber. But each of diffusion coefficients on board was larger than that on dimension lumber. 4. Compared to experimential drying rate of board. theoretical drying rate was larger at 30.0%-21.8% moisture content range and was similiar at 21.8%-5.4% moisture content. And in case of dimension lumber, the drying rate was similiar at 30.0%-16.1% moisture content range but theoretical drying rate was much lower at 16.1%-8.3% moisture content range. 5. The possibility of adapting this drying model to changing the moisture content schedule step with time was in the range of 21.8%-5.4% moisture content on board. And in the case of dimension lumber that was in the range of 30.0%-16.1% moisture content.

• 대한치과기공학회지
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• 제35권2호
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• pp.137-142
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• 2013

Purpose: This study was to observe the surface and interfacial characteristic of Zirconia by surface treatment. And it was observed the roughness and contact angle according to processing, and the interfacial properties by surface treatment on zirconia. Methods: The oxide formation and ion diffusion between core and veneer ceramic were determined by the X-ray Dot Mapping of EPMA(Electron probe micro analyzer). The roughness was measured by 3D Digital microscope and the contact angle according to processing of zirconia was observed using distilled water on the surface. Results: The surface roughness of the specimens Z04, Z12, Z15 was measured $0.67({\pm}0.03){\mu}m$, $0.50({\pm}0.12){\mu}m$, $0.35({\pm}0.09){\mu}m$, respectively. As results of contact angle test, Z04, Z12, Z15 of specimen group without binder treatment was measured $46.79({\pm}3.17)^{\circ}$, $57.47({\pm}4.83)^{\circ}$, $56.19({\pm}2.66)^{\circ}$, respectively. but, L04, L12, L15 of specimen group without binder treatment was measured $63.84({\pm}2.20)^{\circ}$, $66.08({\pm}0.16)^{\circ}$, $65.10({\pm}1.01)^{\circ}$, respectively. Average contact angle of L15 was measured $65.10({\pm}1.01)^{\circ}$. In X-ray Dot Mapping results, thickness of binder including Al element was measured that each of L04, L12, L15 were $20{\mu}m$, $15{\mu}m$, $10{\mu}m$. Conclusion: The more rough surface increases the wettability, but the sintered exclusive binder decreases the wettability.

• 열처리공학회지
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• 제32권2호
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• pp.79-85
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• 2019

To investigate the influence of heat treatment on the growth intermetallic compounds (IMCs) at the joint interface of friction-welded Cu-Al, several heat treatments are performed at three different temperature with different times. The experiments reveal three different IMCs layers which are significantly influenced by atomic diffusion of Cu and Al with heat treatment conditions. Since the formation of these IMCs layers can affect mechanical properties of friction-welded Cu-Al interfaces, the relationship between the microstructure of IMCs layers and the tensile strength is analyzed according to heat treatment temperature and times.

• 한국결정성장학회지
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• 제9권3호
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• pp.327-333
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• 1999

Ion implantation, photo-lithography, Ar ion milling, hot press를 이용한 micro-fabrication 방법으로 고순도 단결정 알루미나 표면에 Ca를 제한된 양으로 첨가하고, 내부에 여러 가지 형태의 기공을 갖는 bi-crystal을 만들었다. 이 bi-crystal 고순도 알루미나에 미치는 Ca의 영향을 평가하기 위하여 내부 기공의 형태 변화와 결정의 성장을 열처리에 따라 광학현미경으로 관찰하였다. 열처리에 따라 inner crack-like pore의 내부표면에 dot와 육각형의 형태를 갖는 결정 입자가 생성되는 것을 관찰할 수 있었다. $1,500^{\circ}C$로 열처리한 경우에 CaO . $6Al_2O_3$로 생각되는 bar 형태의 결정이 표면에 석출되는 것이 관찰되었으며, 이 결정이 $1,600^{\circ}C$에서 열처리하면 사라지는 것으로 보아 이 온도 부근에서 알루미나에 대한 Ca의 solubility limit 또는 diffusion rate가 변화하는 것으로 생각된다.

• 산업기술연구
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• 제20권A호
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• pp.73-82
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• 2000

This study was implemented to find an optimal model for wastewater treatment processes using PHOENICS(Parabolic, hyperbolic or Elliptic Numerical Integration Code Series) and ASM(Activated Sludge Model). PHOENICS is a general software based upon the laws of physics and chemistry which govern the motion of fluids, the stresses and strains in solids, heat flow, diffusion, and chemical reaction. The wastewater flow and removal efficiency of particle in two phase system of a grit chamber in wastewater treatment plant were analyzed to inquire the predictive aspect of the operational model. ASM was developed for a biokinetic model based upon material balance in complex activated sludge systems, which can demonstrate dynamic and spatial behavior of biological treatment system. This model was applied to aeration tank and settling chamber in Choonchun city, and the modeling result shows dynamic transport in aeration tank. PHOENCS and ASM could be contributed for the optimal operation of wastewater treatment plant.

• 열처리공학회지
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• 제14권2호
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• pp.81-88
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• 2001

The effects of post-oxidation and sulfnitriding treatments on the phase transformation in the nitrided case of tool steels have been studied. Dense and compact $Fe_3O_4$ layer was formed at the outer surface of nitride compound layer by post-oxidation treatment and multi layer of iron sulfide(FeS) was formed in the compound layer by sulfnitriding treatment. The surface hardness decreased because of formation of the soft oxide or sulfide at the nitride surface. Diffusion layer of nitride case was not affected by post-oxidation treatment or sulfnitriding treatment of nitrided alloy tool steels.

• 한국초전도저온공학회:학술대회논문집
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• 한국초전도저온공학회 1999년도 제1회 학술대회논문집(KIASC 1st conference 99)
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• pp.14-17
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• 1999

Four designed $Nb_{3}$Sn superconductors have been fabricated in order to investigate the effect of pre-heat treatment for internal tin process. 3 types of sub-elements and 2 types of Sn reservers were fabricated. Diffusion of Sn is better in the strand divided Sn equally than in the strand had one large Sn reserver during pre heat-treatment.

• 기술사
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• 제15권2호
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• pp.43-44
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• 1982

What I would like to expect about this mater is that Korea would develop unique techniques of the waste water which are most suitable to social and other relevant conditions of that country, not entirely following models of sewerage construction of U.S.A. or European countries or Japan. Some cements will be made in the followings: (1) The investigation for the diffusion of seperated simple public sewerag, not the large scale sewerage treatment plant. (2) The plan for non-mixed treatment of lining waste water and industrial waste water. (3) Suggestion for "a man of ability" at the university education to cultivate a technologist of facilities and the elemental watchman at the sewerage maintenance.

• 한국연초학회지
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• 제8권2호
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• pp.43-49
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• 1986

Field experiment was conducted to investigate the effect of vinyl mulch on phosphate availability of soil and fertilizer in 1982. Growth of tobacco was more vigorous at each level of phosphate treatment in vinyl mulched than in bare soil. There was significant culture x Phosphorus treatment interaction for the yields of cured tobacco leaves. These results indicated that vinyl mulch was effective to improve phosphate availability of soil and fertilizer. Increase in soil temperature and maintenance of bulk density suitable for Phosphorus diffusion by vinyl mulch were likely to Play major roles on Phosphate availability, but other unknown factors appeared to be involved.