• Title/Summary/Keyword: First wall

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A Case Study of Paraffin Double-walled Microencapsulation Preparation Using Acrylic Polymer and Melamine Polymer for Thermal Energy Storage

  • Nguyen, Hang Vo-Minh;Kim, Chae-Hyun;Kim, Jong-Kuk
    • Journal of the Korean Solar Energy Society
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    • v.39 no.5
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    • pp.65-78
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    • 2019
  • In this study, we investigated the paraffin encapsulation using double-walled encapsulation technique. The first encapsulation used methyl methacrylic acid as the main component in acrylic polymer and the second encapsulation used melamine polymer. Particles size and distribution of the capsules were analyzed using scanning electron microscopy. In the first encapsulation, the stable capsules were obtained at 67% of phase change material ratio to methyl methacrylic acid monomer and the size of the capsule was from 0.2 to $0.3{\mu}m$. In the second encapsulation, the size of the capsules was almost the same with those capsules prepared in the first encapsulation. The particle size of single wall and double wall was about $0.3{\mu}m$. As a result of the encapsulation of paraffin using double-walled encapsulation technique, it was confirmed that the particle size was determined in the process of encapsulating using the acrylic polymer at the first wall material, and the physical and thermal stability of the capsules were imparted using melamine at the secondary wall material.

Cell Wall Micropore Loading of Pulp Fibers (펄프 섬유의 세포벽 미세공극 충전)

  • Lee, Jong-Man;Jo, Byoung-Muk
    • Journal of the Korean Wood Science and Technology
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    • v.20 no.4
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    • pp.57-64
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    • 1992
  • The unique cell wall micropores of pulp fiber can be utilized as loading site in variety of important practical application which could be the basis of new papermaking technologies. One of these includes the manufature of paper containing higher levels of in situ filler precipitated. Hardwood pulp fiber were first impregnated with the solution of sodium carbonate($Na_2CO_3$). The micropores in cell wall of pulp fibers were filled with the liquid salt solution. The second calcium nitrate($Ca(NO_3)_2$) solution formed an insoluble calcium carbonate($CaCO_3$) precipitate within the cell wall micropores by interacting with the first sodium carbonate solution. The effects of chemical concentration and dryness of pulp fibers on the retention of cell wall micropore loaded filler were investigated. The paper properties of cell wall micropore loaded pulp fibers were compared with those of conventionally loaded and lumen loaded pulp fibers. Also the presense of the fillers within the cell wall micropore was observed by SEM. Increasing the chemical concentration to generate the calcium carbonate increased the retention of filler in cell wall micropore loaded pulp fibers. The particle size distribution of precipitated calcium carbonate ranged from $0.1{\mu}m$ to $80{\mu}m$. But, the average particle size of cell wall micropore loaded calcium carbonate was $4{\mu}m$. The paper made from never dried pulp fibers, the cell wall micropores which were filled with calcium carbonate, had better mechanical and optical properties than those of conventionally loaded or lumen loaded pulp fibers.

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Experiment on measures of heat collection for passive solar water wall systems that provide heat storage and natural lighting control (축열과 채광조절을 겸한 자연형 태양열 수벽시스템의 집열방식별 성능실험)

  • Oh, Young-hoon;Choi, Ji-eun;Lee, Chul-sung;Yoon, Jong-ho
    • KIEAE Journal
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    • v.16 no.4
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    • pp.63-69
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    • 2016
  • Purpose: This preliminary study investigated a potential of the water wall systems that provide heat storage and natural lighting control simultaneously. Method: In order for transparency of the water wall to be controlled, the study first proposed two measures: to adjust transparency of the water wall; to control transparency of water wall surface. The performance of two measures then was verified and compared by experiments. In addition, a trade-off between heat collect and heat storage resulting from using additive for adjusting transparency was investigated. Result: The experiment showed that the two measures are similar in performance. The investigation of trade-off relation showed the additive should have the same heat storage as the water to prevent decrease in thermal performance of the water wall. As an economical measure to control transparency of the water wall, this study suggested a measure of secondary heat transfer systems using shading device that first absorbs solar radiation and then transfers heat to the water wall. The experiment show that performance of the proposed measure is similar to controlling transparency of water wall surface. In conclusion, it is expected that the performance of the water wall can be economically maximized by using the proposed mean in terms of heating, cooling and lighting energy saving.

Geometric Characteristic of Wall-thinning Defect Causing Circumferential Crack in Pipe Elbows (원주방향 균열이 발생되는 곡관 감육부의 형상적 특성)

  • Kim, Jin Weon;Lee, Sung Ho
    • Transactions of the Korean Society of Pressure Vessels and Piping
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    • v.7 no.1
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    • pp.27-34
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    • 2011
  • The objective of this study is to classify the geometry of wall-thinning defect that causes a circumferential crack in the pipe elbows subjected to internal pressure. For this objective, first of all a criterion to determine the occurrence of circumferential cracking at wall-thinned area was developed based on finite element simulation for burst tests of pipe elbow specimens that showed axial and circumferential cracking at wall-thinned area. In addition, parametric finite element analysis including various wall-thinning geometries, locations, and pipe geometries was conducted and the wall-thinning geometries that initiate circumferential crack were determined by applying the criterion to the results of parametric analysis. It showed that the circumferential crack occurs at wall-thinning defect, which has a deep, wide, and short geometry. Also, it is indicated that the pipe elbows with larger radius to thickness ratio are more susceptible to circumferential cracking at wall-thinned area.

Structural Performance for Sandwich Insulation of Reinforced-Concrete (현장타설 중단열 RC벽체의 구조적 성능)

  • Park, Jun-Ho;Yu, Jung-Ho
    • Proceedings of the Korean Institute of Building Construction Conference
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    • 2015.05a
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    • pp.19-20
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    • 2015
  • Building exterior wall's energy loss is very high rate comparing to all part of a buildings. And it account for upper 40% of cooling and heating load. So many studies conducted improving insulation performance of building's exterior, appeared about sandwich insulation wall which could be gaining merit of traditional insulation method those are exterior insulation and interior insulation. In this study, we inform structural performance of sandwich insulation wall for RC wall. For this, first, we define each wall's role and design sandwich insulation wall. At last, analyze structural performance of sandwich insulation wall. This study can contribute to apply it safely where side wall which toilet, stair area, etc.

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Experimental study on the behavior of retaining wall according to underground excavation distance (지하굴착 이격거리에 따른 흙막이벽체 거동에 대한 실험적 연구)

  • Park, Jong-Deok;Ahn, Chang-Kyun;Kim, Do-Youp;Lee, Seok-Won
    • Journal of Korean Tunnelling and Underground Space Association
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    • v.18 no.2
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    • pp.155-164
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    • 2016
  • The changes in earth pressure and ground settlement due to the underground excavation nearby the existing retaining wall according to the separation distance between underground excavation and retaining wall, were studied experimentally. A soil tank having 160 cm in length and 120 cm in height, was manufactured to simulate the underground excavation like tunnel by using 5 separated bottom walls. The variation of earth pressure was measured according to the excavation stages by using 10 separated right walls simulating the retaining wall. The results showed that the earth pressure was changed by the lowering of first bottom wall(B1), however the earth pressure was not changed significantly by the lowering of third bottom wall(B3) since B3 had sufficient separation distance from retaining wall. Lowering of first bottom wall(B1) induced the decrease of earth pressure in lower part of retaining wall, on the contrary, lowering of first bottom wall(B1) induced the increase of earth pressure in middle part of retaining wall proving the arching effect.

Rotordynamic Analysis for Stepped-Labyrinth Gas Seals Using Moodys Friction-Factor Model

  • Ha, Tae-Woong
    • Journal of Mechanical Science and Technology
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    • v.15 no.9
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    • pp.1217-1225
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    • 2001
  • The governing equations are derived for the analysis of a stepped labyrinth gas seal generally used in high performance compressors, gas turbines, and steam turbines. The bulk-flow is assumed for a single cavity control volume set up in a stepped labyrinth cavity and the flow is assumed to be completely turbulent in the circumferential direction. The Moodys wall-friction-factor model is used for the calculation of wall shear stresses in the single cavity control volume. For the reaction force developed by the stepped labyrinth gas seal, linearized zeroth-order and first-order perturbation equations are developed for small motion about a centered position. Integration of the resultant first-order pressure distribution along and around the seal defines the rotordynamic coefficients of the stepped labyrinth gas seal. The resulting leakage and rotordynamic characteristics of the stepped labyrinth gas seal are presented and compared with Scharrers theoretical analysis using Blasius wall-friction-factor model. The present analysis shows a good qualitative agreement of leakage characteristics with Scharrers analysis, but underpredicts by about 20%. For the rotordynamic coefficients, the present analysis generally yields smaller predictied values compared with Scharrers analysis.

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A Study On The Propagation Failure Modes of Ion Implanted Magnetic Bubble Computer Memory Devices (이온주입식 자기버블 전산기 기억소자에서의 자기버블 전파실패에 관한 연구)

  • Jo, Soon-Chul
    • Proceedings of the KIEE Conference
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    • 1988.07a
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    • pp.339-342
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    • 1988
  • Typical magnetic bubble propagation failure modes of ion implanted magnetic bubble computer memory devices were observed and their failure mechanisms were analize. The skidding failure mode is due to the pushing of a strong repulsive charged wall. If this pushing is stronger than the edge affinity of the bubble in the cusp, the bubble moves out of the cusp when it is supposed to stay there. The stripeout failure modes across the adjacent track or along the track can be explained by considering the relative strength of the charged wall and the edge affinity encountered by both ends of the stripe. The skipping of the first cusp of a track is believed to be due to the whipping motion of the charged wall. The bubble moves directly to the second cusp via the long charged wall pointing to the second cusp skipping the first cusp.

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A Study on the Architectural Design Plans Using BIPV (BIPV를 활용한 건축물 디자인 계획에 관한 연구)

  • Juen, Guen-Sik;Ryu, Soo-Hoon
    • Journal of The Korean Digital Architecture Interior Association
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    • v.12 no.3
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    • pp.5-13
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    • 2012
  • In this study, features and design effects of PV(Photovoltaic) modules were classified to help the installation of BIPV(Building Integrated Photovoltaic) In addition, through domestic and international trends and cases survey, installation method was organized and applicable range of efficiency and design from First-generation solar cells to the third-generation solar cell was classified. Frist, Crystalline Solar cell module of first-generation is appropriate for the wall type, roof, louver, shading and etc. It has superiority of technology and price stability and can be achieved by a variety of aesthetic effects. Second, Dye-Sensitized Solar Cell of Thin Film solar cell can express a variety of colors, adjust light transmittance and maximize the aesthetic splendor. It is appropriate for the wall type, window type, curtain wall type and etc. Also, see-through type solar cell can provide comforts cause of free flow of light. And it is advantageous from economic due to adjust the indoor temperature. It is appropriate for the atrium type, curtain wall type, window type and etc.

A Study on the Usage of Hwabangbyeok wall in Traditional Architecture in Joeson Dynasty (조선시대 전통건축에서의 화방벽(火防壁) 사용에 대한 연구)

  • Jo, Sang-Sun
    • Journal of architectural history
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    • v.29 no.3
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    • pp.7-14
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    • 2020
  • It can be meaningful that this study attempted to analyze the use cases and forms based on the literature on the painting walls of the J oseon Dynasty, and attempted basic research to prevent disaster damage using traditional elements. This study summarizes the use of the Hwabangbyeok wall of J oseon Dynasty as follows. First, Hwabangbyeok wall was used from the early J oseon Dynasty and was adopted by palaces and other major state facilities to cope with fire and theft. Second, the Hwabangbyeok Wall was also referred to as the wall below the lower part of the wall, and was constructed with the purpose of preventing disasters from outside. Third, in an analysis of the Daeseongjeon shrine of Hyanggyo, many construction cases were identified mainly in the Gyeonggi area, which is assumed to be based on production and construction conditions along with local climatic factors. Fourth, it can be said that the Hwabangbyeok wall was basically adopted to prevent comprehensive disaster risk reduction in case of external intrusion and fire.