스티븐 홀의 복합 프로젝트에 나타난 도시 다공성(多孔性:porosity) 접근 방식과 계획적 특성

김수미(Kim, Soomi) 대한건축학회 2015 대한건축학회논문집 Vol.31 No.5

In the recent complex projects of Steven Holl, it tends to appear that phenomenological approaches in Holl’s architecture are extended to the urban scale and urban porosity has been represented. This could be led by long period"s experiments about porosity and architectural application of Menger"s Sponge theory. Along with this, multi complex projects in Steven Holl"s architecture were successfully accomplished representing various characteristics of urban porosity. Therefore, this study aims to find out Steven Holl’s approaches and planning characteristics based on urban porosity and with this, to review architectural and urban values. The results are as follows. Firstly, in the formal approaches, they showed that typological analysis referenced from the city with variously presenting urban porosity. Secondly, in the connecting way among the masses, connecting bridges with porosity were represented. Thirdly, phenomenological spaces were converged to the realm of urban environmental publicity connecting with the urban environmental issues.

불포화 다공질매질의 물성치 측정을 위한 실험적 연구

김만일 ( Man Il Kim ) 대한지질공학회 2004 지질공학 Vol.14 No.2

포화 및 불포화 상태로 이루어진 지반 내에서 지하수의 함양 및 오염물질의 침투 이동은 지반을 구성하고 있는 다공질 매질의 공극률과 유효공극률에 매우 큰 영향을 받는다. 본 연구는 불포화 매질에 대한 유효공극률을 측정하기 위해서 Frequency domain reflectometry(FDR) system 및 측정센서를 개발하여 실내실험을 수행하였다. 또한 측정된 유전율상수의 관계로부터 유효공극률을 산정할 수 있는 유전율 믹싱모델(dielectric mixing model)을 제안하였다. 실험결과에서 불포화 흙 시료인 표준사(standard sand)와 강모래(river sand)의 유효공극률의 범위는 공극률과 비교해 약 65∼85% 내외에서 측정되었다. 특히, 측정된 유효공극률과 공극률의 관계에서 공극률이 증가할수록 유효공극률은 다소 감소하는 경향을 보이는 것으로 측정되었다. 이는 흙 입자사이의 공극 내에 존재하는 미량의 공기에 의한 것으로써 불포화 상태의 흙 칼럼이 충분히 포화 상태에 도달하지 못하였기 때문이다. The permeation movements of groundwater recharge and contaminate materials receive a great effect due to porosity and effective porosity of porous media which is composing underground consisted of saturation and unsaturated states. This study developed Frequency Domain Reflectometry(FDR) system and measurement sensor, and then carried out the laboratory experiments to measure effective porosity for unsaturated porous media. Also, I suggested dielectric mixing models(DMMs) which can calculate the effective porosity from relation of measured dielectric constants. In the experimental results the extent range of effective porosity of standard sand and river sand which are unsaturated soil sample were measured in about 65∼85 % for porosity. In relation of effective porosity and porosity, especially, effective porosity confirmed that displays decreasing a little tendency as porosity increases. This is because unsaturated soil did not reach in saturation enough by air of very small amount that exist in pore between soil particles.

열충격 시험에 의한 암석의 물성변화

김재환,이명성,이재만,이미혜,박성미,Kim, Jae-Hwan,Lee, Myeong-Seong,Lee, Jae-Man,Lee, Mi-Hye,Park, Sung-Mi 국립문화재연구소 2010 保存科學硏究 Vol.31 No.-

This study were performed thermal shock test for four kind of different rocks (Iksan granite, Namsan granite, Jeongseon marble, Yeongyang sandstone), and according to heating temperature($400^{\circ}C$, $600^{\circ}C$) on samples were investigated physical properties such as specify gravity, porosity, p-wave velocity. As a result, the tendency was appeared that porosity increased, and specific gravity and p-wave velocity decreased at a more higher temperature. But, the situation of change appeared characteristic according to temperature and rock types. In the case of Yeongyang sandstone, it appeared in especially porosity increasing at $400^{\circ}C$. The specific gravity was little change in the all the rock at $400^{\circ}C$ but the decreased at $600^{\circ}C$. Therefore the specific gravity in the temperature range is due to the relatively small impact on the change is expected. Porosity of the granite at $400^{\circ}C$ changes little. but marble in the rate of change is large. Conversely, the sandstone porosity decreased. At $600^{\circ}C$ increased porosity in all of rocks. particularly sandstone the smallest increase in porosity. Experiments showed that p-wave velocity measured through dry rocks was sensitive to quantify the thermal damage. The p-wave velocity of all rocks decreased with increasing temperature. In the relation between porosity and p-wave velocity, p-wave velocity decreased with increasing porosity. On the other hand, in case of Yeongyang sandstone p-wave velocity decreased with decreasing porosity. thus, development of microcracks more affects p-wave velocity than porosity. In this study, damage intensity was well explained with porosity and p-wave velocity values depending on temperature increase.

암석시험편 유효공극률 측정의 반복성과 재현성

이태종 ( Tae Jong Lee ),이상규 ( Sang Kyu Lee ) 한국지구물리·물리탐사학회 2012 지구물리와 물리탐사 Vol.15 No.4

Repeatability and reproducibility in solid weight and effective porosity measurements have been discussed using 8 core samples with different diameters, lengths, rock types, and effective porosities. Further, the effect of temperature on the effective porosity measurement has been discussed as well. Effective porosity of each sample has been measured 7 times with vacuum saturation method with vacuum pressure of 1 torr and vacuum time of 80 minutes. Firstly, effective porosity of each sample is measured one by one, so that it can provide a reference value. Then for reproducibility check, effective porosity measurements with vacuum saturation of 2, 4, and 8 samples simultaneously have been performed. And finally, repeated measurements for 3 times for each sample are made for repeatability check. Average deviation from the reference set in solid weight showed 0.00 g/cm3, which means perfect repeatability and reproducibility. For effective porosity, average deviations are less than 0.07% and 0.05% in repeatability and reproducibility test sets, respectively, which are in good agreement too. Most of porosities measured in reproducibility test lies within the deviation range in repeatability test sets. Thus, simultaneous vacuum saturation of several samples has little impact on the effective porosity measurement when high vacuum pressure of 1 torr is used. Air temperature can cause errors on submerged weight read and even effective porosity, because it is closely related to the temperature, density, and buoyancy of water. Consequently, for accurate measurement of effective porosity in a laboratory, efforts for maintaining air or water temperature constant during the experiment, or a temperature correction from other information are needed.

국내에서 딸기 수경 재배용 상토로 유통되는 유·무기 물질의 물리적 특성

김윤섭,박인숙,박명선,최종명 한국원예학회 2020 원예과학기술지 Vol.38 No.4

This study was carried out to investigate the aging effects of coir dust (CD) and different origins of peat mosses (PM) on root substrate physical properties. The blending effects of CD or PM with various ratios of vermiculite (VL) or perlite (PL) on the changes in physical properties were also investigated. The physical properties of aged coir dust (ACD) compared to fresh coir dust (FCD) showed no significant differences in total porosity. But, container capacity increased from 59.6% to 71.1%, and air-filled porosity decreased from 30.1% to 18.9%. The total porosity of imported PM was, 83.8% in Estonia, 82.6% in Canada, 82.5% in Latvia, and 81.8% in Lithuania. The container capacity of Lithuanian PM was the highest with 75% followed by 73.1% in Canada, 71.8% in Latvia, 71.2% in Estonia, but the air-filled porosities were 12.5% ​​in Estonia, 10.7% in Latvia, 9.50% in Canada, and 6.90% in Lithuania. When the mixing rate of vermiculite to ACD or FCD were elevated, the total porosity was reduced and the elevation in ACD resulted in the quadratic decrease of air-filled porosity (R2 = 0.6127, p ≤ 0.01). By increasing the mixing ratio of perlite to ACD or FCD resulted in the decrease of total porosity. Similarly, by increasing the quantity in mixing ratio of pearlite to ACD, decreased the container capacity with the quadratic tendency (R2 = 0.5687, p ≤ 0.01). The elevation of mixing ratios of PL or VL influenced differently on total porosity, air-filled porosity, and container capacity in each of the imported PM. This is due to the particle size. In summary, ACD is more suitable for hydroponic cultivation of strawberry due to its lower air-filled porosity and higher container capacity compared to FCD. It is also better to increase the air-filled porosity to 15% or more by mixing PM with PL. 본 연구는 미숙성 상태의 코이어 더스트(non-aged coir dust, NACD)를 24주간 숙성시키면서 변화되는 물리성, 국내에서 유통되는 피트모스(PM)의 원산지 별 물리성 차이, 그리고 이들 두 종류 유기물에 대한 펄라이트(PL)나 버미큘라이트(VL)의 혼합 비율 조절이 물리성 변화에 미치는 영향을 조사하여 딸기 수경재배를 위한 기초 자료를 제시하고자 수행되었다. NACD와 비교한 숙성된 코이어 더스트(aged coir dust, ACD)의 물리성은 총 공극률은 큰 차이가 없는 반면 용기용수량은 59.6%에서 71.1%로 증가되고, 기상률은 30.1%에서 18.9%로 감소되었다. 각국에서 수입된 PM의 총 공극률은 에스토니아산 83.8%, 캐나다산 82.6%, 라트비아산 82.5%, 그리고 리투아니아산 81.8%였다. 용기용수량은 리투아니아산이 75%로 가장 높고, 캐나다산 73.1%, 라트비아산 71.8%, 에스토니아산 71.2%였지만, 기상률은 에스토니아산 12.5%, 라트비아산 10.7%, 캐나다산 9.5%, 그리고 리투아니아산 6.9%였다. NACD 또는 ACD에 버미큘라이트를 혼합한 경우 총 공극률이 낮아졌고, ACD에 버미큘라이트를 혼합한 경우 2차곡선 회귀적으로 기상률이 감소하였다(R2 = 0.6127, p ≤ 0.01). NACD 또는 ACD에 펄라이트의 혼합 비율을 증가시킬 경우 총 공극률이 감소하였으며, ACD에 펄라이트의 혼합 비율을 증가시킬수록 용기용수량이 2차곡선 회귀적으로 감소하였다(R2 = 0.5687, p ≤ 0.01). PM과 PL 또는 VL을 혼합한 후의 입경 분포에 영향을 받아 각각의 PM에 대하여 VL 또는 PL의 혼합 비율을 동일한 비율로 증가시켜도 총 공극률, 기상률 및 용기용수량은 PM 종류에 따라 변화 양상이 달랐다. 이상의 내용을 요약하면 ACD는 NACD에 비해 기상률이 낮아지고 용기용수량이 증가하여 수경재배용으로 더 적합하였고, 각각의 PM에 PL을 혼합하여 기상률을 15% 이상으로 높이는 것이 다년간 상토를 사용하는 국내 딸기 수경재배에 바람직하다고 판단된다.

Optimization of local porosity in the electrode as an advanced channel for all-vanadium redox flow battery

Yoon, Sang Jun,Kim, Sangwon,Kim, Dong Kyu Elsevier 2019 ENERGY Vol.172 No.-

<P><B>Abstract</B></P> <P>Experimental and numerical studies have been carried out to improve the flow distribution by optimizing the local porosity of the electrodes of the all-vanadium redox flow batteries (VFBs) to increase the energy efficiency at high current density. We control the local porosity by inserting extra layer of electrode at inlet and outlet, and the flow field of electrolyte is analyzed numerically. First, the flow field of electrolyte is analyzed numerically to understand distribution of electrolyte in the electrode. Then, the charge and discharge curve is analyzed to understand the effect of local porosity of electrode on the energy efficiency. At 50 mA/cm<SUP>2</SUP>, the energy efficiency is the highest when using electrode with uniform porosity. At 150 mA/cm<SUP>2</SUP>, however, the energy efficiency of the cell using the electrode with low porosity at inlet is similar to that using the uniform electrode which is 66.6%. Lastly, we suggest an empirical equation for optimal local porosity distribution of the electrode according to current density. Using the empirical equation, we can increase the energy efficiency of the cell to 67.7% at 150 mA/cm<SUP>2</SUP>. This study shows the possibility of increase of the energy efficiency of VFBs by controlling local porosity of the electrode.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Control of local porosity of electrode in all-vanadium redox flow batteries. </LI> <LI> Effects of local porosity studied by electrochemical experiment and flow simulation. </LI> <LI> Less porous inlet area helps cell performance at high current density and flow rate. </LI> <LI> Increasing active area at inlet can improve the battery performance. </LI> </UL> </P>

다공성 개념을 적용한 복합 상업공간 활성화에 관한 연구

강초이(제1저자) ( Cho Ie Kang ),유진형(교신저자) ( Jin Hyung Yoo ) 한국공간디자인학회 2015 한국공간디자인학회논문집 Vol.10 No.6

(Background and Purpose)Currently, commercial spaces are gradually developing into more complex spaces meeting recreational and cultural needs of the users. Such spaces allow the users to express their consumption tendencies (which emphasize the usefulness of such spaces) as well as cultural tendencies influenced by the improvement of standard of living and the lifestyles changes caused by the five-day workweek culture and the increase in leisure time. Thus, public areas in a commercial space are receiving attention and various changes are being introduced to satisfy the psychological desires of consumers. However, there has been a continuous dispute over the effectiveness of commercial spaces due to the changes in their interiors that create a gap between those spaces, and due to the spatial changes that undermine the human-space relationship. Therefore, using the concept of porosity as an alternative approach to revamp complex commercial spaces , this study analyzes the newly dormant complex commercial spaces and suggests sustainable elements to be incorporated, by analyzing porous characteristics of the existing complex commercial spaces. This way, this study offers solutions to the detected problems. (Research method) First, the concept, characteristics, and components of complex commercial spaces were analyzed. Furthermore, the role of porosity in complex commercial spaces was examined according to a theoretical understanding of the concept and characteristics of porosity. Ten key spatial characteristics of porosity were selected based on which, the relationship of porosity with complex commercial spaces was established. Subsequently, the methods to revamp complex commercial spaces were suggested and applied to actual cases to test their effectiveness. Among several domestic and foreign complex commercial spaces, the ones that showed the characteristics of porosity, were undergoing a process of revamp, and enabled smooth communication with the users, were selected for a theoretical case analysis. By investigating complex commercial spaces in domestic metropolitan areas and foreign locations in the U.S.A. and Japan, the spatial components and characteristics of porosity were examined. Finally, the analysis findings were extracted as follows . (Results) It was found that domestic complex commercial spaces had various purposes, but their use was limited because of the vertical traffic flow system and the difficulty in approaching and attracting users. Furthermore, those spaces were inadequately connected with surrounding spaces, and hence were hard to use. To solve these problems, it is necessary to introduce a horizontal traffic line system and porous spaces. Foreign spaces, which were planned according to this idea, are considerably more functional and porous than the domestic spaces. (Conclusions) In conclusion, planning complex commercial spaces that are characterized by the spatial components and are based on the concept and characteristics of porosity, would help to improve the connectivity among the spaces and revamp them by giving them special spatial characteristics that set them apart from other spaces.

Evaluation of geotechnical properties of saturated soil using dielectric responses

Man-Il Kim,Byung-Gon Chae,Makoto Nishigaki 한국지질과학협의회 2008 Geosciences Journal Vol.12 No.1

In the field of geotechnical environment, physicalparameters of soil such as volumetric water content, degre of sat-uration, porosity and effective porosity are important hydrologicalfactors. Especialy, these parameters can be aplied to the analysissubstances into the ground by rainfall. In the case of a landslideinduced by heavy rainfall, landslide monitoring is one of impor-tant technologies that detects the distribution of volumetric watercontent, wetting front movement, and infiltration characteristicsfor the earth materials. The infiltration of water mainly occursthrough pores of porous media. Infiltration of fluid substances iscontrolled by the connectivity of pore spaces. Therefore, it isexplained by the concepts of porosity and effective porosity. In thisstudy, the applicability of dielectric methods and proposed dielec-oratory test is performed for measuring effective porosity of fullysaturated sand using the permittivity method. This study showedthat the ratios of effective porosity to porosity of saturated stan-dard sands and river sands were 0.856 and 0.843, respectively.Based on the experimental results, using the frequency domainreflectometry (FDR) and frequency domain reflectometry withvector network analyzer (FDR-V) systems, the relative effectiveporosity is almost over 85 % of the relative porosity in the satu-rated standard sands and river sands. Consequently, the dielectricthe physical parameters of saturated soil. Moreover, this dielectricmethod can contribute to estimate porosity and effective porosityof saturated porous media because it is easier and faster than theprevious in-situ methods.

시멘트 모르타르의 공극률과 내구특성과의 관계에 대한 실험적 연구

박상순(Park Sang Soon),권성준(Kwon Seung-Jun),김태상(Kim Tae Sang) 대한토목학회 2009 대한토목학회논문집 A Vol.29 No.2A

콘크리트의 공극률은 유해인자의 주된 이동통로가 될 뿐 아니라, 수분을 보유할 수 있는 역할을 하게 되므로, 열화물질 이동 저항성을 평가할 수 있는 주된 지표가 되고 있다. 내구성에 대한 연구가 중요해짐에 따라, 공극구조를 기본으로 하는 열화모델이 최근 들어 개발되고 있으며, 공극구조와 내구특성간의 관계는 매우 중요하게 평가되고 있다. 본 연구는 5가지의 다른 물-시멘트비(40%, 45%, 50%, 55%, 60%)를 가진 시멘트 모르타르를 제조하여, 공극률을 포함한 다양한 내구성 실험을 수행하였다. 내구특성 실험은 기본적인 압축강도 실험을 포함하여, 투기성 실험, 염화물 확산계수 실험, 흡수율 및 수분 확산계수 실험 등이 수행되었다. 평가된 내구성 실험결과는 물-시멘트비와 공극률에 따라 분석되었다. 공극률이 1.45배 높아질수록, 강도는 0.6배 수준으로 감소하였으며, 투기성, 염화물 확산계수, 흡수율, 수분확산계수는 각각 2.3배, 2.1배, 5.5배, 그리고 3.7 수준으로 증가하였다. 이러한 내구특성 변화율은 높은 상관성을 보이며, 공극률에 따라 선형적으로 변화함을 알 수 있었다. 한편, 실험결과와 문헌분석을 통하여, 목표내구성능을 설정하였으며, 이에 따라서 고내구성 콘크리트를 위한 공극를을 제안하였다. The porosity in porous media like concrete can be considered as a durability index since it may be a routine for the intrusion of harmful ions and room for the keeping moisture. Recently, modeling and analysis techniques for deterioration are provided based on the pore structure with the significance of durability and the relationship between porosity and durability characteristics is an important issue. In this paper, a series of mortar samples with five water to cement ratios are prepared and tests for durability performance are carried out including porosity measurement. The durability test covers those for compressive strength, air permeability, chloride diffusion coefficient, absorption, and moisture diffusion coefficient. They are compared with water to cement ratios and porosity. From the normalized data, when porosity increases to 1.45 times, air permeability, chloride diffusion coefficient, absorption, and moisture diffusion coefficient decrease to 2.3 times, 2.1 times, 5.5 times and 3.7 times, respectively, while compressive strength decreases to 0.6 times. It was evaluated that these are linearly changed with porosity showing high corelation factors. Additionally, intended durability performances are established from the test results and literature studies and a porosity for durable concrete is proposed based on them.

Simulation of Pore Interlinkage in the Rim Region of High Burnup $UO_2$Fuel

Koo, Yang-Hyun,Oh, Je-Yong,Lee, Byung-Ho,Cheon, Jin-Sik,Joo, Hyung-Koo,Sohn, Dong-Seong Korean Nuclear Society 2003 Nuclear Engineering and Technology Vol.35 No.1

Threshold porosity above which fission gas release channels would be formed in the rim egion of high burnup UO$_2$ fuel was estimated by the Monte Carlo method and Hoshen-Kopelman algorithm. With the assumption that both rim pore and rim grain can be represented by cube, pore distribution in the rim was simulated 3-dimensionally by the Monte Carlo method according to porosity and pore size distribution. Then, using the Hoshen-Kopelman algorithm, the fraction of open rim pores interlinked to the outer surface of a fuel pellet was derived as a function of rim porosity. The simulation showed that porosity of 24-25% is the threshold above which the number of rim pores forming release channels increases very rapidly. On the other hand, channels would not be formed if the porosity is less than about 23.5%. This is consistent with the observation that, for porosity less than 23.5%, almost no fission gas is released in the rim. However, once the rim porosity reaches beyond 25%, extensive open paths would be developed and considerable fission gas release would start in the rim.