• 한국환경과학회지
• /
• 제25권6호
• /
• pp.889-895
• /
• 2016

In Danseong-myeon (myeon is a subdivision of), Sancheong-gun, and Sugok-myeon, Jinju City, pot seedling culture was used at the rates of 100% and 62%, respectively. Root restriction seedling culture was used relatively more frequently than pot seedling culture in Yangchon-myeon, Nonsan City, Guryong-myeon, Buyeo-gun, and Wolsan-myeon, Damyang-gun. Open-field seedling culture was used at the rates of 80% and 54% in Samnangjin-eup (eup is a subdivision of a gun), Miryang City and Ssangnim-myeon, Goryeong-gun, respectively. In Danseong, Sancheong, and Sugok, Jinju, granite soil was used as the medium for pot seedling culture at the rates of 90% and 80%, respectively. In Yangchon, Nonsan, Wolsan, Damyang, and Ssangnim, Goryeong, commercial bed soil and coir dust were used for seedling culture at the rates of 73%, 64%, and 60%, respectively. At the main production sites, the use of granite soil for seedling culture, highest rate in 2000-2005, continued to decrease; in 2011-2013, granite soil was used at the rate of 37%, while commercial bed soil and coir dust were used at the rates of 32% and 14%, respectively. The bulk density of commercial bed soil, expanded rice hulls, and coir dust was $0.11-0.16g/cm^{-3}$. Coir dust was the lightest material but had the highest and, 36.7% and 21.8%, respectively. In sandy loam soil and granite soil was low. The pH of all growth media was between 5.4 and 7.0, and the values were in the range of $0.15-0.66dS{\cdot}m^{-1}$. However it was necessary, to adjust the pH levels and enhance the of expanded rice hulls, sandy loam soil, and granite soil. Similarly, the fertilizer concentration and air permeability of coir dust need to be adjusted.

• 대한토목학회논문집
• /
• 제29권1B호
• /
• pp.63-71
• /
• 2009

교각 세굴 방지를 위해 사석보호공을 설치하는 경우 하상의 유사이탈로 인한 보호공의 침하현상이 발생할 수 있으며 따라서 사석층과 하상 사이에 필터층의 설치가 반드시 필요하다. 하지만 국내의 명확하지 않은 필터설치 기준과 설치를 위한 기술적 어려움 그리고 고가의 공사비와 같은 문제점으로 인해 현장에서는 필터 없는 사석보호공을 주로 시공하고 있다. 이에 본 연구는 다양한 조건의 사석 포설두께, 접근 유속, 사석과 하상토의 입경을 갖는 수리실험을 통해 필터층이 없는 사석보호공의 침하량을 정량적으로 측정 및 분석하였으며 실험 결과, 접근유속이 증가할수록, 하상토의 입경이나 포설두께가 감소 할수록 최대침하량은 증가하는 양상을 보였고 일정 시간 후에는 침하량이 최대값에 도달하여 유사이탈이 더 이상 발생하지 않음을 알 수 있었다. 또한 본 논문에서 수행된 실험결과 자료들을 최종적으로 종합하여 하상토 입경 계수가 포함된 필터층 없는 사석보호공의 무차원 침하량 산정식을 제안하였으며 이러한 연구 결과들은 추후 필터층 없이 시공되는 사석 보호공의 침하 안정성 평가를 위한 지표로 활용될 수 있을 것이다.

• 공업화학
• /
• 제9권6호
• /
• pp.852-856
• /
• 1998

유동층 연소로에서 압력 요동의 통계적 처리 방법을 이용하여 충전물질의 유동층 거동에 대한 영향을 분석하였다. 실험은 내경이 6.7cm인 유동화 장치에서 수행하였고, 실험변수는 입자크기 및 분포, 유동화가스, 유동층의 aspect ratio(L/D), 충전물 등이다. 충전물질은 스크린 충전물질을 사용하였고, 압력 요동 특성은 차압 전달기로 측정하였다. 측정 압력 요동 특성치는 평균값과 표준편차, power spectral밀도 합수의 주진동수 등이다. 압력요동의 표준 편차는 압력 측정 tap의 반경 방향에 거의 영향을 받지 않았으며, 압력 측정 tap의 축방향에서는 충전물이 없는 경우 가스분산판 약 4.5cm 이상에서는 거의 일정하다. 충전물의 크기가 증가할수록 주진동수는 감소하는 경향이 나타났으며, 충전물의 양이 10% 부근에서 주진동수가 가장 큰 변화값을 나타내었다. 압력 요동의 표준 편차는 유동층 연소로의 거동을 해석하고 유동화 현상을 설명하는데 효과적이며, 압력 요동의 특성들은 충전물질에 많은 영향을 받았다.

• 한국화재소방학회논문지
• /
• 제32권2호
• /
• pp.24-29
• /
• 2018

스프링 침대 매트리스의 화재안전성을 향상시키기 위한 방안으로 냉각재료(물)을 포함한 냉각프레임을 제작하여 침대 매트리스 아래 또는 침대 매트리스와 침대 매트리스 받침대 사이부분에 냉각프레임을 설치하여 냉각프레임 설치 유무에 따른 실물규모 화재시험을 실시하였다. 시험 초기(약 3분)에는 비슷한 화재성상을 보이나 이후에는 냉각프레임이 없는 경우는 급격한 화재성장이 확인 되었으며, 냉각프레임이 있는 경우는 성장되지 않고 쇠퇴가 진행되었다. 침대 매트리스 상단표면에서의 화염전파는 반원방향으로 유사하게 진행되었으며, 평균 화염전파속도는 약 0.005 m/s 분석되었다. 최대화염높이는 냉각프레임이 없는 경우 약 2.7 m, 냉각프레임이 설치된 경우 약 1.8 m로 분석되었다. 또한 최대열방출율(Heat release rate)은 냉각프레임이 없는 경우는 약 740 kW, 냉각프레임이 설치된 경우는 약 400 kW 측정되었다. 결과적으로 냉각프레임 설치를 통해 침대 매트리스 화재시 화염높이 및 열방출율이 저감되는 것으로 확인되었다.

• Carbon letters
• /
• 제15권3호
• /
• pp.198-202
• /
• 2014

Amorphous agglomerates of carbon nanospheres (CNS) with a diameter range of 10-50 nm were synthesized using the solution combustion method. High-resolution transmission electron microscopy (HRTEM) revealed a densely packed high surface area of $SP^2$-hybridized carbon; however, there were no crystalline structural components, as can be seen from the scanning electron microscopy, HRTEM, X-ray diffraction, Raman spectroscopy, and thermal gravimetric analyses. Electrochemical and thermo catalytic decomposition study results show that the material can be used as a potential electrode candidate for the fabrication of energy storage devices and also for the production of free hydrogen if such devices are used in a fluidized bed reactor loaded with the as-prepared CNS as the catalyst bed.

• 한국전기전자재료학회논문지
• /
• 제26권9호
• /
• pp.662-668
• /
• 2013

Reported here are results of the mechanical and electrical properties of both of intact and thermally degraded epoxy-coated copper busducts that are made by fluidized bed process. To elucidate and compare the properties mentioned above, electrical breakdown by thermal and water aging, v-t characteristic, bending test, impact test and cross cut test are carried out. Although the performance of electrical and mechanical properties are gradually decreased in increasing the severe conditions such as temperature, aging time, and so forth, sample C has a better performance in both mechanical and electrical properties.

• 한국정밀공학회지
• /
• 제32권9호
• /
• pp.765-771
• /
• 2015

In an Additive Manufacturing (AM) system emplying the Powder Bed Fusion (PBF) system, polyamide-12 powder is currently recognized as the general material used. The Polyamide-12 powder's properties include an average particle size of 58 $58{\mu}m$, a density of 0.59 g/cm3, and melting point of $184^{\circ}C$, and can also be to used coat materials for metal powder. For this reason, the sintering process is similar to the polymer powder and polymer coated metal powder process, except during the post-process. The polyamide-12 powder has some disadvantages such as its high cost and the fact that it can only be used for the provided equipment from the maker. Therefore, this study aims to perform the applicability of new material, polymer and polymer coated metal, to the PBF system.

• 한국환경과학회지
• /
• 제22권5호
• /
• pp.563-570
• /
• 2013

Roughness coefficient was computed for review of applicability based on measurement of the representative grain diameter reflecting channel characteristics of Han Stream. After field survey, collection of bed material, and grain analysis on the collected bed material, roughness coefficient was computed using representative grain and existing empirical equation for roughness coefficient. Value of roughness coefficient calculated using equation by Meyer-Peter and Muller (1948) was 0.0417 for upstream, 0.0432 for midstream, and 0.0493 for downstream. As a result of comparing the computed roughness coefficient to other empirical equations for review of applicability, the coefficient was larger in Strickler (1923) equation by 0.006. Smaller coefficient was shown by Planning Report for River Improvement Works. Equation by Garde and Raju (1978) was larger by 0.004, and equations by Lane and Carlson (1953) and by Meyer-Peter and Muller (1948) were larger by 0.001. Such precise roughness coefficient is extremely important when computing the amount of flood in rivers to prevent destruction of downstream embankments and property damages from flooding. Since roughness coefficient is a factor determined by complicated elements and differs according to time and space, continued management of roughness coefficient in rivers and streams is deemed necessary.

• 한국지반공학회:학술대회논문집
• /
• 한국지반공학회 2010년도 추계 학술발표회 2차
• /
• pp.192-199
• /
• 2010

This research produced internal model tester ($2.0m{\times}2.0m{\times}1.0m$) to evaluate the field application of Paju Unjeong District water recycling system for small streams eco-friendly river bed disparity method for the first time in Korea and conducted comparative analysis of the Paju Unjeong District water recycling system field test results and infiltration rate result of internal tests by each rainfall intensity following surface material. Infiltration rate result of internal tests concrete pavement by rainfall intensity following surface material, asphalt pavement, bentonite mate, stabilized soil construction and mixed soil construction manifested low infiltration rate. On the contrary, compaction soil, grassland and water permeable packaging materials resulted in significant amount of infiltration rate. As for the field permeability test results, they were manifested similar tendency as indoor permeability test results and they satisfied the standard for standard of water permeability of domestic disparity facility (less than $1.0{\times}10-7cm$/sec). As compaction rate increased, unconfined compression strength increased as well while coefficient of water permeability decreased.

• 한국세라믹학회지
• /
• 제52권2호
• /
• pp.154-158
• /
• 2015

This paper investigates the reaction rates of $CO_2$ that stores carbonation through comparing the carbonation behavior between $Ca(OH)_2$ and fly ash with circulating fluidized bed combustion (CFBC) containing a large amount of free CaO. Because fly ash with CFBC contains abundant free CaO, it cannot be used as a raw material for concrete admixtures; hence, its usage is limited. Thus, it has been buried until now. In order to consider its reuse, we conduct carbonation reactions and investigate its rates. X-ray diffraction (XRD), thermogravimetric/differential thermal analysis (TG/DTA), and X-ray fluorescence (XRF) are conducted for the physical and chemical analyses of the raw materials. Furthermore, we use a PH meter and thermometer to verify the carbonization rates. We set the content of the fly ash of CFBC, $Ca(OH)_2$, $CO_2$ flow rate, and water to 100 ~ 400 g, 30 ~ 120 g, 700 cc/min, and 300 ~ 1200 g, respectively, based on the content of the free CaO determined through the TG/DTA analyses. As a result, the carbonization rate of the fly ash with CFBC is the same as that of $Ca(OH)_2$, and it tends to increase linearly. Based on these results, we investigate the carbonization behavior as a function of the free CaO content contained in the raw material.