• Explosives and Blasting
• /
• v.34 no.1
• /
• pp.11-18
• /
• 2016

It is necessary to minimize ground vibration and noise due to blasting work in urban environment. The blast induced ground vibration and noise are generally generated by a portion of detonation energy, where most of the energy is utilized for rock breakage and movement of rock mass. Recently a blast method utilizing U-shaped steel charge holder was suggested to reduce the ground vibration without decreasing destructive power toward the free surface. In this study, single hole blasting utilizing U-shaped steel charge holder were simulated and the stress waves caused by the detonation of explosives were monitored using AUTODYN software. In order to examine the fragmentation efficiency of the U-shaped steel charge holder, one free face blasting models which adapt the blast induced stress waves were simulated by dynamic fracture process analysis (DFPA) code. In addition, the general blasting models were also simulated to investigate the fragmentation effectiveness of the U-shaped steel charge holder in rock blasting.

• Economic and Environmental Geology
• /
• v.38 no.6 s.175
• /
• pp.717-729
• /
• 2005

Peak cooling load of large buildings is generally greater than their peak heating load. Internal and solar heat gains are used fur selection of adquate equipment in large building in cold winter climate like Canada and even Korea. The cost of geothermal heat exchanger to meet the cooling loads can increase the initial cost of ground source heat pump system to the extend less costly conventional system often chosen. Thermal ice storage system has been used for many years in Korea to reduce chiller capacity and shift Peak electrical time and demand. A distribution system designed to take advantage of heat extracted from the ice, and use of geothermal loop (geothermal heat exchanger) to heat as an alternate heat source and sink is well known to provide many benifits. The use of thermal energy storage (TES) reduces the heat pump capacity and peak cooling load needed in large building by as much as 40 to $60\%$ with less mechanical equipment and less space for mechanical room. Additionally TES can reduce the size and cost of the geothermal loop by 1/3 to 1/4 compared to ground coupled heat pump system that is designed to meet the peak heating and cooling load and also can eliminate difficuties of geothermal loop installation such as space requirements and thermal conditions of soil and rock at the urban area.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.19 no.5
• /
• pp.577-586
• /
• 2018

In Korea, sustainability is mandatory in every field. University campuses are educational facilities that consume considerable amounts of energy. Therefore, many universities have tried to take advantage of the last opportunity to prepare students with sustainability and leadership. This study compared the green campus policy and evaluation criteria among Korea, US AASHE, UNEP, and ISCN-GULF to vitalize the green campus movement and suggest recent research data for the Korea green campus accreditation. The results are as follows: 1. new evaluation criteria need to be added to the certified green building total floor area ratio instead of adapting the G-SEED system in the Campus Resource & Environments category; 2. Korean Green Campus Evaluations need to be improved when expressing the campus individuality by choosing an increased number of credits and criteria; and 3. new evaluation criteria are required to secure the result, feedback, and products from curriculum updates in the Campus Education category.

• 한국신재생에너지학회:학술대회논문집
• /
• 2006.06a
• /
• pp.21-24
• /
• 2006

수소의 소규모 분산 생산 기술은 본격 적 인 수소 인프라가 도입되기 전에 연료전지 자동차의 수소 충전용이나 분산 발전형 연료전지의 수소 공급을 위해 필요하다. 생산 용량은 수소 기준으로 $20{\sim}100 Nm^3/hr$ 정도로 현재로선 천연가스의 수증기 개 질법이 가장 경제적인 공정으로 알려져 있다. 소규모 생산에 따른 열효율 저하를 줄이 기 위해 단위 공정들이 통합된 컴팩트 개질 시스템의 개발이 필요하다. 연료전지 자동차용 수소 인프라 조기 구축을 위하여 수소충전소 구축과 국산화 천연가스 수증기 개질기 개발을 병행하여 진행하였다. 수소 충전소 구축 부분은 충전소 부지 확보, 건물 건축, 각종 유틸리 티 설치의 토목 부분과 천연가스 개질형 수소 제조 유닛 설치, 수소 압축, 저장, 디스펜싱 시스템 설치를 포함하고 있으며 고압 설비에 대한 인허가 대응 및 안전대책 작업도 진행하였다. 구축된 수소충전소는 향후 연료전지 자동차 연계 실증 프로그램에 활용할 수 있다. 국산화 핵심 기술 개발을 위하여 열 및 시스템 통합 설계에 의 해 천연가스 수증기 개질기를 제작하고 내부 열교환 구조에 따른 개질기의 성능을 평가하였다. 개발된 개질기는 개질온도 $720^{\circ}C$, 수증기 대 카본 비 2.7의 운전조건에서 $23Nm^3/h$ 이상의 수소 생산이 가능하였으며 73% 이상의 개질 효율을 나타내었다. 개발된 천연가스 수증기 개질기는 향후 수소 정제용 PSA(Pressure Swing Adsorption) 시스템과 연계하여 수소충전소 국산화 엔지니어링 설계 패키지 개발의 핵심 기 술로 사용할 계획이다.시간 정도 운전한 후 시스템을 정지하였다 메탄 전환율과 일산화 탄소 농도, 열효율을 모니터링 하고 있으며, 현재까지 초기 성능을 그대로 유지하고 있다. 앞으로 일일시동-정지 운전 시험을 지속하면서 초기 시동 특성 및 부하 변동에 따른 응답 특성 개선, 그리고 연료전지와의 연계 운전을 실시할 예정이다 한다. 단위 전지 운전 온도 $130^{\circ}C$, 상대습도 37%의 운전 조건에서도 상당히 우수한 전지 성능을 보임에 따라 고온/저가습 조건에서 상용 Nafion 112 막보다 우수한 막 특성을 나타냄을 확인하였다.소/배후방사능비는 각각 $2.18{\pm}0.03,\;2.56{\pm}0.11,\;3.08{\pm}0.18,\;3.77{\pm}0.17,\;4.70{\pm}0.45$ 그리고 $5.59{\pm}0.40$이었고, $^{67}Ga$-citrate의 경우 2시간, 24시간, 48시간에 $3.06{\pm}0.84,\;4.12{\pm}0.54\;4.55{\pm}0.74 $이었다. 결론 : Transferrin에 $^{99m}Tc$을 이용한 방사성표지가 성공적으로 이루어졌고, $^{99m}Tc$-transferrin의 표지효율은 8시간까지 95% 이상의 안정된 방사성표지효율을 보였다. $^{99m}Tc$-transferrin을 이용한 감염영상을 성공적으로 얻을 수 있었으며, $^{67}Ga$-citrate 영상과 비교하여 더 빠른 시간 안에 우수한 영상을 얻을 수 있었다. 그러므로 $^{

• KIPS Transactions on Computer and Communication Systems
• /
• v.1 no.3
• /
• pp.143-150
• /
• 2012

A simulation methodology and corresponding program based on it is to be discussed for analyzing the effects of the networking operation of existing DHC system in connection with CHP system on-site. The practical simulation for arbitrary areas with various building compositions is carried out for the analysis of operational features in both systems, and the various aspects of thermal energy grids with connecting operation are highlighted through the detailed assessment of predicted results. The intrinsic operational features of CHP prime movers, gas engine, gas turbine etc., are effectively implemented by realizing the performance data, i.e. actual operation efficiency in the full and part loads range. For the sake of simplicity, a simple mathematical correlation model is proposed for simulating various aspects of change effectively on the existing DHC system side due to the connecting operation, instead of performing cycle simulations separately. The empirical correlations are developed using the hourly based annual operation data for a branch of the Korean District Heating Corporation (KDHC) and are implicit in relation between main operation parameters such as fuel consumption by use, heat and power production. In the simulation, a variety of system configurations are able to be considered according to any combination of the probable CHP prime-movers, absorption or turbo type cooling chillers of every kind and capacity. From the analysis of the thermal network operation simulations, it is found that the newly proposed methodology of mathematical correlation for modelling of the existing DHC system functions effectively in reflecting the operational variations due to thermal energy grids with connecting operation. The effects of intrinsic features of CHP prime-movers, e.g. the different ratio of heat and power production, various combinations of different types of chillers (i.e. absorption and turbo types) on the overall system operation are discussed in detail with the consideration of operation schemes and corresponding simulation algorithms.

• Korean Journal of Construction Engineering and Management
• /
• v.24 no.5
• /
• pp.12-21
• /
• 2023

Green remodeling proposed in the Korean New Deal is a project to build or remodel eco-friendly and energy-efficient buildings using renewable energy facilities and high-performance insulation for public buildings. The government intends to achieve the carbon emission reduction target by conducting green remodeling. Major overseas cities that conduct green remodeling are actively promoting technology support and promotion along with energy performance evaluation according to building characteristics, subsidies for private revitalization, and tax benefits. With this background, the analysis of the current status and problems of the green remodeling project was performed and the Activation factors of Green Remodeling were derived from survey results. This study suggested strategic measures such as a participation of civil society, promotion, and priority selection of administration and policy measures such as a leading role of the public sector, expanding support for the socially underprivileged, and financial support and tax benefits. And this study results are expected to be utilized as basic data to promote the green remodeling project.

• Journal of the Korean Geotechnical Society
• /
• v.33 no.12
• /
• pp.35-44
• /
• 2017

A large amount of recycled aggregates was produced and crushed from old buildings and pavements. In this study, when these aggregates are re-used in subbase or subgrade materials in near construction sites, their engineering characteristics caused by crushing are investigated in terms of permeability and shear strength. Three different sizes of aggregates (31.5-45.0 mm, 19.0-31.5 mm, 9.5-19.0 mm) and their mixtures, a total of 7 types of aggregates were used in compaction tests (modified D and B methods). After compaction tests, aggregates were sieved and analyzed with four different breakage factors ($B_{15}$, $C_c$, $B_{10}$, $B_r$). The D compaction method gave 2.0-8.0 times more crushable than B compaction method. The breakage factors for the largest size aggregate was 1.4-3.0 times higher than those of the smallest size aggregate. For aggregates with 5.6-9.5 mm sizes, the samples were prepared with $B_{15}$ of 1, 3, 10, 20, 30, 50, 60, and 70 for permeability and direct shear tests. As $B_{15}$ increased, the hydraulic conductivity decreased up to 1/22 for $B_{15}=50$. As $B_{15}$ increased from 1 to 50, the peak friction angle increased from $46.1^{\circ}$ to $54.5^{\circ}$. On the other hand, the friction angle decreased after $B_{15}=60$.

• Journal of the Computational Structural Engineering Institute of Korea
• /
• v.35 no.5
• /
• pp.277-286
• /
• 2022

The elastic and inelastic responses obtained from the experimental and analytical results of two RC building structures under the service level earthquake (SLE) and maximum considered earthquake (MCE) in Korea were used to weinvestigate the characteristics of the mechanisms resisting shear and torsional behavior in torsionally unbalanced structures. Equations representing the interactive effect of translational drift and torsional deformation on the shear force and torsional moment were proposed. Because there is no correlation in the behavior between elastic and inelastic forces and strains, the incremental shear forces and incremental torsional moments were analyzed in terms of their corresponding incremental drifts and incremental torsional deformations with respect to the yield, unloading, and reloading phases around the maximum edge-frame drift. In the elastic combination of the two dominant modes, the translational drift mainly contributes to the shear force, whereas the torsional deformation contributes significantly to the overall torsional moment. However, this phenomenon is mostly altered in the inelastic response such that the incremental translational drift contributes to both the incremental shear forces and incremental torsional moments. In addition, the given equation is used to account for all phenomena, such as the reduction in torsional eccentricity, degradation of torsional stiffness, and apparent energy generation in an inelastic response.

• Journal of agriculture & life science
• /
• v.51 no.5
• /
• pp.91-101
• /
• 2017

The in vitro experiment was conducted to ensure the supplemental level of spent Flammulina velutipes mushroom substrates(SMS) as an energy source in manufacturing of rye silage. Rye harvested at heading stage was ensiled with spent mushroom substrates of 0%(Control), 20%(R-20), 40%(R-40) and 60%(R-60) as fresh matter basis for 6week. The rumen fluid for preparation of in vitro solution was collected from two cannulated Holstein bulls fed a 40:60 concentrate:timothy diet. The experiment was conducted by 3, 6, 9, 12, 24, and 48 hrs of ncubation time with 3 replications. The silages were evaluated fermentation characteristics and dry matter digestibility(DMD) in vitro. The pH of in vitro solution was inclined to decrease with elapsing the incubation time, and that of the R-60 was significantly(p<0.05) lower than the other treatment at 48 hr of incubation. The microbial growth in vitro was inclined to increase with elapsing the incubation time, and that of the R-20 was significantly(p<0.05) greater than the Control at 48 hr of incubation. Gas production was greater(p<0.05) in the Control than the other treatments at 48 hr of incubation. In vitro dry matter digestibility(IVDMD) was higher with increasing the supplemental level of SMS, and was significantly(p<0.05) lower in the Control compared with other treatments throughout whole incubation time. The IVDMD for R-60 was the highest(p<0.05) among treatments at 24 hr and 48 hr of incubation. Considering of above results and the availability of SMS, SMS could be supplemented by 60% in fresh matter basis for rye silage fermentation.

• Clean Technology
• /
• v.18 no.1
• /
• pp.14-21
• /
• 2012

The pros and cons of green building thermal insulation materials and systems have been reviewed from traditional thermal insulation materials such as mineral wool and polyurethane to new thermal insulation materials like VIP and aerogel and future insulating VIM and DIM. VIPs and aerogels with very low thermal conductivity can use for green buildings to significantly increase residential area by reducing energy consumption. Aerogels can be produced as not only opaque and but also translucent forms, thus enabling a wide range of possible building application. For building applications, there are many properties to consider like building site adaptability and mechanical strength, fire protection, cost and environmental impact.