• Geomechanics and Engineering
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• 제30권6호
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• pp.517-524
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• 2022

Every year, millions of waste tires are discarded across the world. Storage of waste tires presents many problems such as fire threats, epidemics, and non-economic factors. Furthermore, the disintegration process of waste tires is not economical or practical due to its time-consuming, and disposal requirements. In this study, half-section waste tires (HSWTs) were integrated with high-density polyethylene (HDPE) pipes under different relative density conditions. The main aim of the study was to reduce the deformation values of embedded HDPE pipes in sandy soil and to evaluate the soil-pipe interaction. In comprehensive laboratory tests, half-section waste tires were integrated in two different ways: in the middle of the pipeline and along the pipeline. Accordingly, it was concluded that the effectiveness of waste tires reduces the deformation and bending moment values in the critical regions of pipes. As a result of reinforcement in the mid-point of the pipe defined as the most critical region, 52% and 36% less deformation was observed in the crown and springlines of the pipe, respectively. In addition, the bending moment values for the same critical section were determined to be 40% less in the crown and 28% less in the springline regions of the pipe.

• 한국식품과학회지
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• 제24권5호
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• pp.515-518
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• 1992

창평쌀엿의 최적 품질유지 조건을 찾고저 저장온도에 따른 관능검사, puncture force의 측정, 단면의 모양 변화 및 색도의 변화 등을 실험하고 종합 분석하여 본 결과 저장온도 $10^{\circ}C$까지는 품질의 변화를 찾기 어려웠다. $15^{\circ}C$ 이상에서는 품질특성이 나빠지기 시작하며 1주일 후에는 엿끼리 서로 들어붙기 시작하였다. 저장온도 $15^{\circ}C$ 이상에서는 각각의 엿이 서로 들어붙고, 먹을 때의 느낌도 좋지 못하며 치아에 들어붙어서 창평 쌀엿의 고유한 품질특성을 상실하였다. 따라서 창평쌀엿 고유의 품질을 최적상태로 유지하기 위한 한계 온도는 $12{\sim}13^{\circ}C$로 추정되었다.

• 전기학회논문지
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• 제64권9호
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• pp.1391-1397
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• 2015

Recently, various researches are conducted in the application of regenerative energy produced during the operation of an electric locomotive. Regenerative energy is produced by a generator in the brake procedure. The generator is operated by kinetic energy of an electric railroad using an electric motor. The process of producing regenerative energy varies with the current type of a railroad and its running condition. The quality of electric power can be improved and electric energy can be utilized effectively, especially in the use of an energy storage system (ESS). Thus, it is necessary to apply ESS into AC section and high speed railway. This study analyses the composition of the regenerative ESS equipment installed in Yong-Jeong sectioning post, operational principle, charge and discharge algorithm and energy efficiency. The analysis shows that CO2 emissions can be reduced about 0.5 ton per a day. In addition, ESS helps saving the energy and the compensation of the voltage drop caused by the operation of high speed train when it is installed at the end of the feeder section. The number of high speed train will be increased continuously related to the electrification rate. Therefore, applying the ESS to high speed railway is expected to solve the instability of the feeder voltage and the equipment capacity problem caused by the high speed trains.

• 한국가스학회지
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• 제6권4호
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• pp.33-39
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• 2002

[ $9\%$ ]니켈형 LNG 저장탱크는 내조와 외조가 독립적으로 초저온의 LNG를 저장할 수 있는 이중구조로 되어있다. 내조의 재료로는 초저온에서의 기계적 성질이 우수한 $9\%$니켈강을 사용한다. 그리고 내조파손에 의해 유출된 LNG를 저장할 수 있도록 콘크리트 외조가 설계된다. 코너프로텍션은 LNG 유출시 콘크리트 외조 코너부에 발생하는 열응력을 감소시키기 위해 단열재와 $9\%$니켈강 라이너를 시공하는 것을 말한다. 열하중에 의해 팽창과 수축이 반복되는 코너프로텍션의 경우 복잡한 응력상태가 발생되기 때문에 설계상의 어려움이 있다. 현재 한국가스공사에서 운용하고 있는 LNG탱크에는 TKK, KAWASAKI, WHESSOE사에서 설계한 코너프로텍션이 시공되어 있다. 본 논문에서는 유한요소해석을 통해 이들의 설계사양에 대해 ASME Section VIII Div. 2. Appendix 4에 기초한 건전성을 비교/분석하였다.

• 상하수도학회지
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• 제33권2호
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• pp.121-129
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• 2019

If sewage flows for an extended time at low velocities, solids may be deposited in the sewer. Sufficient velocity or tractive force should be developed regularly to flush out any solids that may have been deposited during low flow periods. This study aims to evaluate the periods (T) during which sewage flow greater than the minimum tractive force maintains on a spot in sewer pipe system with lower tractive force or lower velocity than expected in the design step, when a storage tank installed in a place upsteam pours water into the sewer. The effect to T of design factors of storage tank and sewer pipes was evaluated assuming the uniform flow in sewers. When the area of orifice in the storage tank is $0.062m^2$(or 0.28 m diameter), the maximum T of 31sec was maintained using the usually used preset range of values of several design factors. As the horizontal cross section of storage tank and water depth of storage tank and roughness in sewers increase, T linearly increases. Also, T linearly decreases as the diameter of a sewer pipe increases. Although T gradually decreases as the sewer pipe slope decreases to around 0.005, T decreases sharply when the slope is less than 0.003.

• Journal of Ecology and Environment
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• 제41권12호
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• pp.336-344
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• 2017

Background: Because of climate change, interest in the development of carbon pools has increased. In agricultural ecosystems, which can be more intensively managed than forests, measures to control carbon dioxide ($CO_2$) emission and absorption levels can be applied relatively easily. However, crop residues may be released into the atmosphere by decomposition or combustion. If we can develop scientific management techniques that enable these residues to be stocked on farmland, then it would be possible to convert farmlands from carbon emission sources to carbon pools. We analyzed and investigated soil respiration (Rs) rate characteristics according to input of carbonized residue of red peppers (Capsicum annuum L.), a widely grown crop in Korea, as a technique for increasing farmland carbon stock. Results: Rs rate in the carbonized biomass (CB) section was $226.7mg\;CO_2\;m^{-2}h^{-1}$, which was 18.1% lower than the $276.9mg\;CO_2\;m^{-2}h^{-1}$ from the red pepper residue biomass (RB) section. The Rs rate of the control was $184.1mg\;CO_2\;m^{-2}h^{-1}$. In the following year, Rs in the CB section was $204.0mg\;CO_2\;m{-2}h^{-1}$, which was 38.2% lower than the $330.1mg\;CO_2\;m^{-2}h^{-1}$ from the RB section; the control emitted $198.6mg\;CO_2\;m^{-2}h^{-1}$. Correlation between Rs and soil temperature ((Ts) at a depth of 5 cm) was $R^2=0.51$ in the RB section, which was higher than the other experimental sections. A comparison of annual decomposition rates between RB and CB showed a large difference, 41.4 and 9.7%, respectively. The results showed that carbonization of red pepper residues reduced the rates of decomposition and Rs. Conclusions: The present study confirmed that the Rs rate can be reduced by carbonization of residue biomass and putting it in the soil and that the Rs rate and Ts (5 cm) were positively correlated. Based on the results, it was determined that approximately $1.2t\;C\;ha^{-1}$ were sequestered in the soil in the first year and $3.0t\;C\;ha^{-1}$ were stored the following year. Therefore, approximately $1.5t\;C\;ha^{-1}year^{-1}$ are expected to be stocked in the soil, making it possible to develop farmlands into carbon pools.

• 한국식품저장유통학회지
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• 제19권6호
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• pp.873-881
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• 2012

본 연구에서는 참죽 순의 간장 절임 조건에 따른 품질 특성을 조사하였다. 그 결과 참죽 순의 pH 및 산도 변화는 감초를 첨가한 구간에서 조금 적게 감소하는 경향을 나타내었다. 가용성 고형분 함량 및 염도 변화는 저장 기간이 경과할수록 서서히 감소하는 경향을 나타내었다. 참죽 순의 색도 변화는 저장 기간이 경과할수록 간장에 의해 녹색에서 어두운 녹색으로 변화하는 경향을 나타내었다. 참죽 순의 조직감 변화는 특유의 특성에 따른 차이를 나타냈으며, 감초를 첨가한 구에서의 변화가 적은 것으로 나타났다. 그리고 관능적 특성은 P1-1구간에서 전반적으로 가장 높게 나타났다. 간장 절임액의 pH 및 산도 변화는 저장 기간이 경과할수록 감소하는 경향을 나타내었다. 가용성 고형분 함량 및 염도 변화는 크게 나타나지 않았으며, 설정된 조건에서 저장 기간 동안 미생물 변화는 나타나지 않았다. 이상의 결과에서 참죽 간장 절임액 조건 및 절임 기간 중 품질 변화에 관한 조건이 설정되어 참죽을 이용한 다양한 절임식품의 상용화가 가능 할 것으로 기대되었다.

• 한국안전학회지
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• 제28권6호
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• pp.49-56
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• 2013

The statistics of recent accidents in warehouses show that a heavy toll of lives were produced by various accidents, e.g. collision, overturn, fall, slip, exposure to harmful substances or environments, etc. Of significant concern amongst them is the collision, especially the collision between forklift and storage rack structure. Accordingly, this study focuses on behavioral characteristics of rack structure subjected to dynamic impact loading of a forklift. For this purpose, time-domain response analysis has been performed on a standard 2-bay six-story rack structure consisting of columns, beams and bracing members with perforated open section. In order to investigate the most critical scenario, the impact loads are applied in both down-aisle and cross-aisle directions, and the impact locations are also varied along the shelves of the palettes. In order to deal with storage distributions, three types of rack structures are further taken into account: original empty rack structure with no storage, half-loaded rack structure and fully-loaded rack structure. The numerical simulation results demonstrate that the dynamic characteristics of the rack structure are significantly dependent on the distribution of the storage goods and its natural period varies from 0.24sec to 1.06sec, approximately 4.4 times. Further, the parametric studies show that the forklift impact is most critical to the safety of the rack structure when it collides either at the base or at the top of the rack structure.

• Ecology and Resilient Infrastructure
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• 제3권4호
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• pp.294-301
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• 2016

금강의 지류인 치성천의 홍수범람이 빈번하게 발생하는 구간을 대상으로 하단배출형 가동보를 다단으로 배치하여 가동보 관리수위별 홍수조절 및 저류 효과를 기존 고정보의 설치 경우와 비교 분석하였다. 하단배출형 가동보 설치 지점에서의 첨두유량이 최대 97%가 감소하였고, 하류단 홍수위가 최대 82%가 감소하였다. 또한 하단배출형 가동보의 다단 배치로 구조물 상류구간에 저류와 분배 기능으로 저류량이 최대 463%가 증가하였다. 이러한 저류량과 하류단 첨두 홍수위, 유량의 관계를 통해 대상구간의 목표 저류량과 홍수 저감 수위를 위한 각 가동보의 관리수위 제안이 가능하다.

• Journal of Radiation Protection and Research
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• 제30권2호
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• pp.61-67
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• 2005

노심설계 해석체계로 사용하는 HELIOS-MASTER코드를 이용하여 SAMRT연구로 사용 후 핵연료 저장조에 대한 임계도 해석체계를 개발하였다. 저장조의 기하학적 모형에 대한 거시 단면적을 HELIOS코드를 이용하여 생산하고, 저장조의 3차원 모델에 대한 임계도를 MASTER코드로 평가하였다. 또한 3차원 MCNP계산을 통하여 HELIOS-MASTER체계를 이용한 임계도 평가의 타당성을 검증하였다 HELIOS-MASTER코드 체계를 이용한 임계도 해석결과가 약간 보수적인 방향으로 허용오차 범위 내에서 정확도를 유지하였다. HELIOS-MASTER 코드 체계는 3차원 연소계산이 가능하기 때문에 차후에 연소이력을 고려한 사용후 연료 저장조에 대한 임계해석에 유용할 것이다.