• Fire Science and Engineering
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• v.34 no.2
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• pp.14-21
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• 2020

This paper presents the study of a fire risk to the backside of two miniatures of ISO 9705 2/5 using a lightweight partition for indoor space division and reproduction of the ISO 9705 test. An SGP partition, stud partition, glass wool panel, urethane foam panel, sandwich panel, and glass partition were selected as the test specimens, which are frequently used in construction. According to the ISO 9705 test standard, stabilization was achieved using a measuring device that recorded data before the ignition of a burner and continued recording for 120 s thereafter. After ignition was achieved, the power was increased to 300 kW for 600 s and then reduced to 100 kW for 600 s. The specimens were subsequently observed for 180 s, and the fire risk to the backside and the fire pattern of the wall unit were analyzed. Owing to the amount of heat generated by the ignition source, the maximum temperature of the backside was observed to be 67.7 ℃ for the SGP partition, 55.1 ℃ for the stud partition, 52.4 ℃ for the glass wool panel, 727.4 ℃ for the sandwich panel, 561 ℃ for the urethane foam panel, and 630.5 ℃ for the glass partition. In the cases of the sandwich and urethane foam panels, the explosion of flammable gas occurred by virtue of fusion of the interior materials. The reinforced glass was fractured owing to the temperature difference between the heat- and nonheat-responsive parts. Ultimately, the fire risk to the nearby section room was deemed to be high.

• Clean Technology
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• v.21 no.3
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• pp.191-199
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• 2015

The SO_x emission from the ship diesel engines will do a negative influence to the human health and the environment. To reduce the negative environmental effect of the SO_x emission caused by the high traffic of ship movements, the SECA (SO_x emission control area) has been set on several province around world to carry out the severe emissions control and to meet the emissions control standard. To cut down the SO_x emission from the ships, the wet type scrubber is being used widely. In this work, we prepared a numerical model to simulate the spray type scrubber to study the motion of liquid droplets in the flow of the scrubber. For the analysis, the CFD (computational fluid dynamics) method was adopted. As a special topic of the study, we designed the wave plate type of mist eliminator to check the carry over of the uncontrolled water droplet to the exhaust. Numerical analysis is divided into two stages. At the first stage, the analysis was done on the basic scrubber without the mist eliminator, and then the second stage of analysis was done on the scrubber with the mist eliminator on several condition to check and compare with the basic scrubber. On the condition of the basic scrubber, 42.0% of the distributed water droplets were carried over to the exhaust. But by adding the designed droplet eliminator at the exhaust of the scrubber, only 3.4% of the distributed water droplets supplied to the scrubber was emitted to the atmosphere.

• Korean Journal of Plant Taxonomy
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• v.50 no.2
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• pp.154-165
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• 2020

Coastal regions are experiencing habitat changes due to coastal development and global warming. To estimate the future distribution of coastal plants on the Korean Peninsula due to climate change, the potential distribution of ten species of coastal plants was analyzed using the MaxEnt program. The study covered the eastern, western, and southern coastal areas of the Korean Peninsula. We used the distributional data of coastal plants of the East Asian region and the 19 climate variables of WorldClim 2.0. The future potential distribution was estimated using future climate variables projected from three general circulation models (CCSM4, MIROC-ESM, and MPI-ESM-LR), four representative concentration pathways (2.5, 4.5, 6.0, and 8.5), and two time periods (2050 and 2070). The annual mean temperature influenced the estimation of the potential distribution the most. Under predicted future distribution scenarios, Lathyrus japonicus, Glehnia littoralis, Calystegia soldanella, Vitex rotundifolia, Scutellaria strigillosa, Linaria japonica, and Ixeris repens are expected to show contracted distributions, whereas the distribution of Cnidium japonicum is expected to expand. Two species, Salsola komarovii and Carex kobomugi, are predicted to show similar distributions in the future compared to those in the present. The average potential distribution in the future suggests that the effects of climate change will be greater in the west and the south coastal regions than in the east coastal region. These results will be useful baseline data to establish a conservation strategy for coastal plants.

• Journal of Korean Tunnelling and Underground Space Association
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• v.19 no.1
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• pp.11-27
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• 2017

The road network system of major domestic urban areas such as city of Seoul was rapidly developed and regionally expanded. In addition, many kinds of life-lines such as electrical cables, telephone cables, water&sewerage lines, heat&cold conduits and gas lines were needed in order for urban residents to live comfortably. Therefore, most of the life-lines were individually buried in underground and individually managed. The utility tunnel is defined as the urban planning facilities for commonly installing life-lines in the National Land Planning Act. Expectation effectiveness of urban utility tunnels is reducing repeated excavation of roads, improvement of urban landscape; road pavement durability; driving performance and traffic flow. It can also be expected that ensuring disaster safety for earthquakes and sinkholes, smart-grind and electric vehicle supply, rapid response to changes in future living environment and etc. Therefore, necessity of urban utility tunnels has recently increased. However, all of the constructed utility tunnels are cut-and-cover tunnels domestically, which is included in development of new-town areas. Since urban areas can not accommodate all buried life-lines, it is necessary to study the feasibility assessment system for utility tunnel by urban patterns and capacity optimization for urban utility tunnels. In this study, we break away from the new-town utility tunnels and suggest a quantitative assessment model based on the evaluation index for urban areas. In addition, we also develop a program that can implement a quantitative evaluation system by subdividing the feasibility assessment system of urban patterns. Ultimately, this study can contribute to be activated the urban utility tunnel.

• Journal of the Korean Wood Science and Technology
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• v.44 no.5
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• pp.655-663
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• 2016

Increasing green house gas and it consequent climate change problems are discussed as a global issue. Accordingly, future local green house gas emission will increase up to 40% of the entire local green house gas emission and therefore, efforts to reduce the emission in construction industry is urgently required. Therefore, in this study, heating energy demand was analyzed by using the EnergyPlus simulation according to wood material finishes configuration. EnergyPlus has the entry for a variety of buildings and heating, ventilation, air conditioning (HAVC) system components, in particular buildings, air conditioning systems, and performs simultaneous integrated calculated through the feedback between the heat source unit, a verification program according to the ASHRAE Standard 140-2007 to be. The climate data for the simulation we used the data IWEC in Incheon and Gwangju provided by EnergyPlus. The analysis of simulation model was farm and fishing house standard design drawings: 2012, presented at the Korea Rural Community Corporation. The results of simulation of central region and southern region were effected by wood products of simulation model into the interior finish, exterior finish, windows, wooden structure. Also, it was confirmed that the reduced heating energy demand.

• Journal of the KSME
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• v.27 no.6
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• pp.504-514
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• 1987

복잡한 전자부품의 조립시에 필요한 열적 디자인에 관한 정보는 오래전부터 실험을 통하여 얻어지고 있다. 실험적 데이터를 이용하여 무차원 파라미터로 표시된 실험결과는 꼭 같지는 않지만 현상적으로는 비슷한 상황에 응용될 수 있다. 여기서는 학술문헌에 나타나 있는 자연대류에 관한 실험적인 상관관계식들과 프레임에 수직으로 꽂혀있는 균일가열 전자회로기판의 모델에서 얻어진 무차원 자료들을 비교하고자 한다. 대부분의 자료들은 수정채널 Rayleigh수(Ra")가 15~100범위에 속하며, 이러한 범위는 부품이 조밀하게 배치된 기관이 서로 좁은 채널을 이루고 있으며, 동시에 상당한 전력을 소비하고 있는 경우에 해당한다. Wirt와 Stutzman, Bar-Cohen과 Rohsenow의 일반상관관계식은 AT'||'&'||'T Bell 연구소에서 개발된 전자기기를 이용하여 수집한 실험데이터를 잘 표현하고 있으며 10 < Ra" <1,000범위에서 추천될 수 있다. 두개의 유사한 상관관계식과 비교할 때 상당히 좋은 예측을 보였으며 또한 Sparrow와 Gregg의 연구결과와도 잘 일치하므로 Ra" < 10인 경우에 Aung의 완전발달층류의 채널유동방식, Ra" > 1,000인 경우에는 Aung등의 단일 수직평판 근사식이 추천될 수 있다. Coyne의 알고리즘에 의한 계산치는 10

• Journal of the Korean earth science society
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• v.38 no.6
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• pp.405-420
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• 2017

We investigated the H I, He II and O III emission lines of the symbiotic star AG Peg, using the spectroscopic data secured at different phases in three periods at the Lick Observatory. We measured FWHM and the intensity of six O III Bowen lines and studied the efficiency of fluorescence mechanism. The mean FWHM of O III normal and Bowen lines observed during three time periods did not make much difference, while Bowen line intensities are about 4.0 times higher than the normal lines. Comparing the predicted and the observed ratios, we found that the observed intensities are higher than predicted intensities, except for O III ${\lambda}$ 3759.87. The O III ${\lambda}$ 3791.26 and 3754.67 intensity ratios observed only in 2001 are in good agreement with the predictions by Saraph and Seaton (1980). We obtained the Bowen efficiency parameter (R)=0.47 for 2002, but we could not find R for the other two periods of time. Because of this, based on the 2002 efficiency result, we calculated the intensity ratio of O III normal and Bowen lines relative to He II ${\lambda}$ 4685.68 and derive the efficiency variation with time period. The result showed that the efficiency is the highest in 1998 and the lowest in 2001. We conclude that the efficiencies with phase are caused by the electron temperature changes in the ionized gas. The efficiencies of AG Peg are likely to increase along with electron temperature. Our analysis results may be useful in understanding the physical conditions of the ionized shell in symbiotic star and the intensity ratio and efficiency variation.

• Journal of Korean Society of Forest Science
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• v.103 no.2
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• pp.264-269
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• 2014

The aim of this study was to determine the current distribution area of Robinia pseudoacacia habitat and to estimate its stand yield as well as its carbon stocks. In order to do so, the area of R. pseudoacacia distribution is obtained based on the large-scaled forest type map (1:5,000). Also, Weibull diameter distribution model is used to predict the yield of R. pseudoacacia stands. In addition, carbon emission factor is applied to calculate carbon stocks and removals. To obtain the stand yield of R. pseudoacacia, we developed estimation equation considering growth factors of the stand, e.g. mean diameter, the basal area, maximum and minimun diameter and etc. and tested it to ensure accuracy. Consequently, estimation equation derived from all growth factors have shown significance that could also be used for analysis. Site index was also established to determine the productivity of the forestland that later turned out to be ranging from 16 to 22. Based on these results, stand yield tables were drawn up. R. pseudoacacia is widely distributed in inland areas of Gyeongsang, Chungcheong and Gyeonggi provinces which covers total area of 26,770 ha. And when it is converted into carbon stocks, it amounts to 2,517,598tC with annual carbon uptake of 3.76tC/ha which is comparable to Querqus species that is known to storer large amounts of carbon. Therefore, R. pseudoacacia is also expected to serve as a viable carbon pool that would contribute to the mitigation of climate change. Furthermore, stand yield tables, an outcome of this survey would assist not only in proper management but also in sustainable management policy of R. pseudoacacia.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.46 no.2
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• pp.150-158
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• 2018

Numerical simulation and experimental study on the thermal flow field of the micro turbojet engine have been carried out for the purpose of developing infrared reduction technology for aircraft. A circular basic nozzle and five rectangular nozzles with different aspect ratio were considered. The conditions for CFD analysis were derived from the analysis of the engine performance. The temperature distribution of the nozzle plume was measured using a temperature sensing system. The thrust of the rectangular nozzle with the aspect ratio 5 was reduced about 1.8% compared to the circular nozzle, and the thrust decreased with increasing the aspect ratio of the nozzle. In the case of thermal flow field, it was observed that, as the aspect ratio increases, the exhaust plume in the experiment was formed wider than in the CFD analysis.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.5 no.4
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• pp.335-345
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• 2000

Physical and acoustic properties of the Southeastern Yellow Sea Mud (SEYSM) of Korea were studied by using 10 piston cores. The data were also compared with mudbelt sediments in the South Sea and the East Sea (southeastern inner shelf) of Korea. The sediments were mainly composed of homogeneous silt. Sandy mud and mud were minor components. The major source of sediment in the study area is probably the Keum River. Finegrained sediments discharged from the river are transported southward by coastal current, resulting in a gradual southward increase in porosity and a decrease in wet bulk density and sound velocity. The mean grain size especially appears to be the most important variable to determine the physical properties and velocity. The variations of physical properties with burial depth are dependent more strongly on sediment texture (especially, silt content) than compaction and/or consolidation. Correlations between the physical properties and the sediment texture show slight deviations from those of the East Sea and the South Sea of Korea in spite of similar pattern within the limiting values. This is probably due to the differences in silt contents, sedimentary environments, mineral compositions, and gas contents.