• Proceedings of the Korea Society for Energy Engineering kosee Conference
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• 1996.10b
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• pp.91-97
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• 1996

Bench Scale급 가스화기를 이용하여 중국 대동탄에 대하여 O2/coal 비, 가스화기 운전 압력에 따른 가스화 특성을 조사하였다. 가스화기를 가압하는 방법으로 메탄과 산소의 버너를 이용하여 운전 압력까지 단시간 내에 가압하는 방법을 정립하였다. 가스화기 압력은 상압으로부터 10기압까지 실험을 실시하였으며, 10기압, 반응온도 1350-140$0^{\circ}C$, O2/coal 비(as-fed 기준) 0.9의 운전조건에서 탄소전환률 90%이상, 냉가스효율 60%, 그리고 heating value 1800 Kcal/N㎥ 정도의 생성가스 특성을 얻을 수 있었다.

• Applied Chemistry for Engineering
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• v.29 no.2
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• pp.237-243
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• 2018

The surface chemistry of WCK-AC, WCN-AC and WCZ-AC which are activated carbons prepared from waste citrus peel using KOH, NaOH, and $ZnCl_2$ as activating chemicals were investigated. Also the relationships between the adsorption capacities of the target gases such as acetone, benzene and methyl mercaptan (MM) by the prepared activated carbons and the pore characteristics of each activated carbon were examined. According to XPS analysis of the prepared activated carbons, graphite and phenolic were the main surface functional groups of C1, and the sum of phenol, carbonyl and carboxyl groups increased in the order of WCK-AC > WCN-AC > WCZ-AC. The breakthrough curves obtained from the adsorption experiments for the three target gases in the fixed bed adsorption reactor were well simulated by the empirical equations proposed by Yoon and Nelson. The adsorption capacity for acetone, benzene and MM was larger for activated carbons with the larger sum of surface functional groups. The larger the specific surface area and the pore volume of activated carbons and the smaller the pore size, the better the adsorption performance. In particular, the specific surface area was the best criterion for the adsorption performance of activated carbons used in this study.

• Journal of the Korea Institute of Building Construction
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• v.20 no.1
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• pp.43-51
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• 2020

The main purpose of protective facility for small military unit is to provide the protection of not all the weapons system but the near-miss bullet in Korean army. In particular about the small caliber bullets, especially KM80 in Korea, there were many studies that both of the experiential and structural design methods dose not reflect enough the military threat. For that reason, a new equation to calculate effective anti-piercing depths for RC slabs against small caliber bullets is proposed in earlier research with actual shooting test. But, the test only considers the strength of concrete without the thickness of concrete, types of aggregate, the angle of yaw of bullet, high-strength concrete, etc. Therefore, this study evaluated the ballistic resistance performance by thickness and proportion of magnetic aggregate of concrete. As a result, we identified two major statistical estimations that the error of piercing depth by the angle of yaw of bullet could be cancelled by barrage and the thickness and proportion of magnetic aggregate of concrete dose not effect on the protection ability of concrete structure.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.31 no.3D
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• pp.413-420
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• 2011

An experiment was conducted to suggest the road pavement material combining wooden chip crushed from little useful roots and branches from logging sites or wood waste from construction sites with urethane resin. For the specimen, the mass ratio of urethane resin to construction wood waste chip/lumber waster chip was set to three different levels of 0.5, 0.75, and 1.0, which was measured, mixed with mixer, and molded; 7 days after, tensile strength test, elasticity test using golf balls and steel balls, permeability coefficient measurement, and flammability test were executed. As the result, the tensile strength of the specimen at the dry state in the air exhibited the range of 0.2-1.1MPa, and there was no change after 7 days of aging. When submerged in water, however, the strength was partially diminished; the diminishing rate was greater for less urethane resin usage, and therefore it appears desirable to set the mass ratio of resin to the wood waste chip over 0.75 to consider the moisture intrusion by precipitation and such. As the result of elasticity test, the GB and SB coefficients of the specimen using wood waste chips and urethane resin were measured to be low at below 20%, exhibiting excellent elasticity as road pavement material. Also, the permeability coefficient was over 0.5mm/sec for specimens of all combinations, exceeding the standard value required after construction for permeable pavement material, and the flammability of wood-type pavement material was evaluated to have no practical issues.

• Korean Journal of Construction Engineering and Management
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• v.10 no.5
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• pp.123-134
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• 2009

Since 1970s, urethane waterproofing method is broadly used in rooftops, underground spaces, and sports stadium for its outstanding ultraviolet blockage, watertightness, and elasticity. However, development of slippage-resistance and endurance, improvement of function considering convenience and visually pleasing of users, urethane waterproofing method is necessary, since rooftops and underground spaces have slippage and external force risks. Therefore, many improved waterproofing methods are being developed and, recently, embo-thane waterproofing method, which applies embo-spray coating system, has been developed. This paper explains exposure, nonexposure, and floor-material of embo-thane waterproofing method, and then perform experimental study for comparison with urethane waterproofing method about tensile strength, coefficient of expansion, performance of bond, anti-abrasion, and slippage-resistance. In addition, the performance index was presented for the superiority of embo-thane waterproofing method compared to urethane by setting up evaluation criteria considering not only physical performance but also design side of embo-thane waterproofing method, and Value Analysis applying AHP. Also for an assessment considering uncertain result, Monte Carlo Simulation Method was used to operate reliability analysis through statistic approach method.

• Economic and Environmental Geology
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• v.57 no.3
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• pp.281-292
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• 2024

North Korea relies heavily on coal as the primary energy source, playing an important role in all energy demand sectors except for the transportation sector. Approximately half of the total electricity is generated through coal-fired power plants, and coal is used to produce heat and power for all industrial facilities. Furthermore, coal has been a significant contributor to earning foreign currency through long-term exports to China. Nevertheless, since the 1980s, indiscriminate mining activities have led to rapid depletion of coal production in most coal mines. Aging mine facilities, lack of investment in new equipment, shortages of fuel and electricity, difficulties in material supply, and frequent damage from flooding have collectively contributed to a noticeable decline in coal production since the late 1980s. North Korea's coal deposits are distributed in various geological formations from the Proterozoic to the Cenozoic, but the most critical coal-bearing formations are Ripsok and Sadong formations distributed in the Pyeongnam Basin of the Late Paleozoic from Carboniferous to Permian, which are called as Pyeongnam North and South Coal Fields. Over 90% of North Korea's coal is produced in these coal fields. The classification of coal in North Korea differs from the international classification based on coalification (peat, lignite, sub-bituminous coal, bituminous coal, and anthracite). North Korean classification based on industrial aspect is classified into bituminous coal, anthracite, and low-grade coal (Chomuyeontan). Based on the energy factor, it is classified into high-calorie coal, medium calorie coal, and low-calorie coal. In North Korea, the term "Chomuyeontan" refers to a type of coal that is not classified globally and is unique to North Korea. It is a low-grade coal exclusively used in North Korea and is not found or used in any other country worldwide. This article compares North Korea's coal classification and the international coal classification of coal and provides insights into the geological characteristics, reserves, utilization, and research trends of North Korean coal resources. This study could serve as a guide for preparing scientific and industrial agendas related to coal collaboration between North Korea and South Korea.

• Journal of Korean Society of Environmental Engineers
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• v.30 no.5
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• pp.552-559
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• 2008

Three dimensional numerical analysis were performed to investigate the combustion characteristics in a tangentially fired pulverized coal boiler. The predicted values at the outlet of economizer for the gas temperature, O$_2$, NO, CO were been compared with the measured data. By using the actual operating conditions of the power plant, the distribution of velocity, gas temperature, O$_2$, CO, CO$_2$ and NO as well as the particle tracking in the boiler were investigated. Throughout the present study, the non-uniform distribution of flue gas temperature in front of the final superheater might be resulted from the residual swirl flow in the upper furnace of the boiler. The present analysis on non-uniform distribution of the gas temperature could provide the useful information to prevent the frequent tube failure from happening in the final superheater of the tangentially coal-fired boiler.

• Journal of the Korea Organic Resources Recycling Association
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• v.25 no.4
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• pp.51-60
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• 2017

Bottom ash(BA) from coal-fired power plants is burnt and remaining ash at high temperature. Since the BA is baked at high temperature, it is considered to be the same function as the elvan. Nowadays, the demand for mortar with far infrared rays, antibacteria, antifungus, deodorization, aridity and humidity function is increasing as the materials such as Hwangtoh(yellow soil) and elvan rather than general mortar. As a result of comparing the functionality of eco-friendly bio BA mortar with that of general mortar, the far infrared ray emissivity is about $0.02{\times}10^2W/m^2$ more and the deodorization function is about 26% or more. Even in the case of humidity control, BA motors showed about 1.8 times higher than general mortar, and more than 10% higher than the "good" standards of moisture absorption and damp proofing construction materials established by the Ministry of Land, Transport and Maritime Affairs.

• Journal of the Korea Institute of Building Construction
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• v.23 no.1
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• pp.1-9
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• 2023

This study is to analyze the cause of the defects in polyurethane waterproofing, a material commonly used on the roof of buildings, and to determine if it has a relation with the curing conditions of humidity and temperature and the moisture content of the base structure. As a result, it was confirmed that the waterproofing coating did not adhere when the moisture content of the base plate was 10% or more. When the temperature and humidity conditions were 20℃ and 80%RH, none of the properties deteriorate but when the temperature was 40℃, 60%RH, air bubbles were formed on the surface, and at 40℃ and 80%RH, the basic properties of the dry coating film were less than the KS F 3211 performance standard.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2009.11a
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• pp.339-343
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• 2009

The aim of the study was to investigate the statistical distribution of muzzle velocity of 155mm propelling charge K676 which is for the use of K9, a korean 155mm self-propelled artillery. A plenty of muzzle velocity data were collected from lot assessment test of propelling charge. The muzzle velocity of each test round is compensated by reference round. In the present work, the detailed statistical analysis of the muzzle velocity data is carried out using probability models including normal, Weibull 2-parameter and Weibull 3-parameter distributions. The results of goodness of fit test showed that the normal distribution described more appropriately the experimentally measured muzzle velocity data and the Weibull distribution is also applicable. The coefficient of variation showed that the mass production capability of each propelling charge lot has been maintained.