• Economic Analysis
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• v.26 no.2
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• pp.72-113
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• 2020

This study investigates the relationship between mineral exports to China, North Korea's most important source of foreign currency acquisition, and its imports of various items from China from the first quarter of 1995 through to the third quarter of 2019. The results from a cointegration analysis suggest that there exists a long-run equilibrium relationship between mineral exports and imports of food, fuel, and some intermediate goods, such as industrial supplies, parts, and accessories. The results from a vector autoregression using first-differenced variables indicate that the short-run relationship between mineral exports and imports is different between the period before and after the third quarter of 2010. Prior to structural changes, i.e., before the third quarter of 2010, import shocks affected mineral exports. However, after the third quarter of 2010, an increase in mineral exports led to an increase in the import of vehicles, intermediate goods, and luxury goods. This paper shows both the possibilities and the limits that mineral exports can contribute to North Korea's economic growth. The results, which show that mineral exports have a long-run relationship with intermediate goods, such as industrial supplies, parts and accessories, imply that mineral exports to China could have a positive effect on the North Korean economy. However, the fact that mineral exports do not have any significant effect on the import of machinery and equipment, which helps the accumulation of capital formation, shows that mineral exports have a limited effect on inducing long-term growth in the North Korean economy.

• Journal of Space Technology and Applications
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• v.3 no.1
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• pp.26-43
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• 2023

As Korean first lunar probe, Danuri, succeeded in entering lunar orbit, Korean new space exploration plans such as Mars exploration can be expected. Korean space exploration payload is developed only in a limited field, so there is a need to create a new space exploration payload. In foreign countries, there is a mass spectrometer as a basic equipment for space exploration, and it is a very useful payload that encompasses the exploration of life through the analysis of organic matter as well as the observation of the atmosphere and volatile substances of the exploration target. However, Korea has never developed a mass spectrometer payload for space exploration, so it is necessary to secure technology in preparation for future space exploration. Before that, we look at the scientific achievements of foreign mass spectrometer payloads for space exploration and identify trends.

• Journal of Industrial Convergence
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• v.20 no.12
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• pp.79-85
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• 2022

Recently, a smartphone manufactured on a flexible substrate has been released as an electronic device, and research on a stretchable electronic device is in progress. In this paper, a silicon-based stretchable material is made and used as a substrate to implement and evaluate an optical sensor device using oxide semiconductor. To this end, a substrate that stretches well at room temperature was made using a silicone-based solution rubber, and the elongation of 350% of the material was confirmed, and optical properties such as reflectivity, transmittance, and absorbance were measured. Next, since the surface of these materials is hydrophobic, oxygen-based plasma surface treatment was performed to clean the surface and change the surface to hydrophilicity. After depositing an AZO-based oxide film with vacuum equipment, an Ag electrode was formed using a cotton swab or a metal mast to complete the photosensor. The optoelectronic device analyzed the change in current according to the voltage when light was irradiated and when it was not, and the photocurrent caused by light was observed. In addition, the effect of the optical sensor according to the folding was additionally tested using a bending machine. In the future, we plan to intensively study folding (bending) and stretching optical devices by forming stretchable semiconductor materials and electrodes on stretchable substrates.

• Korean Chemical Engineering Research
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• v.61 no.1
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• pp.62-67
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• 2023

Due to the prolonged impact of COVID-19, the demand for Information Technology (IT) products is increasing, and their production facilities are expanded. Consequently, the use of harmful and dangerous chemicals are increased, the risk of fire(s) and explosion(s) is also elevated. In order to mitigate these risks, the government sets standards, such as KS C IEC 60079-10-1, and manages explosion-prone hazardous facilities where flammable substances are manufactured, used, and handled. However, using the standards of KS, it is difficult to predict the actual possibility of an explosion in a facility, because ventilation (an important factor) is not considered when setting up a hazardous work environment. In this study, the SEMI S6, Tracer Gas Test was applied to the chemical vapor deposition (CVD) facility, a major part of the display industry, to evaluate ventilation performance and to confirm the possibility of creating a less explosive environment. Based on the results, it was confirmed that the ventilation performance in the assumed scenarios met the standards stipulated in SEMI S6, along with supporting the possibility of creating a less explosive working condition. Therefore, it is recommended to use the prediction tool using engineering techniques, as well as KS standards, in such hazardous environments to prevent accidents and/or reduce economic burden following accidents.

• Journal of the Korean Geotechnical Society
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• v.24 no.6
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• pp.45-55
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• 2008

CFRD (Concrete Faced Rockfill Dam) has been world-widely constructed due to a lot of advantages which it has compared with rockfill dam and recently, sand/gravel materials, Instead of crushed rock materials, are also utilized as a main rockfill material to overcome geological and environmental problems. In Korea, two dams using sand/gravel materials as a main fill material were designed and are being constructed. In this research, the strength and deformation characteristics of the rockfill and sand/gravel materials taken from 2 dam sites were tested by using a laboratory large triaxial testing equipment for a total of 7 cases. From the results of large triaxial and compaction tests, it was observed that two kinds of materials show a little different compaction, shear strenght and deformation characteristics. It could be expected that the shear strength of sand/gravel material was not disadvantageous compared with that of rockfill materials, however, there was some difference between two materials with respect to behavior characteristics. On the other hand, smaller displacements were observed from numerical analysis based on the data from a large triaxial test when the sand/gravel is used as a main fill material compared with the case when the crushed rock material is used as a main fill material. Finally, in spite of a little different shear strength and behavior characteristic between two materials, it was concluded that it will not lead to a significant problem when the sand/gravel material is used as a main rockfill material.

• Journal of the Korean Society of Radiology
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• v.15 no.5
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• pp.697-704
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• 2021

It is hard to get Filaments which are materials of the 3D printing Fused Deposition Modeling(FDM) method as radiation shielding in Korea. and also related research is insufficient. This study aims to provide basic data for the development of radiation shields using 3D printing by evaluating the physical properties and radiation shielding capabilities of filaments containing metal particles. after selecting five metal filaments containing metal particle reinforcement materials, the radiation shielding rate was calculated according to the Korean Industrial Standard's protective equipment test method to evaluate physical properties such as tensile strength, density, X-ray Diffraction(XRD), and weight measurement using ASTM's evaluation method. In the tensile strength evaluation, PLA + SS was the highest, ABS + W was the lowest, and ABS + W is 3.13 g/cm³ which value was the highest among the composite filaments in the density evaluation. As a result of the XRD, it may be confirmed that the XRD peak pattern of the particles on the surface of the specimen coincides with the pattern of each particle reinforcing material powder metal, and thus it was confirmed that the printed specimen contained powder metal. The shielding effect for each 3D printed composite filament was found to have a high shielding rate in proportion to the effective atomic number and density in the order of ABS + W, ABS + Bi, PLA+SS, PLA + Cu, and PLA + Al. In this study, it was confirmed that the metal particle composite filament containing metal powder as a reinforcing material has radiation shielding ability, and the possibility of using a radiation shielding filament in the future.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.32 no.1
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• pp.1-6
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• 2022

In this research, a ring-shaped silicon carbide (SiC) single crystal manufactured using the PVT (Physical Vapor Transport) method was proposed to be applied to a SiC focus ring in semiconductor etching equipment. A cylindrical graphite structure was placed inside the graphite crucible to grow a ring-shaped SiC single crystal by the PVT method. SiC single crystal ring without crack was successfully obtained in case of using SiC single crystal wafer as a seed. A plasma etching process was performed to compare plasma resistance between the CVD-SiC focus ring and the PVT-SiC focus ring. The etch rate of ring materials in PVT-single crystal SiC focus ring was definitely lower than that of CVD-SiC focus ring, indicating better plasma resistance of PVT-SiC focus ring.

• Journal of Korean Society of Rural Planning
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• v.28 no.1
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• pp.1-15
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• 2022

A Care farm is known to have positive effects on various people in psychological, physical, and social aspects. However, care farm services for the disabled, transportation disadvantaged, and socially disadvantaged are limited. This study conducted a demand survey in order to provide basic data for development of the Agro-Healing Virtual Reality Therapy(AVRT) system. The respondents were the ordinary person(n=127) and the disabled person(n=72), and the survey items consisted of 4 categories and 20 items, including intention to use AVRT, requirements for use, factors to be considered when developing the system, and content and program preferences. The intention to use a AVRT was found to be at a high level of 80% or more by respondent characteristics. In addition, similar results were shown in all items such as virtual reality experience, willingness to use, appropriate use time, and willingness to pay by respondent characteristics, and correlation by item was determined through correlation analysis. As for the conditions of use, both sides preferred rural types and were found to have the purpose of healing. However, there were concerns about dizziness in common between system use, and in the case of the disabled person, there were difficulties in purchasing expensive equipment. In the development of the AVRT system, the part of sensory priority, important technology level, and color preference were evaluated, and the preference of content and programs to be developed in the system was identified. Fruit, vegetables, flowers, and animals preferred mandarin, tomato, tulips, and dogs first, horticultural healing preferred harvest management for the ordinary person, plant cultivation for the disabled person, and forest healing and animal education preferred walking and dog-related programs. However, agricultural work was found to be a program with high preference for making processed foods for the ordinary person and creating an animal breeding environment for the disabled person. The result of this study is expected to provide reference data that can be suggested for the development of Agro-healing Virtual Reality Therapy system.

• Korea Trade Review
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• v.43 no.3
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• pp.169-198
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• 2018

The purpose of this paper is to investigate the impact of exchange rate volatility on the export of Korean machinery intermediate goods to East Asian countries using the export demand model. In order to secure the validity of the estimation of the exchange rate volatility for the export of machinery intermediate goods, various methods of volatility measurement are used including the GARCH model, the moving average standard deviation and the 12-month fixed average standard deviation. The long-term relationship between variables was analyzed by applying the panel cointegration tests and DOLS & FMOLS panel estimations. Analysis results found that prior to the global financial crisis in 2008, the total exports of machinery and exchange rate volatility positively affect the exports of intermediate goods such as general machinery, electronic machinery and transportation equipment, but did not affect the exports of precision machinery intermediate goods. After the global financial crisis, however, exchange rate volatility negatively affected total exports and the exports of all machinery intermediate goods. When analyzing the period before and after the global financial crisis, it had a positive impact on exports of precision machinery intermediate goods and a negative effect on total exports and the exports of other machinery intermediate goods.

• Asia-pacific Journal of Multimedia Services Convergent with Art, Humanities, and Sociology
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• v.8 no.11
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• pp.109-119
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• 2018

This study investigates the effect of urban and architectural forms on the microclimate in urban areas. It applies urban and architectural elements such as urban form and tissue and building form and characteristics as the main influences on the microclimate within urban area. Among the 23 Automated Weather Stations (AWS) installed within Seoul city by the Korea Meteorological Administration, 6 sites were selected for the analysis, based on their different urban and architectural characteristics, and actual measurements were conducted in August 2017 using individual AWS equipment. Also, the measurements of microclimate and urban and architectural elements within a 500m radius of the AWS measurement points were collected and analyzed. The result of the analysis shows that the microclimate elements, such as wind speed, solar radiation, and temperature, were affected by the direction of the streets, the width, depth, and height of the buildings, the topographic elevation and direction and the traffic volume. This study is expected to contribute to mitigating urban heat island effect and setting the foundation for sustainable cities through development of urban management methods and techniques including the relationship between built environment elements and microclimate.