• Journal of the Korea Institute of Building Construction
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• v.23 no.2
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• pp.175-185
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• 2023

Upon analyzing labor productivity in the construction industry across OECD countries, it was found that in 2019, labor productivity per employee in the South Korean construction industry was lower than that of major developed countries when adjusted for purchasing power parity(PPP). Specifically, when benchmarked against other countries at a base of 100, South Korea scored 76.9 in the United States, 88.4 in Japan, and 85.1 in the OECD average. Notably, South Korea ranked 25th in labor productivity per employee in the construction industry among 35 OECD countries in 2019, indicating a low standing. A comparative analysis of the construction market size and labor productivity in the construction industry across OECD countries revealed that larger construction markets did not necessarily correlate with higher labor productivity. To enhance labor productivity in the construction industry, this study proposed the active implementation of smart construction technology at construction sites and the promotion of on-site assembly work using off-site construction(OSC) technology, rather than traditional on-site labor. Moreover, it was recommended that the development of modular construction methods and technologies be expanded. In the future, if off-site production methods and modules are further developed through advanced robotics and factory automation, labor productivity is anticipated to increase due to the restructuring of production methods, such as manufacturing.

• Journal of the Korean Recycled Construction Resources Institute
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• v.11 no.1
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• pp.55-61
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• 2023

This study aims to develop CLSM fill material for emergency restoration using landfill coal ash. As a result of examining physical properties such as particle size distribution and fines content of landfill coal ash, bottom ash, fly ash, and general soil were mixed, and SP was found to have a density of 2.03 and a residual particle pass rate of 7.8 %. CLSM materials that secure fluidity in unit quantities without using chemical admixtures such as glidants and water reducing agents have a high risk of material separation due to bleeding. As a result of this experiment, it was found that the bleeding ratio did not satisfy the standard in the case of the specimen with a large amount of fly ash and a lot of addition of mixing water. As a result of the compressive strength test, the strength development of 0.5 MPa or more for 4 hours was found to be satisfactory for the specimens using hemihydrate gypsum with a unit binder amount of 200 or more, and the remaining gypsum showed poor strength development. Although it is judged that landfill coal ash can be used as a CLSM material, it is necessary to identify and apply the physical and chemical characteristics of coal ash buried in the ash treatment plant of each power generation company.

• Asia-pacific Journal of Multimedia Services Convergent with Art, Humanities, and Sociology
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• v.5 no.3
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• pp.291-299
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• 2015

With recent surge of attention to heating and air conditioning energy consumption, the need for evaluating performance of heating and air conditioning energy is also on the rise. This research aims to propose daily-life based evaluation method as an alternative to existing one, as well as to apply the method in real life to prove its validity. The results are as following. 1) I studied temperatures preferred by persons indoors and appropriate level of temperature, and the results show that properties of such persons such as age is directly linked with pleasantness of the room, but the issue lies with the fact that such properties are not considered in existing performance evaluation of heating and air conditioning. 2) Daily life based evaluation proposed herein reflects such properties of persons indoors. It controls heating / air conditioning devices installed in the test bed with the same size as a real life room to get quantitative and visual performances in our daily life as well as simple temperature information. 3) To verify validity of daily life based evaluation, I conducted different evaluation sessions with and without a blind and also based on ages of persons indoors. Results based on properties of persons showed difference of 77.6%, leading to effective analysis of energy consumption pattern by heating / air conditioning devices. This research takes significance in that it comes with a new performance evaluation method based on real life, and I gather that further studies are required to develop more multilateral performance evaluation in order to verify and improve technology for reduction of energy consumption.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.33 no.2
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• pp.103-114
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• 2023

Objectives: This study was conducted to evaluate hand-arm vibration (HAV) exposure levels due to the use of power hand tools and to evaluate the determinants in the automobile assembly process. Methods: The exposure level to HAV was evaluated for 30 work lines in five assembly processes (body, engine, chassis, door, and design) that use air-powered tools and battery-powered tools and operate in circulation for two hours. The 2-hr equivalent energy vibration acceleration, A (2), of the task was measured. The 8-hr equivalent energy vibration acceleration, A (8), was estimated in consideration of the number of tasks that can be performed per day by each process. In addition, a survey on the working environment was conducted with workers exposed to vibration. Results: The geometric mean of the HAV exposure level, A (2), for a total of 30 tasks was 2.51 m/s², and one case was 10.30 m/s², exceeding TLV (2hr). The HAV exposure level of A (8) was evaluated from 1.03 m/s² to 5.36 m/s². A (2) showed a statistically significant difference (P<0.01) for each process, and the chassis process (GM=3.90 m/s²) was the highest. The larger the tool size and the longer the tool length, the higher was the vibration acceleration when using a battery-powered tool than an air-powered tool (P<0.01). Battery-powered tool users showed higher dissatisfaction on all items than did air-powered tool users. Conclusions: As a result of this study, it is necessary to implement a program to reduce the HAV exposure levels.

• 한국노년학
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• v.29 no.2
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• pp.489-511
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• 2009

While late-life suicide has been increasing and become an important issue for public health in Korea, little is known about the phenomenon and its contributing risk factors based on which effective preventive measures can be made. Since suicidal ideation is a major precursor to attempted and completed suicide, the objective of the present study was to reveal primary contributors to suicidal ideation. Data were collected from a cross-sectional survey of 247 community-dwelling Korean older adults (age≥60) in the mid-size city in Korea. The statistical methodology employed a robust hierarchical regression procedure that iteratively downweights outliers. Based on the stress-diathesis model, the study examined major diathesis and stressors directly explaining suicidal ideation. The study also explored the significant interaction among these factors. The findings revealed that living alone and depression were significant main antecedents of suicidal ideation. In addition, neuroticism X life events and neuroticism X depression were significant interaction terms with the strongest explanatory power, which provides an empirical evidence to support the stress-diathesis model in explaining suicidal phenomenon of the Korean elderly. The result demonstrates the theoretical implication as well as the practical implication for developing and implementing late-life suicide prevention strategies. Limitations and directions for future research are discussed.

• Korean Journal of Culture and Social Issue
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• v.17 no.3
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• pp.261-285
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• 2011

In our studies, We defined the concept of social reputation and aimed to estimate the effect of social reputation on likability, trust, preference of interpersonal relationship. To accomplish these goal, photographs of 12 persons(six young unmarried man, six young unmarried women) volunteered were shown to 60 raters, and the one male and one female pictures of scores of facial attractiveness are nearest to median were selected as experimental figures in preliminary study. After this, We asked 260 raters to assess likability, trust, preference of interpersonal relationship after showing raters the chosen pictures of man and woman and telling scenario of positive, negative reputation about these two persons. The outcomes showed that in both men and women, likability, trust, preference of persons who gained positive reputation were significantly higher than persons gained negative reputation. Facial attractiveness was effect on likability, trust, and preference, but effect size of reputation was much higher on likability, interpersonal preference, especially trust level. Also, in three-way ANCOVA results, Woman has showed higher likability and trust than man under the condition of good reputation in both woman was rater and object to be assessed, but on the contrary, likability, trust, and preference of woman were lower than man in either woman was rater or object to be judged under the bad reputation,. Lastly, this study's implications and limitations were discussed.

• Korea Trade Review
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• v.48 no.2
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• pp.111-127
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• 2023

While the e-commerce market in Southeast Asia is growing, this study aims to derive factors for establishing an entry strategy for the Cambodian e-commerce market where Korean logistics companies can strategically enter in the future. Cambodia is a country where growth and growth potential in the e-commerce market is steadily increasing based on the high youth population ratio, high smartphone penetration rate, the introduction of convenient payment systems, and government-level e-commerce promotion policies. In this study, Korean logistics companies established detailed promotion strategies by deriving factors necessary for Cambodia's entry into the e-commerce market and analyzing their relative importance. The AHP analysis technique derived three top factors for the entry strategy, and each presented four sub-factors. As a result, the importance was shown in the order of 'Market Factor' (0.556), 'Policy and Institutional Factor' (0.295), and 'Corporate Competency Factor' (0.149). As a result of the sub-factors analysis, the importance was found in the order of "Characteristics and Growth Potential of Distribution Channel" (0.230), "Purchasing Power and Awareness Level of Consumers" (0.176), "Cambodia Government's E-commerce Policy and Institutional Support" (0.122), and "Cambodia Government's Logistics Infrastructure Plan" (0.108). In both the upper and lower factors, the characteristics and growth potential of the Cambodian e-commerce market were important, indicating that Korean logistics companies value market size and growth potential to enter the Cambodian e-commerce market. The results of this study can be used as a guideline to help Korean logistics companies make successful inroads into Cambodia, where the e-commerce market is expected to grow in the future.

• Journal of the Microelectronics and Packaging Society
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• v.30 no.4
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• pp.8-16
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• 2023

The importance of next-generation packaging technologies is being emphasized as a solution as the miniaturization of devices reaches its limits. To address the bottleneck issue, there is an increasing need for 2.5D and 3D interconnect pitches. This aims to minimize signal delays while meeting requirements such as small size, low power consumption, and a high number of I/Os. Hybrid bonding technology is gaining attention as an alternative to conventional solder bumps due to their limitations such as miniaturization constraints and reliability issues in high-temperature processes. Recently, there has been active research conducted on SiCN to address and enhance the limitations of the Cu/SiO₂ structure. This paper introduces the advantages of Cu/SiCN over the Cu/SiO₂ structure, taking into account various deposition conditions including precursor, deposition temperature, and substrate temperature. Additionally, it provides insights into the core mechanisms of SiCN, such as the role of Dangling bonds and OH groups, and the effects of plasma surface treatment, which explain the differences from SiO₂. Through this discussion, we aim to ultimately present the achievable advantages of applying the Cu/SiCN hybrid bonding structure.

• Korean Journal of Organic Agriculture
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• v.31 no.4
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• pp.413-426
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• 2023

These experiments were conducted for 3 years from 2021 to 2023 to develop a method that can be safely used to prevent the leakage of Golden apple snails (Pomacea canaliculata) from eco-friendly rice plantations. In the southern part of Jeollanam-do, after planting rice, the young golden apple snails placed in the rice field become adults around mid-July and begin spawning. These individuals can overwinter in drains that do not dry out, but individuals hatched after mid-July will not mature enough to overwinter. The size of golden apple snails overwintered in the drainage canal was more than 2.5cm in shell height. Installing a net at the inlet could block 95% of the inflow of snails, and 99% of outflow was blocked by installing an improved water trap and net at the drain. During the mid-drying period and pre-harvest drying period, a water path was created with a power paddy pottery machine. 59.5% of snails were attracted to the waterway, and it took 130 minutes to build the waterway and collect the snails. Based on these results, seasonal paddy management tips for the safe use of giant snails in rice fields were suggested.

• Explosives and Blasting
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• v.41 no.3
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• pp.62-72
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• 2023

The aging of plant structures due to industrialization in the 1970s has increased the demand for blast demolition. While blasting can reduce exposure to environmental pollution by shortening the demolition period, improper blasting design and construction plans pose significant safety risks. Thus, it is vital to consider optimal blasting demolition conditions and other factors through collapse behavior simulation. This study utilizes a 3-D combined finite-discrete element method (FDEM) code-based 3-D DFPA to simulate the collapse of a chimney structure in a thermal power plant in Seocheon, South Korea. The collapse behavior from the numerical simulation is compared to the actual structure collapse, and the numerical simulation result presents good agreement with the actual building demolition. Additionally, various numerical simulations have been conducted on the chimney models to analyze the impact of the duct size in the pre-weakening area. The no-duct, duct, and double-area duct models were compared in terms of crack pattern and history of Z-axis displacement. The findings show that the elapse-time for demolition decreases as the area of the duct increases, causing collapse to occur quickly by increasing the load-bearing area.