• Journal of the Microelectronics and Packaging Society
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• v.25 no.4
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• pp.9-15
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• 2018

This paper shows the principles and characteristics of the transient liquid phase (TLP) bonding technology for power modules packaging. The power module is semiconductor parts that change and manage power entering electronic devices, and demand is increasing due to the advent of the fourth industrial revolution. Higher operation temperatures and increasing current density are important for the performance of power modules. Conventional power modules using Si chip have reached the limit of theoretical performance development. In addition, their efficiency is reduced at high temperature because of the low properties of Si. Therefore, Si is changed to silicon carbide (SiC) and gallium nitride (GaN). Various methods of bonding have been studied, like Ag sintering and Sn-Au solder, to keep up with the development of chips, one of which is TLP bonding. TLP bonding has the advantages in price and junction temperature over other technologies. In this paper, TLP bonding using various materials and methods is introduced. In addition, new TLP technologies that are combined with other technologies such as metal powder mixing and ultrasonic technology are also reviewed.

• The Journal of Information Systems
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• v.31 no.2
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• pp.239-261
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• 2022

Purpose The purpose of this study is to explore and compare changes in tourist opinion during the COVID-19 pandemic. Since the COVID-19 outbreak has caused changes in all areas of our lives, the conditions related to confinement during a lockdown have led to changes in tourists' habits and behaviors. Design/methodology/approach To analyze opinion changes about tourist attractions, this study performed topic modeling by summarizing topics into five dimensions: management, scenery, price, suggestion, and safety; then, based on the topic modeling results, sentiment analysis and emotion analysis were conducted to explore the change of tourists' opinion during the COVID-19 pandemic. Findings According to the results, this study confirmed the pandemic's positive effect on tourists' opinions about attractions after the COVID 19 outbreak. Presumably due to the absence of lines and crowed. Moreover, the dimension 'Safety' started to appear in US tourists' attractions reviews only in the period after the outbreak and during the mass vaccination. These results mean that tourists started to care more about safety due to the impact of the COVID-19 pandemic.

• Korean Journal of Materials Research
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• v.32 no.10
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• pp.429-434
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• 2022

There is ongoing research to develop lithium ion batteries as sustainable energy sources. Because of safety problems, solid state batteries, where electrolytes are replaced with solids, are attracting attention. Sulfide electrolytes, with a high ion conductivity of 10^-3 S/cm or more, have the highest potential performance, but the price of the main materials is high. This study investigated lithium hydride materials, which offer economic advantages and low density. To analyze the change in ion conductivity in polymer electrolyte composites, PVDF, a representative polymer substance was used at a certain mass ratio. XRD, SEM, and BET were performed for metallurgical analyses of the materials, and ion conductivity was calculated through the EIS method. In addition, thermal conductivity was measured to analyze thermal stability, which is a major parameter of lithium ion batteries. As a result, the ion conductivity of LiH was found to be 10^-6 S/cm, and the ion conductivity further decreased as the PVDF ratio increased when the composite was formed.

• Journal of Korean Society of Rural Planning
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• v.28 no.4
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• pp.31-39
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• 2022

This study empirically analyzed the welfare effect of the military purveyance program, which plays an important role in maintaining the sales channel and demand base in Korea's agricultural and livestock industry, as well as the stable supply of safe ingredients for military meals essential for the morale and combat power of soldiers. The military purveyance program causes additional demand for domestic livestock products, affecting the trading volumes and price levels in the market. This will change the welfare of producers and consumers, and affect the welfare of soldiers who are subject to military meals. The analysis results obtained through a simulation method based on the equilibrium displacement model are as follows. In the case of pork delivered for military service, producer surplus increased by KRW 55.3-62.2 billion and consumer surplus decreased by KRW 55.1~62.0 billion based on pork production in 2021. It wad analyzed that the consumer surplus in the military supply market, rather than the conventional market, increased by KRW 96.9 billion won, resulting in a total welfare gain of KRW 97.1 billion.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.26 no.2
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• pp.321-324
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• 2022

The Korean halibut farming industry suffer from price instability and demand decrease due to various environmental and social issues. It is urgent to predict the appropriate amount of halibut production. However, it is not easy for employments working in the halibut farming industry to handle statistical tools in order to perform the prediction. In this paper, we implemented a Excel-based regression analysis tool that allows users to get a regression analysis result by just entering historical data in a sheet. Our tool will reduce workloads of employments working in the halibut farming industry by enabling them to perform a regression analysis with Excel on-the-fly. This study expect that by using the tool the halibut farming industry cope actively with the real-time change in the industry.

• Korean Journal of Agricultural Science
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• v.48 no.4
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• pp.739-751
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• 2021

The thawing process is usually essential for imported pork because this product is typically distributed frozen. Consumers prefer fresh pork because discoloration, nutrient spills, and microbial contamination are high during the thawing process. The illegal act of selling frozen pork by disguising it as fresh pork through various methods can occur for the benefit of the difference in the sales price. However, there is some difficulty in securing systematic and objective data, as sensory tests are generally performed on imported pork. In the experiment conducted here, the electrical conductivity and dielectric properties of pork neck and pork belly products were measured. The amounts of change before and after freezing were compared through a statistical analysis, and a new method for determining frozen meat was proposed based on the analysis results. The weight was reduced compared to that before freezing due to the outflow of drips from the thawing process, but there was no difference in the drip loss level due to the thawing method. Vacuum packaging was found to lead to more drip loss than regular packaging, but the difference was not statistically significant. Frozen pork neck meat can be determined by measuring the electrical conductivity in the lean parts and the dielectric characteristic in the fatty parts. Frozen pork belly is determined by measuring the dielectric constant of the part closest to the outer fat layer.

• Current Photovoltaic Research
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• v.10 no.1
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• pp.6-15
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• 2022

Climate change is among the most important issues facing mankind in modern society. However, global PV energy expansion has been driven mainly by OECD countries. We investigate the determinants of PV energy growth by panel data of selected OECD countries from 1991 to 2018. We investigate four categories of driving factors: socioeconomic, technological, country specific, and policy factors. The test results support that PV capacity growth is significantly driven by technology development and multidimensional environment policy factors. Socioeconomic factors such as CO₂, GDP, and electricity price are statistically significant on the growth of PV energy, too. Whereas, country-specific solar potential factor is the least related. As most of the socioeconomic factors are exogenous, we need to focus more on PV technology development and policy measures.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2020.06a
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• pp.48-49
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• 2020

Recently the diversification of construction market and the continuous reduction of construction amount are raising the need of alternative delivery method in the construction industry. The foreign advanced companies actively adopted the CM at Risk delivery method where they perform the service of agent CM in the design phase, and agree GMP(Guaranteed Maximum Price) with the client at the time of 50~80% completion of design. Even in Korea they began to apply that method to pilot projects. In CM at Risk, through the early participation of builder, the level of design completion can be improved and the change order and construction period delay can be minimized. On the other hand, GMP is usually calculated when the design is about 80% complete, so there is uncertainty in the construction cost. Therefore, in this research, the increased amounts of construction cost are analyzed in a number of public construction projects, and GMP calculation process is proposed using the analysis results and CBR(Case-Based Reasoning) technique to reduce the construction cost increase in the construction phase.

• SUVANNABHUMI
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• v.15 no.1
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• pp.255-275
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• 2023

Trade between South Korea and Malaysia has been steadily increasing since the conclusion of the multilateral Free Trade Agreement (FTA) between the Association of Southeast Asian Nations (ASEAN) and South Korea. Bilateral FTAs such as Singapore-South Korea, Vietnam-South Korea, and Indonesia-South Korea came into effect to enhance the economic cooperation between South Korea and major ASEAN countries. However, the bilateral FTA between South Korea and Malaysia, known as Republic of Korea-Malaysia FTA, is still under negotiation. Therefore, this study aims to analyze the economic impact of a possible FTA between these two countries. To examine the economic effects of bilateral FTAs, this study analyzes the trade structure and change in the value of trade between Malaysia and South Korea using panel data analysis. Two significant findings were identified by the analysis. First, the Republic of Korea-Malaysia FTA is expected to promote trade and have a positive effect on the Gross Domestic Product (GDP) of South Korea. Second, the result of the calculated price elasticity based on substituting figures such as tariff, demand elasticity, and export value is that the value of manufacturing exports is expected to considerably get an increase. Therefore, an early FTA between South Korea and Malaysia would be beneficial for both national economies.

• International conference on construction engineering and project management
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• 2013.01a
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• pp.386-389
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• 2013

Under climate change and urbanization, rainwater harvesting (RWH) systems are emerging as an alternative source of water supply because of growing concern about water sustainability. RWH systems can satisfy the various watering needs and provide the environmental benefits of lessening the damages from flood, drought, and runoff. The economic success of a RWH system is vitally concerned with the determination of the design capacity of storage tank to be built in the system. The design capacity is determined by the factors of average annual rainfall, period of water scarcity, and water price during the whole life-cycles. Despite the high uncertainties inherent in these factors, the current engineering design of RWH system construction often assumes that storage tanks should be built all at once. This assumption implicitly ignores the managerial flexibility in responds to the future as new information comes out-the right to build storage tanks stage by stage depending on the evolution of demand. This study evaluates the value of a multistage storage tank construction using a real option approach. A case study involving a typical RWH system construction in Jeonju, the Republic of Korea is conducted. The managerial flexibility obtained from the real option perspective allows engineers to develop investment strategies to better cope with the issue of water sustainability.