• Korean Chemical Engineering Research
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• v.58 no.2
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• pp.209-223
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• 2020

Executions of SCM in a chemical company of which divisions produce petrochemicals, compounds, batteries, IT material and medicine directly affect their own profit. Execution level of SCM or optimization is very important. This work presents activities of SCM and optimization of inefficient issues in several industrial divisions using mathematical optimization method. The meaning is not only academic research but also making a useful tool which active partner deals with in his work. It is explained how to do beforehand and afterward optimization problem. The benefits are mentioned in the sections. The first of examples would be cover supply plan optimization, optimal profit business plan, and scheduling of a stretching process of polarizer based on minimizing raw material loss in polarizer production. The second example would be cover the optimization of production/packaging plans to maximize productivity of Poly Olefin processes, and the third example is minimization of transition loss in the production of battery electrodes. The fourth example would be cover scheduling of vessel approaching to berth. Because transportation of large portion of raw material and products of petrochemical industry is dealt with vessel, scheduling of vessel approaching to berth is important at the shore of large difference of tide. The final example would be scheduling problem to minimization of change over time of ABS semi products.

• Resources Recycling
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• v.30 no.1
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• pp.44-52
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• 2021

This study investigated the effect of the type of alkaline precipitant used on the synthesis of lithium hydroxide by examining the behavior of lithium hydroxide produced using lithium sulfate recovered from a waste lithium secondary battery as a raw material. The double-replacement reaction (DRR) process was used to remove the impurities contained in the lithium salt precursor of lithium sulfate and to improve the efficiency of the synthesis of lithium hydroxide. The experiment was conducted by control the molar ratio of the precursor ([Li]/[OH]), the reaction temperature, and the composition of the alkaline precipitant (KOH, Ca(OH)2, Ba(OH)2) used for the production of highly-crystalline lithium hydroxide. A secondary solid-liquid separation was performed following the reaction to remove the impurities generated, and the purified aqueous solution of lithium hydroxide was evaporated to remove the moisture and obtain the product as a powder. The crystallinity and synthesis behavior of the product were examined.

• Journal of the Korean Institute of Landscape Architecture
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• v.51 no.5
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• pp.1-12
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• 2023

This study evaluated the overturning stability of portable tripod ladders used for high-altitude work such as tree management and pruning work in landscaping construction and management. Portable tripod ladders, which are included in general mobile or portable ladders frequently used in industrial sites, are supported in a triangular support structure, not a 4-point support like common A-type Ladders. In addition, since the working height is more than twice that of a mobile or portable ladder, the possibility of an overturning accident that threatens the safety of workers with a fall accident is high. Therefore, based on the overturning stability test specified in ANSI-ASC A14.7 and EN 131-Part 7, which are related standards for about 130 types of portable tripod ladders sold and used in Korea. An equation to calculate each moment according to working height was derived. Then, each calculated moment was compared to evaluate the safety factor for overturning and stability. As a result of the overturning stability evaluation according to each standard, when the provisions of EN 131-Part 7 were applied, portable tripod ladders with 8 steps in the rear direction and 6 steps or more in the side direction were evaluated as unstable against overturning, but according to ANSI-ASC A14.7 regulations. It was evaluated that the stability against overturning was secured in all directions and number of steps.

• Journal of Powder Materials
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• v.31 no.2
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• pp.169-179
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• 2024

Colloidal quantum dot (QDs) have emerged as a crucial building block for LEDs due to their size-tunable emission wavelength, narrow spectral line width, and high quantum efficiency. Tremendous efforts have been dedicated to improving the performance of quantum dot light-emitting diodes (QLEDs) in the past decade, primarily focusing on optimization of device architectures and synthetic procedures for high quality QDs. However, despite these efforts, the commercialization of QLEDs has yet to be realized due to the absence of suitable large-scale patterning technologies for high-resolution devices., This review will focus on the development trends associated with transfer printing, photolithography, and inkjet printing, and aims to provide a brief overview of the fabricated QLED devices. The advancement of various quantum dot patterning methods will lead to the development of not only QLED devices but also solar cells, quantum communication, and quantum computers.

• Journal of Energy Engineering
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• v.23 no.1
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• pp.21-32
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• 2014

This study has analyzed whether the virtuous cycle of value-added between the processes within the company has formed and whether the virtuous ecosystem between the processes within the industry has been built through the analysis of value chain(VC) and value system(VS) targeting the Korean photovoltaic companies. For a study method, after conducting a survey on the companies, a regression analysis was performed on the causal relationship between the process within the VC and VS. Based on the results of the analysis, for the VC of the Korean photovoltaic industry, an increase in the R&D support from the government has led to the increase in the investment of R&D for the related industry, and the increase in the investment of R&D has contributed to the increase in the growth of its productivity, and the growth in the productivity of R&D has influenced the increase in the production of solar products. In addition, the reduction of photovoltaic production cost for the company has influenced the increase of recurring profit margin compared to the sales. However it was shown that the increase in the company's production volume does not contribute to the reduction of production cost. Meanwhile, the increase in recurring profit margin compared to the sales were influencing the increase in the production volume but it was shown that the increase in the company's investment of R&D was not a contributing factor thus it was not included in the virtuous cycle. It was analyzed that the VS was shown not to influence all other processes within the industry except for the module companies where the increase in the recurring profit margin compared to the sales was influenced by the increase in the recurring profit margin compared to the sales of solar cell companies. This shows that the virtuous industrial ecosystem which should be made under the mutual cooperation by the ingot, wafer, solar cell, module and system companies are yet incomplete.

• Proceedings of the Korean Vacuum Society Conference
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• 2012.02a
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• pp.202-202
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• 2012

유연성 투명 전도막은 현대 전자산업의 발전에 있어 필수적인 부품소재로서, 가시광선의 투과율이 80% 이상이고 면저항이 $100{\Omega}/sq.$ 전후이며 휘거나 접히고 나아가 두루마리의 형태로도 응용이 가능한 소재를 일컫는다. 이러한 유연성 투명 전도막은 차세대 정보디스플레이 산업 및 유비쿼터스 사회의 중심이 되는 유연성 디스플레이, 터치패널, 발광다이오드, 태양전지 등 매우 다양한 분야에 응용이 기대된다. 이러한 이유로 고 신뢰성 유연성 투명 전도막 개발기술은 차세대 산업에 있어서의 핵심기술로 인식되고 있다. 현재로서는 인듐 주석 산화물(indium tin oxide; ITO) 및 전도성 유기고분자를 사용하여 투명 전도막을 제조하고 있으나, ITO 박막의 경우 인듐 자원의 고갈로 인한 가격상승 및 기판과의 낮은 접착력, 열팽창계수의 차이로 인한 공정상의 문제, 산화물 특유의 취성으로 인한 유연소자로서의 내구성 저하 등의 문제가 제기되고 있다. 전도성 유기고분자의 경우는 낮은 전기전도도와 기계적강도, 유기용매 처리 등의 문제점이 지적되고 있다. 따라서 높은 전기전도도와 투광도 뿐만 아니라 유연성을 지니는 재료의 개발이 요구되고 있는 실정이다. 최근 이러한 재료로서 그래핀(graphene)과 탄소나노튜브(carbon nanotube; CNT)를 중심으로 하는 탄소나노재료가 주목받고 있으며 많은 연구가 활발히 진행되고 있다. 본 연구에서는 열화학기상증착법(thermal vapor deposition; TCVD)으로 합성된 그래핀 및 CNT를 이용하여 탄소나노재료 복합체 기반의 유연성 투명 전도막을 제작하고 그 특성을 평가하였다. 그래핀과 CNT합성을 위한 기판으로는 각각 300 nm 두께의 니켈과 1 nm 철이 증착된 실리콘 웨이퍼를 이용하였으며, 원료가스로는 메탄(CH4)과 아세틸렌(C2H2)등의 탄화수소가스를 이용하였다. 그래핀의 경우 원료가스의 유량, 합성온도, 냉각속도를 변경하여 대면적으로 두께균일도가 높은 그래핀을 합성하였으며, CNT의 경우 합성시간을 변수로 길이 제어합성을 도모하였다. 합성된 그래핀은 식각공정을, CNT는 스프레이 증착공정을 통해 고분자 기판(polyethylene terephthalate; PET) 위에 순차적으로 전사 및 증착하여 탄소나노재료 복합체 기반의 유연성 투명 전도막을 제작하였다. 제작된 탄소나노재료 복합체 기반의 유연성 투명 전도막은 물리적 과부하를 받았을 때 발생할 수 있는 유연성 투명 전도막의 구조적결함에 기인하는 전도성 저하를 보상하는 특징이 있어, 그래핀과 탄소나노튜브 각각으로 제조된 유연성 투명 전도막보다 물리적인 하중이 반복적으로 인가되었을 때 내구성이 향상되는 효과가 있다. 40% 스트레인을 반복적으로 인가하였을 때 그래핀 투명 전도막은 20 사이클 이후에 면저항이 $1-2{\Omega}/sq.$에서 $15{\Omega}/sq.$ 이상으로 급증한 반면 그래핀-CNT 복합체 투명 전도막은 30사이클까지 $1-2{\Omega}/sq.$ 정도의 면저항을 유지하였다.

• Journal of Climate Change Research
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• v.4 no.3
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• pp.221-233
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• 2013

Due to the fact that the speed of climate change in Republic of Korea exceeds the global average speed, sound conservation and tourism strategies should be prepared based on the comparison between the meteorological factors and the number of tourists. In this context, almost 70 percent of the industries in Ulleung-do are closely related to tourism; hence the significance of tourism is increasing. The annual precipitation variation does not show remarkable fluctuation, and most precipitation has a tendency to fall in summer and autumn However, for the years 2010 and 2011, a different trend was exhibited with higher winter precipitation than any other periods. Precipitation intensity is usually stronger in May (in the morning), June (in the afternoon), and no big difference is shown between morning and afternoon precipitation from July to September. The number of tourist is compared to both the precipitation at Ulleung-do and the number of advisories and warnings in the East Sea of Korea using correlation analysis. The results demonstrate that the meteorological factors that reduce the number of tourist are precipitation and the number of advisories and warnings.

• Resources Recycling
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• v.32 no.6
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• pp.67-78
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• 2023

The rare metals used as raw materials in high-tech industries undergo changes in demand structures and supply chains following domestic industrial structural shifts and technological advancements, exhibiting high price volatility. Therefore, it is necessary to periodically analyze changes in the demand structures of rare metals. Since domestic demand for most rare metals relies on imports in Korea, the changes in domestic demand for rare metals can be identified by analyzing changes in their trade structure. In the present study, we analyze the changes in trade volume, trade growth rate, trade rankings, and trading countries from 2000 to 2022 for 35 rare metals, categorized into five types-ores, metals, alloys, compounds, and scrap. The trade of the raw materials of rare metals in Korea has generally increased since the 2000s, except for a significant decline in 2009 and 2016. The total trade volume, encompassing both exports and imports, has increased by approximately tenfold in 2022 compared to 2001. Until the mid-2010s, the trade of the raw materials of rare metals was primarily focused on those used in steel-manufacturing such as silicon, nickel, chrome, molybdenum, manganese, and others. However, after that period, there has been an increase in the trade of platinum group metals like palladium, rhodium, platinum, and the raw materials of rare metals for secondary battery-manufacturing such as lithium and cobalt. Particularly in 2022, lithium has become the largest share in trade of the raw materials of rare metals in Korea, due to the price surge and increase in demand.

• Journal of Korea Society of Industrial Information Systems
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• v.24 no.5
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• pp.9-16
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• 2019

In today's global energy market, the importance of green energy is emerging. Hydrogen energy is the future clean energy source and one of the pollution-free energy sources. In particular, the fuel cell method using hydrogen enhances the flexibility of renewable energy and enables energy storage and conversion for a long time. Therefore, it is considered to be a solution that can solve environmental problems caused by the use of fossil resources and energy problems caused by exhaustion of resources simultaneously. The purpose of this study is to efficiently produce hydrogen using plasma, and to study the optimization of DME reforming by checking the reforming reaction and yield according to temperature. The research method uses a 2.45 GHz electromagnetic plasma torch to produce hydrogen by reforming DME(Di Methyl Ether), a clean fuel. Gasification analysis was performed under low temperature conditions ($T3=1100^{\circ}C$), low temperature peroxygen conditions ($T3=1100^{\circ}C$), and high temperature conditions ($T3=1376^{\circ}C$). The low temperature gasification analysis showed that methane is generated due to unstable reforming reaction near $1100^{\circ}C$. The low temperature peroxygen gasification analysis showed less hydrogen but more carbon dioxide than the low temperature gasification analysis. Gasification analysis at high temperature indicated that methane was generated from about $1150^{\circ}C$, but it was not generated above $1200^{\circ}C$. In conclusion, the higher the temperature during the reforming reaction, the higher the proportion of hydrogen, but the higher the proportion of CO. However, it was confirmed that the problem of heat loss and reforming occurred due to the structural problem of the gasifier. In future developments, there is a need to reduce incomplete combustion by improving gasifiers to obtain high yields of hydrogen and to reduce the generation of gases such as carbon monoxide and methane. The optimization plan to produce hydrogen by steam plasma reforming of DME proposed in this study is expected to make a meaningful contribution to producing eco-friendly and renewable energy in the future.

• Journal of fish pathology
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• v.35 no.1
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• pp.1-25
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• 2022

The aquaculture industry has developed rapidly over the last three decades and is an important industry that supplies over 15% of humans' animal protein intake; therefore, there is a need to increase production to meet the continuous demand. The fish cage farms on the southern coast (Kyengsangnam-do and Jeollanam-do) of Korea are critical resources in aquaculture because they account for approximately 90% of the national total fish cage farms by water area ratio. However, the current aquaculture environment is being gradually affected by climate change, which is a global issue, and its effects are expected to intensify in the future. Therefore, it is urgently imperative to accurately evaluate the effects of climate change on South Korean aquaculture industries and to develop social and national strategies to minimize damage to the fishing industry. The damage to fish farmed in cage farms on the southern coast is increasing annually and the leading causes are high and low water temperature and red tides, which are directly or indirectly related to climate change. At present, global warming can provide opportunities for aquaculture industrialization of fish or other novel species, with economic implications. However, despite such opportunities, the influx of new species can also cause problems such as ecological disturbances, increase in the reproduction frequency of microalgae such as red tide, increase in disease incidence, and occurrence and periods of high water temperatures in summer. The scale of farmed fish mortality is increasing due to the complex effects of these factors. Increased damages due to fish mortality not only have severe economic impacts on the aquaculture industry, but the social costs of responding to the damage and follow-up measures also increase. various active responses can reduce the mortality damage in fish farms such as improving the management skills in aquaculture, improved species breeding, efficient food management, disease prevention, proactive responses, and system-wide improvements. This review article analyzes the large-scale mortality cases occurring in fish cage farms on the southern coast of Korea and proposes measures to mitigate mortality and enhance responses to such scenarios.