• Bulletin of the Korea Photovoltaic Society
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• v.6 no.2
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• pp.34-41
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• 2020

최근 주요 기업들을 대상으로 전력 사용을 100% 재생에너지로 전환하자는 RE100 캠페인이 국내외에서 뜨거운 관심을 받고 있다. 2019년 12월 기준으로는 Apple, BMW Group 등 전 세계 211개 기업이 RE100 캠페인에 참여한 것으로 알려져 있다. RE100이 확산됨에 따라 해외 RE100 기업이 국내 협력기업에게도 재생에너지 사용을 요청하는 사례가 발생하고 있는데, 국내는 RE100 도입을 위한 전력거래제도가 마련되지 않았고, 재생에너지 발전원가가 높아 당장의 RE100 이행은 어려운 상황이다. 이에 따라, 장차 RE100이 국내 기업에 무역장벽으로 작용할 가능성이 제기되고 있어 본고에서는 RE100의 현황과 RE100 도입 비용을 낮추는 방안으로써 RE100과 탄소배출권의 연계에 대해 논의하고자 한다. 이를 통해 탄소배출권과 연계한 RE100 이행이 가능해지는 경우, 국내 재생에너지 보급 확대 및 국가 탄소배출 감축 계획 이행에 기여할 수 있을 것으로 예상된다.

• Current Photovoltaic Research
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• v.10 no.2
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• pp.62-71
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• 2022

The Global RE100 campaign is a one of the voluntary campaign, but it has a lot of influence on domestic companies that have not yet joined the Global RE100. Accordingly, the Korean government introduced the Korean RE100 (K-RE100) system to prepare an institutional mechanism for domestic companies to respond to RE100. However, in Korea, due to the high LCOE of renewable energy and institutional limitations of the power transaction system, there is a limit for companies to implement RE100 in various ways. Therefore, in this study, the implementation cost of RE100 for green tariff, REC purchase, third-party PPA, direct(or corporate) PPA, and self-generation was compared and analyzed to derive the order of implementation with the net present value (NPV) of costs incurred over 20 years. As a result, self-construction was analyzed as the most economical method, but the implementation through the green tariff seemed to be the most realistic implementation method so far. However, considering the gradually falling LCOE, third-party PPA and direct PPA could be secured competitiveness against green tariff in 2025 and 2026. Then it could allow the companies to have various portfolios for implementation of RE100.

• Journal of the Korean Society of Food Science and Nutrition
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• v.42 no.12
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• pp.1949-1957
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• 2013

The contents of ${\beta}$-carotene and retinol in processed and restaurant foods, such as Korean noodles, mandus, rice cakes and bread products, were quantified by high-performance liquid chromatography (HPLC) with UV/visible and fluorescence detector, respectively. Samples were collected from different local areas (i.e. Gangwon-do, Gyeonggi-do, Gyeongsang-do, Seoul, Jeolla-do, and Chungcheong-do). After homogenization, samples were hydrolyzed by direct alkali saponification; thereafter, fat-soluble components were extracted by a mixture of n-hexane/ethylacetate (85:15, v/v), containing 0.01% butylated hydroxytoluene (BHT). ${\beta}$-carotene and retinol contents in infant formula used as an in-house material for the analytical quality control. Among 14 Korean noodles, high contents of ${\beta}$-carotene were found in Bibim-Guksu (average 442.43 ${\mu}g/100g$) and Jjolmyeon (average 301.39 ${\mu}g/100g$). In 4 Korean mandus, the highest contents of ${\beta}$-carotene was determined in Kimchi-mandu (average 197.64 ${\mu}g/100g$), resulting in 33.3 RE of the converted vitamin A. Among 12 Korean rice cakes, Maeun-Tteokbokki and Modm-Chaltteok contained relatively high content of ${\beta}$-carotene with 205.11 and 41.33 ${\mu}g/100g$, respectively, while retinol was detected only in Maeun- Tteokbokki (1.65~10.45 ${\mu}g/100g$). In addition, among 8 bread products, 77.3 RE of pastry, 51.2 RE of buttercream- bread, and 41.4 RE of morning roll were found as the contents of the converted vitamin A.

• Journal of the Korean Society of Food Science and Nutrition
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• v.44 no.3
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• pp.418-424
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• 2015

The content of ${\beta}$-carotene in agricultural foods, such as seasonings, tea, vegetables, cereals, nuts & seeds, oils & fats, and fruits, were quantitatively analyzed using reversed-phase HPLC with an UV/visible detector. Standard reference material (SRM) 2385 was used as a control material to validate measurement of ${\beta}$-carotene in this study. Recovery percentage and relative standard deviation of ${\beta}$-carotene in SRM 2385 were 102% and 1.73%, respectively. Vegetables and tea contained relatively high concentrations of ${\beta}$-carotene (young barley powder, $17,293.95{\mu}g/100g$; raw young barley, $2,755.15{\mu}g/100g$; dried green tea leaves, $13,671.85{\mu}g/100g$; green tea powder, $7,579.04{\mu}g/100g$). Contents of ${\beta}$-carotene in nuts & seeds as well as oils & fats ranged from $11.32{\mu}g/100g$ in almond products (roasted with salt) to $58.56{\mu}g/100g$ in perilla seed oil. Among 20 fruits, a high content of ${\beta}$-carotene was found in apricots (raw), which contained $2,280.35{\mu}g/100g$.

• New & Renewable Energy
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• v.18 no.3
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• pp.43-59
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• 2022

The green premium is the most important feature of Korea's RE100 system. Green premium has three characteristics. The first, the cost of implementation is lower than that of other means of implementation. The second, it is linked with the RPS system to keep the means of implementing the green premium low. Third, the funds raised by the green premium are used to supply renewable energy to compensate for the additionality that the green premium does not have. When the entire industrial sector's electricity consumption is converted to renewable energy, the implementation cost of the green premium is estimated to be 3,377.4 billion won, and the REC purchase is estimated to incur the implementation cost of 6,576.4 billion won, which is 3.5 trillion more than the green premium. It was analyzed that an additional implementation cost of KRW 100 million would occur. In addition, in the case of solar PPA, it was analyzed that additional implementation costs of KRW 13,375.7 billion to KRW 16,162.3 billion were incurred. It was estimated that the renewable energy that could be supplied to the green premium would at least be sufficient for companies exporting to the US and EU. In addition, it was analyzed that when the fund created as a green premium is used for renewable energy supply, about 30.7% of the renewable energy supply through PPA can be supplied. However, as ESG is emphasized, green premium can be criticized by green washing because there is no additionality. There is also a limit to responding to the EU's CBAM. Therefore, companies can use the green premium depending on the situation, but it is more advantageous to use PPA, etc. The government needs to sufficiently maintain the supply of renewable energy using the fund to maintain the green premium.

• Current Photovoltaic Research
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• v.11 no.4
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• pp.134-143
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• 2023

Efforts are being made to respond to global warming. Interest in and demand for the private sector-led RE100 campaign is also increasing. Self-built solar power generation, one of the implementation tools for RE100, is not expanding. However, it can be an economical means of implementation in the long run. In this study, we intend to analyze the impact on the optimal ratio of self-solar power generation using HOMER simulation. OPR defines the optimal solar power generation ratio and looks into what changes there are in the optimal solar power ratio when self-power consumption increases and external power purchase price changes. As a result, the optimal rate of self-solar power generation has a low impact even if self-power consumption increases. As the external power unit price increases, the optimal ratio increases, and at a power unit price of 100 KRW/kWh, OPR is 24%; at 200 KRW/kWh OPR is 31%; and at 300 KRW/kWh OPR is 34%. This shows that the electricity price replaced during the life cycle has a high impact on the economic feasibility of solar power generation. However, when the external power unit price reached a certain level, the increase in OPR decreased. This shows that it is difficult for domestic companies to achieve RE100 based on the economic feasibility of solar energy alone. Therefore, efforts are needed to supply renewable energy in the public sector.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.7 no.2
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• pp.207-216
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• 1995

Flow and heat transfer characteristics of mixed convection heat transfer in a rectangular en-closure with various outlets are numerically investigated. The parameters considered here include Reynolds number, Grashof number and the position of outlet. The results show streamlines, isotherms, Nusselt numbers, velocity and temperature distributions. It has been shown that as Reynolds number increases, the size of cell decreases at Re$\leq$100 and increases at Re>100 for $Gr=10^4$. There is a minimum size of cells at Re=100, $Gr=10^4$. The maximum mean Nusselt number occurs at Re=400, $Gr=10^4$ and one right outlet. The mean Nusselt numbers can be formulated by the correlation equation $Nu=C{\cdot}Gr^a{\cdot}Re^b$.

• Fashion & Textile Research Journal
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• v.24 no.6
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• pp.812-824
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• 2022

This study proposes to develop a 3D printed re-entrant(RE) strip by shape memory thermoplastic polyurethane that can be deformed and recovered by thermal stimulation. The most suitable 3D printing infill density condition and temperature condition during shape recovery for mechanical behavior were confirmed. As the poisson's ratio indicated, the higher the recovery temperature, the closer the poisson's ratio to zero and the better the auxetic properties. After recovery testing for five minutes, it appeared that the shape recovery ratio was the highest at 70℃. The temperature range when the shape recovery ratio appeared to be more than 90% was a recovery temperature of more than 50℃ and 60℃ when deformed under a constant load of 100 gf and 300 gf, respectively. This indicated that further deformation occurred after maximum recovery when recovered at a temperature of 80℃, which is above the glass transition temperature range. As for REstrip by infill density, a shape recovery properties of 100% was superior than 50%. Additionally, as the re-entrant structure exhibited a shape recovery ratio of more than 90%, and exhibited auxetic properties. It was confirmed that the infill density condition of 100% and the temperature condition of 70℃ are suitable for REstrips for applying the actuator.

• Journal of Korea Foundry Society
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• v.29 no.3
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• pp.144-149
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• 2009

In this study, we investigated optimum condition of cooling plate method to obtain semi-solid AM100A Mg alloy with fine and globular morphology. AM100A Mg alloy were hot extruded at $380^{\circ}C$ extrusion temperature under extrusion ratio of 25 : 1 and ram speed of 2.4 mm/sec. Vickers hardness test, optical microscopy, scanning electron microscopy, and image analyzer were performed to identify the optimum conditions of cooling plate method. Optimum conditions of cooling plate method to fabricate semi-solid AM100A Mg alloy with fine and globular microstructures were achieved at a pouring temperature of $602^{\circ}C$ and the angle of cooling plate of 60 degree.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.36 no.3
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• pp.301-307
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• 2012

The characteristics of pressure loss in an asymmetric bifurcating tube were investigated numerically for steady inspiratory conditions. The loss coefficient K calculated for various asymmetry and flow-distribution ratios found in human lung airways showed a power-law dependence on the Reynolds number (Re) and length-to-diameter ratio (L/d), with different exponents for Re $\geq$ 100 and Re < 100. The fundamental characteristics of the asymmetric bifurcation are similar to the case of symmetric bifurcation. In addition, the effect of skewed inlet velocity profiles on the pressure loss was weak, and decreased with an increasing number of bifurcations.