• 한국수소및신에너지학회논문집
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• 제32권6호
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• pp.470-476
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• 2021

In the near future, with the urgent requirement of environmental protection, hydrogen based energy system is essential. However, at the present time, most of the hydrogen is produced by reforming, which still produces carbon dioxide. This study proposes a high-power electrolytic hydrogen production system based on solid oxide electrolysis cell with no harmful emissions to the environment. Besides that, the parametric study and optimization are also carried to examine the effect of individual parameter and their combination on system efficiency. The result shows that the increase in steam conversion rate and hydrogen molar fraction in incoming stream reduces system efficiency because of the fuel heater power increase. Besides, the higher Faraday efficiency does not always result a higher system efficiency.

• Nuclear Engineering and Technology
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• 제55권2호
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• pp.587-594
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• 2023

This study investigates the impacts of nuclear energy consumption on environmental quality from a different perspective by focusing on carbon dioxide (CO2) emissions, ecological footprint, and load capacity factor. In this context, the South Korea case, which is a leading country producing and consuming nuclear energy, is investigated by considering also economic growth, and the 1997 Asian crisis from 1977 to 2018. To this end, the study employs the autoregressive distributed lag (ARDL) approach. Different from previous literature, this study proposes a load capacity curve (LCC) and tests the LCC and environmental Kuznets curve (EKC) hypotheses simultaneously. The analysis results reveal that (i) the LCC and EKC hypotheses are valid in South Korea; (ii) nuclear energy has an improving effect on the environmental quality; (iii) renewable energy does not have a significant long-term impact on the environment; (iv) the 1997 Asian crisis had an increasing effect on the load capacity factor; (v) South Korea has not yet reached the turning point, identified as $55,411, where per capita income improves environmental quality. Overall, the results show the validity of the LCC and EKC hypotheses and prove the positive contribution of nuclear energy to South Korea's green development strategies.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2022년도 봄 학술논문 발표대회
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• pp.17-18
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• 2022

Carbon dioxide emissions in the construction sector account for 38% of all industries, and environmental destruction is occurring due to indiscriminate use of natural resources. The purpose of this study is to develop by-product aggregate Non-Sintered Cement(NSC) that can replace sand used as natural aggregate and Portland cement. Therefore, Ground Granulated Blast Furnace Slag, Type C Fly Ash and Type F Fly Ash are used to replace cement, and water granulated ferro-nickel slag(FNS) is used to replace aggregate. The flow, compressive strength and flexural strength of the formulation using sand as an aggregate and the formulation replacing 100% FNS were compared. As a result of the experiment, the formulation using FNS had higher overall strength than the formulation using sand, and as the substitution rate of Type C fly ash increased, the strength was the best. Formulation using FNS is more fluid than using sand. Through this study, we show the possibility of 100% substitution of FNS and its applicability to secondary concrete products of by-product aggregate NSC.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2023년도 봄 학술논문 발표대회
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• pp.297-298
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• 2023

In the concrete industry, efforts are being made to reduce CO₂ emissions, and technologies that collect, store, and utilize CO₂ have recently been studied. This study analyzed the change in compressive strength after the accelerated carbonation test of Non-Sintered Cement(NSC) mortar. Type C Fly Ash and Type F Fly Ash were mixed in a 1:1 ratio and then mixed with Blast Furnace Slag fine powder to produce NSC. The mortar produced was cured underwater until the target age. In addition, an accelerated carbonation test was conducted under the condition of a concentration of 5 (±1.0%) of CO₂ gas for 14 days. The mortar compressive strength was measured before and after 14 days of accelerated carbonation test based on the 7th and 28th days of age. As a result of the experiment, the compressive strength was improved in all binder. In general, the compressive strength of NSC mortar subjected to the accelerated carbonation test was similar to that of Ordinary Portland Cement(OPC) mortar not subjected to the accelerated carbonation test.

• East Asian Economic Review
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• 제28권1호
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• pp.3-35
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• 2024

This paper utilizes social network analysis to examine the structural characteristics and trade dynamics of the renewable energy (hydropower, wind energy, and solar energy) trade network within the RCEP region from 2011 to 2020. The findings reveal: (1) The renewable energy trade network within the RCEP exhibits dynamism, heterogeneity, and an uneven development. The solar energy network is the most balanced and stable, while the wind energy network lags and shows marked fluctuations, with the hydropower network falling between these two. This demonstrates the diversity of energy trade within the region. (2) China, Singapore, and Japan are identified as the key exporting and importing countries, with Vietnam showing substantial growth potential. Individual analyses shed light on the stark disparities in trade status among nations, reflecting the diverse roles and future potential of member countries. (3) The QAP regression analysis reveals a significant influence of environmental pressure, particularly carbon dioxide emissions, on the renewable energy trade network. This study contributes to promoting environmental sustainability and energy security in the RCEP region and provides empirical evidence for global renewable energy trade strategies.

• 한국환경과학회지
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• 제22권2호
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• pp.139-149
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• 2013

Anthropogenic increases in greenhouse gas concentrations, primarily through radiative forcing from carbon dioxide, continue to challenge earth's climate. This study quantified $CO_2$ storage and uptake by dominant forest types and age classes in the middle region of Korea. In addition, the role of forest landscapes in reducing atmospheric $CO_2$ against $CO_2$ emissions based on energy consumption was evaluated. Mean $CO_2$ storage and uptake per unit area by woody plants for three forest types and four age classes were estimated applying regression equations derived to quantify $CO_2$ storage and uptake per tree; and computations per soil unit area were also performed. Total $CO_2$ storage and uptake by forest landscapes were estimated by extrapolating $CO_2$ storage and uptake per unit area. Results indicated mean $CO_2$ storage per unit area by woody plants and soils was higher in older age classes for the same forest types, and higher in broadleaved than coniferous forests for the same age classes, with the exception of age class II (11-20 years). $CO_2$ storage by broadleaved forests of age class V (41-50 years) averaged 662.0 t/ha (US$331.0 hundred/ha), highest for all forest types and age classes evaluated. Overall, an increased mean $CO_2$ uptake per unit area by woody plants was evident for older age classes for the same forest types. However, decreased $CO_2$ uptake by broadleaved forests at age class V was observed, compared to classes III and IV with an average of 27.9 t/ha/yr (US$14.0 hundred/ha/yr). Total $CO_2$ storage by woody plants and soils in the study area was equivalent to 3.4 times the annual $CO_2$ emissions, and woody plants annually offset the $CO_2$ emissions by 17.7%. The important roles of plants and soils were associated with 39.1% of total forest area in South Korea, and $CO_2$ emissions comprised 62.2% of the total population. Therefore, development of forest lands may change $CO_2$ sinks into sources. Forest landscape management strategies were explored to maintain or improve forest roles in reducing atmospheric $CO_2$ levels.

• Journal of Biosystems Engineering
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• 제39권2호
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• pp.76-86
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• 2014

Purpose: The objective of this study was to measure emissions of gases (ammonia ($NH_3$), hydrogen sulfide ($H_2S$) and carbon dioxide ($CO_2$)), volatile organic compounds (VOC) and odor from two shallow pit pig nursery rooms. Gas and odor reduction practices for swine operations based on the literature were also discussed. Methods: This study was conducted for 60 days at a commercial swine nursery facility which consisted of four identical rooms with mechanical ventilations. Two rooms (room 1 (R1) and room 2 (R2)) with different pig numbers and ventilation rates were used in this study. The pig manure from both the R1 and R2 were characterized. Indoor/outdoor temperatures, ventilation rates/duration, $NH_3$, $H_2S$, $CO_2$, and VOC concentrations of the ventilation air were measured periodically (3-5 times/week). Odor concentrations of the ventilations were measured two times on two days. Three different types of gas and odor reduction practices (diet control, chemical method, and biological method) were discussed in this study. Results: The volatile solids to total solids ratio (VS/TS) and crude protein (CP) value of pig manure indicated the pig manure had high potential for gas and odor emissions. The $NH_3$, $H_2S$, $CO_2$ and VOC concentrations were measured in the ranges of 1.0-13.3, 0.1-5.7, 1600-3000 and 0.0-1.83 ppm, respectively. The $NH_3$ concentrations were found significantly higher than $H_2S$ concentrations for both rooms. The odor concentrations were measured in the range of $2853-4432OU_E/m^3$. There was significant difference in odor concentrations between the two rooms which was due to difference in pig numbers and ventilation duration. The literature studies showed that simultaneous use of dietary control and biofiltration practices will be more effective and environmentally friendly for gas and odor reductions from pig barns. Conclusions: The gas and odor concentrations measured in the ventilation air from the pig rooms indicate an acute need for using gas and odor mitigation technologies. Adopting diet control and biofiltration practices simultaneously could be the best option for mitigating gas and odor emissions from pig barns.

• 한국축산시설환경학회지
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• 제16권3호
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• pp.175-180
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• 2010

본 시험은 혐기조건하에서 돈슬러리로부터 발생하는 온실가스 연속측정 기술을 습득하고, 이를 이용해 온실가스의 일종인 메탄 발생량 및 시간대별 배출량 변화를 알아보기 위한 목적으로 수행하였으며, 그 결과는 다음과 같다. 1. TGA의 16 site에서 측정한 값들의 평균값은 2.437 ppm이었으며 표준편차는 0.024 ppm이었다. 각 site에서 평균값과 비교한 표준편차는 10% 이내였다. 따라서 각 site에서 측정된 값은 일정한 농도를 보인다고 할 수 있다. 2. 돈분뇨 액비에서 배출되는 $CH_4$을 측정하기 위해 돈분뇨 액비 저장조에서 액비를 샘플링하여 그것을 들통에 보관하였고, 들통에서 배출되는 $CH_4$ 배출량을 측정하였다. 들통 1, 2, 3의 $CH_4$ 배출량은 각각 413.9, 373.8, 그리고 391.9 ${\mu}g\;m^{-2}\;s{-1}$였고 세 들통의 평균값은 393.2 ${\mu}g\;m^{-2}\;s{-1}$이었다.

• 한국기후변화학회지
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• 제4권3호
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• pp.235-244
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• 2013

이산화탄소 배출량 산정법은 IPCC 지침에 따라 4가지 산정등급(Tier)으로 구분된다. 본 연구에서는 LNG를 연료로 사용하는 기체 화력발전소에서의 2011년 3월부터 5월까지의 이산화탄소 배출량을 Tier 3과 4의 방법에 따라 산정하여 그 결과를 물질 수지식에 따른 이론적 배출량과 비교하였다. Tier 3과 이론적 배출량의 결과는 유사하게 나타난 반면, Tier 4의 경우 이론적 배출량에 비해 최대 17% 가량 높게 산정되는 것으로 나타났다. 비교 결과는 연속 측정 장비에서의 결측, 비정상, 무효 자료 대체로 인한 오차 가능성을 제시한다. 하지만 정상적인 자료만을 사용하여 상대적인 결과 차이를 볼 경우에도 차이는 다소 경감하나 여전히 존재한다. 이러한 차이는 Tier 4에 해당하는 연속측정 기기 자체, 특히, 유량측정기의 오류 및 정확도에 의한 것으로 보인다.

• Animal Bioscience
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• 제37권2호
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• pp.173-183
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• 2024

Objective: This study aimed to evaluate whether the methane (CH₄) to carbon dioxide (CO₂) ratio (CH₄/CO₂) and methane-related traits obtained by the sniffer method can be used as indicators for genetic selection of Holstein cows with lower CH₄ emissions. Methods: The sniffer method was used to simultaneously measure the concentrations of CH₄ and CO₂ during milking in each milking box of the automatic milking system to obtain CH₄/CO₂. Methane-related traits, which included CH₄ emissions, CH₄ per energy-corrected milk, methane conversion factor (MCF), and residual CH₄, were calculated. First, we investigated the impact of the model with and without body weight (BW) on the lactation stage and parity for predicting methane-related traits using a first on-farm dataset (Farm 1; 400 records for 74 Holstein cows). Second, we estimated the genetic parameters for CH₄/CO₂ and methane-related traits using a second on-farm dataset (Farm 2; 520 records for 182 Holstein cows). Third, we compared the repeatability and environmental effects on these traits in both farm datasets. Results: The data from Farm 1 revealed that MCF can be reliably evaluated during the lactation stage and parity, even when BW is excluded from the model. Farm 2 data revealed low heritability and moderate repeatability for CH₄/CO₂ (0.12 and 0.46, respectively) and MCF (0.13 and 0.38, respectively). In addition, the estimated genetic correlation of milk yield with CH₄/CO₂ was low (0.07) and that with MCF was moderate (-0.53). The on-farm data indicated that CH₄/CO₂ and MCF could be evaluated consistently during the lactation stage and parity with moderate repeatability on both farms. Conclusion: This study demonstrated the on-farm applicability of the sniffer method for selecting cows with low CH₄ emissions.