• 한국수소및신에너지학회논문집
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• 제33권6호
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• pp.707-714
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• 2022

Hydrogen production using solid oxide electrolysis cells (SOEC) is a promising technology because of its efficiency, cleanness, and scalability. Especially, high-power SOEC system has received a lot of attention from researchers. This study compared and analyzed the low-power and high-power SOEC system in term of economic. By using revenue requirement method, levelized cost of hydrogen (LCOH) was calculated for comparison. In addition, the sensitivity analysis was performed to determine the dependence of hydrogen cost on input variables. The results indicated that high-power SOEC system is superior to a low-power SOEC system. In the capital cost, the stack cost is dominant in both systems, but the electricity cost is the most contributed factor to the hydrogen cost. If the high-power SOEC system combines with a nuclear power plant, the hydrogen cost can reach 3.65 $/kg when the electricity cost is 3.28 ¢/kWh and the stack cost is assumed to be 574 $/kW.

• 품질경영학회지
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• 제51권1호
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• pp.55-65
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• 2023

Purpose: The purpose of this study is to propose an optimization process to improve product yield in the process using process data. Recently, research for low-cost and high-efficiency production in the manufacturing process using machine learning or deep learning has continued. Therefore, this study derives major variables that affect product defects in the manufacturing process using eXplainable Artificial Intelligence(XAI) method. After that, the optimal range of the variables is presented to propose a methodology for improving product yield. Methods: This study is conducted using the injection molding machine AI dataset released on the Korea AI Manufacturing Platform(KAMP) organized by KAIST. Using the XAI-based SHAP method, major variables affecting product defects are extracted from each process data. XGBoost and LightGBM were used as learning algorithms, 5-6 variables are extracted as the main process variables for the injection process. Subsequently, the optimal control range of each process variable is presented using the ICE method. Finally, the product yield improvement methodology of this study is proposed through a validation process using Test Data. Results: The results of this study are as follows. In the injection process data, it was confirmed that XGBoost had an improvement defect rate of 0.21% and LightGBM had an improvement defect rate of 0.29%, which were improved by 0.79%p and 0.71%p, respectively, compared to the existing defect rate of 1.00%. Conclusion: This study is a case study. A research methodology was proposed in the injection process, and it was confirmed that the product yield was improved through verification.

• Animal Bioscience
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• 제36권5호
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• pp.692-703
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• 2023

Objective: The main goals of this investigation were to i) assess the population structure and genetic diversity and ii) determine the efficiency of the ongoing breeding program in a closed flock of Angora rabbits through pedigree analysis. Methods: The pedigree records of 6,145 animals, born between 1996 to 2020 at NTRS, ICAR-CSWRI, Garsa were analyzed using ENDOG version 4.8 software package. The genealogical information, genetic conservation index and parameters based on gene origin probabilities were estimated. Results: Analysis revealed that, 99.09% of the kits had both parents recorded in the whole dataset. The completeness levels for the whole pedigree were 99.12%, 97.12%, 90.66%, 82.49%, and 74.11% for the 1st, 2nd, 3rd, 4th, and 5th generations, respectively, reflecting well-maintained pedigree records. The maximum inbreeding, average inbreeding and relatedness were 36.96%, 8.07%, and 15.82%, respectively. The mean maximum, mean equivalent and mean completed generations were 10.28, 7.91, and 5.51 with 0.85%, 1.19%, and 1.85% increase in inbreeding, respectively. The effective population size estimated from maximum, equivalent and complete generations were 58.50, 27.05, and 42.08, respectively. Only 1.51% of total mating was highly inbred. The effective population size computed via the individual increase in inbreeding was 42.83. The effective numbers of founders (f_e), ancestors (f_a), founder genomes (f_g) and non-founder genomes (f_ng) were 18, 16, 6.22, and 9.50, respectively. The fe/fa ratio was 1.12, indicating occasional bottlenecks had occurred in the population. The six most influential ancestors explained 50% of genes contributed to the gene pool. The average generation interval was 1.51 years and was longer for the sire-offspring pathway. The population lost 8% genetic diversity over time, however, considerable genetic variability still existed in the closed Angora population. Conclusion: This study provides important and practical insights to manage and maintain the genetic variability within the individual flock and the entire population.

• 한국수소및신에너지학회논문집
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• 제33권1호
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• pp.8-18
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• 2022

With rapid industrialization and population growth, fossil fuel use has increased, which has a significant impact on the environment. Hydrogen does not cause contamination in the energy production process, so it seems to be a solution, but it is essential to find an appropriate storage method due to its low efficiency. In this study, Mg-based alloys capable of ensuring safety and high volume and hydrogen storage density per weight was studied, and Mg₂NiH_x synthesized with Ni capable of improving hydrogenation kinetics. In addition, in order to improve thermal stability, a hydrogen storage composite material synthesized with CaO was synthesized to analyze the change in hydrogenation reaction. In order to analyze the changes in the metallurgical properties of the materials through the process, XRD, SEM, BET, etc. were conducted, and hydrogenation behavior was confirmed by TGA and hydrogenation kinetics analysis. In addition, in order to evaluate the impact of the process on the environment, the environmental impact was evaluated through "Material Life Cycle Assessments" based on CML 2001 and EI99' methodologies, and compared and analyzed with previous studies. As a result, the synthesis of CaO caused additional power consumption, which had a significant impact on global warming, and further research is required to improve this.

• 한국재료학회지
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• 제33권5호
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• pp.175-188
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• 2023

Water electrolysis holds great potential as a method for producing renewable hydrogen fuel at large-scale, and to replace the fossil fuels responsible for greenhouse gases emissions and global climate change. To reduce the cost of hydrogen and make it competitive against fossil fuels, the efficiency of green hydrogen production should be maximized. This requires superior electrocatalysts to reduce the reaction energy barriers. The development of catalytic materials has mostly relied on empirical, trial-and-error methods because of the complicated, multidimensional, and dynamic nature of catalysis, requiring significant time and effort to find optimized multicomponent catalysts under a variety of reaction conditions. The ultimate goal for all researchers in the materials science and engineering field is the rational and efficient design of materials with desired performance. Discovering and understanding new catalysts with desired properties is at the heart of materials science research. This process can benefit from machine learning (ML), given the complex nature of catalytic reactions and vast range of candidate materials. This review summarizes recent achievements in catalysts discovery for the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER). The basic concepts of ML algorithms and practical guides for materials scientists are also demonstrated. The challenges and strategies of applying ML are discussed, which should be collaboratively addressed by materials scientists and ML communities. The ultimate integration of ML in catalyst development is expected to accelerate the design, discovery, optimization, and interpretation of superior electrocatalysts, to realize a carbon-free ecosystem based on green hydrogen.

• 예술인문사회 융합 멀티미디어 논문지
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• 제6권8호
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• pp.577-584
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• 2016

무인항공기는 조종사 없이 자율적으로 비행하는 동력 비행체를 이야기한다. 최근 무인항공기는 동영상 촬영, 항공사진측량 등 다양한 분야에 적용이 되고 있으며 특히 공간정보 관련 분야에서 무인항공 사진측량 기술은 자료 취득의 신속성과 경제성 때문에 많은 주목을 받고 있다. 하지만 무인항공측량 기술에 대한 분석적인 연구는 부족한 실정이다. 본 연구에서는 무인항공측량을 위한 장비에 대한 조사를 수행하고 지형모델 및 정사영상을 효과적으로 생성하기 위한 무인항공측량 기술과 트랜드 분석을 수행하였다. 연구를 통해 회전익 및 고정익 무인항공기의 특징 및 활용분야를 파악하였다. 또한 무인항공측량의 공정에서 새로운 측량방법을 적용하여 개선할 수 있는 방법을 제시하였다. 향후 지형모델 및 정사영상 제작을 위한 무인항공측량에 대한 분석적인 연구가 이루어진다면 공간정보 관련 산업의 효율성이 크게 증대될 것으로 기대된다.

• Composites Research
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• 제36권2호
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• pp.69-79
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• 2023

유수분리는 석유 생산, 폐수 처리 및 식품 가공을 포함한 다양한 산업 응용 분야와 해양 기름 유출과 같은 환경 분야에서 중요한 과정이다. 물-기름 혼합물의 분리 효율은 혼합물의 유형, 기름과 물의 상태, 적용하고자 하는 기술을 포함한 여러 요인에 의해 영향을 받을 수 있으며, 수년에 걸쳐 물리적, 화학적 및 생물학적 방법으로 물과 기름을 분리하기 위한 다양한 기술이 개발되어 오고 있다. 본 논문은 중력에 의한 분리, 원심 분리, 흡착재, 필터 등을 이용한 유수분리를 포함하여 물-기름 분리에 사용할 수 있는 다양한 방법과 기술에 대해 개략적으로 설명하고자 한다. 각 방법의 장점과 한계를 최근 연구 동향 및 향후 전망과 함께 논의한다. 또한 본 논문에서는 지속 가능하고 환경 친화적인 접근 방식에 특히 중점을 두고 유수분리 분야의 향후 연구와 산업 적용을 위한 방향성을 제시하고자 한다. 결론적으로 본 논문에서는 유수분리 분야의 연구자 및 산업 종사자에게 유용할 수 있는 최근 유수 분리 기술에 대한 포괄적인 개요를 제공하고자 한다.

• Smart Structures and Systems
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• 제31권3호
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• pp.283-299
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• 2023

Structural stability of floating platforms has long since been a crucial issue in the field of marine engineering. Excessive motions would not only deteriorate the operating conditions but also seriously impact the safety, service life, and production efficiency. In recent decades, several control devices have been proposed to reduce unwanted motions, and an attractive one is the tuned heave plate (THP). However, the THP system may reduce or even lose its effectiveness when it is mistuned due to the shift of dominant wave frequency. In the present study, a novel adaptive tuned heave plate (ATHP) is proposed based on inerter by adjusting its inertance, which allows to overcome the limitation of the conventional THP and realize adaptations to the dominant wave frequencies in real time. Specifically, the analytical model of a representative semisubmersible platform (SSP) equipped with an ATHP is created, and the equations of motion are formulated accordingly. Two optimization strategies (i.e., J₁ and J₂ optimizations) are developed to determine the optimum design parameters of ATHP. The control effectiveness of the optimized ATHP is then examined in the frequency domain by comparing to those without control and controlled by the conventional THP. Moreover, parametric analyses are systematically performed to evaluate the influences of the pre-specified frequency ratio, damping ratio, heave plate sizes, peak periods and wave heights on the performance of ATHP. Furthermore, a Simulink model is also developed to examine the control performance of ATHP in the time domain. It is demonstrated that the proposed ATHP could adaptively adjust the optimum inertance-to-mass ratio by tracking the dominant wave frequencies in real time, and the proposed system shows better control performance than the conventional THP.

• Animal Bioscience
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• 제35권10호
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• pp.1556-1565
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• 2022

Objective: Tan lambs (n = 36, 3 mo old, 19.1±0.53 kg) were used to assess effects of dietary guanidinoacetic acid (GAA) and rumen-protected methionine (RPM) on growth performance, carcass traits, meat quality, and serum parameters. Methods: Lambs were randomly assigned to three treatment groups, with 6 pens per group and 2 lambs per pen. Dietary treatments were: basal diet alone (I); basal diet supplemented with 0.08% GAA+0.06% RPM (II); and basal diet supplemented with 0.08% GAA+0.08% RPM (III). Diets were provided three times a day for 90 d. Intake per pen was recorded daily and individual lamb body weight (BW) was measured monthly. Carcass traits were measured after slaughter and meat quality at the end of the experiment, blood samples were taken on a subgroup of lambs for analysis of indicators mostly related to protein metabolism. Results: Final BW and average daily gain for the first and second month, and for the entire experiment were greater in Treatment II compared to Treatment I (p<0.05), whereas feed to gain ratio was lower (p<0.05). Treatment II had the optimal dressing percentage and net meat weight proportion, as well as crude protein and intramuscular fat concentrations in muscles. Treatment II improved meat quality, as indicated by the greater water holding capacity, pH after 45 min and 48 h, and lower shear force and cooking loss. Dietary supplementation of GAA and RPM also increased the meat color a^* and b^* values at 24 h. Finally, Treatment II increased total protein, and serum concentrations of albumin and creatinine, but decreased serum urea nitrogen concentrations, indicating improved protein efficiency. Conclusion: In this study, 0.08% GAA+0.06% RPM supplementation improved growth performance and meat quality of Tan lambs.

• 경제분석
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• 제25권3호
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• pp.30-69
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• 2019

본 연구는 국제무역에 참여하고 있는 우리나라의 기업들을 대상으로 수출입이 기업의 노동수요에 미치는 영향을 살펴보았다. 통계청의 기업활동조사 데이터를 이용하여 2006년부터 2014년까지 제조업 24개 업종에 속해 있는 기업들의 수출입이 노동수요에 미치는 영향을 시스템 GMM 방법을 사용하여 분석하였다. 분석 결과, 생산성이 높은 기업에서는 수출이 늘어나면서 생산 확대를 위한 노동수요가 창출되는 효과가 나타난 반면 생산성이 낮은 기업에서는 이러한 효과가 유의하게 나타나지 않았다. 그러나 기업이 오프쇼어링을 이용하여 국내업무를 해외로 재배치한 경우, 수출이 유발하는 노동수요 증가 효과가 축소되는 것으로 분석되었다. 한편, 수입증대는 기업의 노동수요를 감소시키는 것으로 나타나는 데, 이는 수입제품이 노동을 대체하는 효과 때문인 것으로 보인다. 반면 기업이 오프쇼어링을 이용하는 경우, 생산 효율성 증대로 수입의 노동수요 감소효과가 완화되는 것으로 나타났다. 본 연구의 결과는 수출입이 기업의 고용에 미치는 영향은 기업의 생산성 및 글로벌 아웃소싱 참여 여부에 따라 달라질 수 있음을 시사한다.