정책효과를 분석하는데 있어 가장 중요한 이슈 중 하나는 선택편의(selection bias)를 통제하는데 있다. 효율적으로 선택편의를 통제하기 위하여 성향점수 매칭을 통한 이 중차분분석(PSM-DID)기법이 널리 사용되어오고 있으나, 이는 수혜집단과 비수혜집단에 포 함된 표본들이 집단에 따라 동질적인 정책효과를 지닌다는 과감한 가정을 필요로 한다. 본 연구는 수혜집단 내에서 이질적으로 나타나는 정책효과를 추정해보고자 성향점수 분위에 따 라 수혜집단과 비수혜집단을 매칭하여 정책수혜여부에 따른 매출성장효과를 분석하였다. 이 를 위하여 2020년 수행된 소재부품장비 R&D지원사업에 참여한 239개 중소기업을 수혜집단 으로 선정하였으며, 이들 기업의 성향점수를 산출한 뒤 8개 분위로 나누어 비수혜집단과 성 향점수 매칭을 수행하였다. 이후 분위별 이중차분분석을 통해 정책지원으로 인한 매출성장 률을 산출하였다. 그 결과 가장 낮은 분위의 집단에서 가장 큰 정책효과가 관찰되었으며, 3개 년 매출 성장률과 특허출원건수가 높은 기업집단들이 탁월한 정책효과를 누린 것으로 나타 났다. 연구의 결과는 성향점수 분위에 따른 이질적 정책효과 분석기법이 산업정책기획을 위 한 수혜기업의 선정기준, 지원범위 등을 조정하는데 효과적으로 사용될 수 있음을 시사한다.

Highly radioactive waste is solidified to restrict leaching, retain its shape, and maintain its structural stability to prevent it from affecting humans and the environment as much as possible. This operation should be performed consistently regardless of whether the waste is homogeneous or heterogeneous. However, currently, there are no specific performance requirements for heterogeneous waste in Korea. This study reviewed domestic research results and the status of overseas applications, and proposed immobilization requirements for heterogeneous waste to be applied in Korea. IAEA safety standards, domestic laws, and waste acceptance criteria were reviewed. The status of heterogeneous waste immobilization in countries such as the United States, France, and Spain was reviewed. Most countries treat heterogeneous waste by encasing it in concrete, and impose immobilization requirements on this concrete. Based on these data, safety standards for the thickness, compressive strength, and diffusion limit of this concrete material were proposed as immobilization requirements for heterogeneous waste disposal in Korea. Quantitative values for the above requirements need to be derived through quantitative assessments based on the characteristics of domestic heterogeneous waste and disposal facilities.

The conventional multi-scale modelling approach that predicts carbon nanotube (CNT) growth region in heterogeneous flame environment is computationally exhaustive. Thus, the present study is the first attempt to develop a zero-dimensional model based on existing multi-scale model where mixture fraction z and the stoichiometric mixture fraction zst are employed to correlate burner operating conditions and CNT growth region for diffusion flames. Baseline flame models for inverse and normal diffusion flames are first established with satisfactory validation of the flame temperature and growth region prediction at various operating conditions. Prior to developing the correlation, investigation on the effects of zst on CNT growth region is carried out for 17 flame conditions with zst of 0.05 to 0.31. The developed correlation indicates linear ( zlb=1.54zst +0.11) and quadratic ( zhb=zst(7-13zst )) models for the zlb and zhb corresponding to the low and high boundaries of mixture fraction, respectively, where both parameters dictate the range of CNT growth rate (GR) in the mixture fraction space. Based on the developed correlations, the CNT growth in mixture fraction space is optimum in the flame with medium-range zst conditions between 0.15 and 0.25. The stronger relationship between growth-region mixture-fraction (GRMF) and zst at the near field region close to the flame sheet compared to that of the far field region away from the flame sheet is due to the higher temperature gradient at the former region compared to that of the latter region. The developed models also reveal three distinct regions that are early expansion, optimum, and reduction of GRMF at varying zst.

The objectives of this paper are: (1) to conduct the thermal analyses of the disposal cell using COMSOL Multiphysics; (2) to determine whether the design of the disposal cell satisfies the thermal design requirement; and (3) to evaluate the effect of design modifications on the temperature of the disposal cell. Specifically, the analysis incorporated a heterogeneous model of 236 fuel rod heat sources of spent nuclear fuel (SNF) to improve the reality of the modeling. In the reference case, the design, featuring 8 m between deposition holes and 30 m between deposition tunnels for 40 years of the SNF cooling time, did not meet the design requirement. For the first modified case, the designs with 9 m and 10 m between the deposition holes for the cooling time of 40 years and five spacings for 50 and 60 years were found to meet the requirement. For the second modified case, the designs with 35 m and 40 m between the deposition tunnels for 40 years, 25 m to 40 m for 50 years and five spacings for 60 years also met the requirement. This study contributes to the advancement of the thermal analysis technique of a disposal cell.

In general, radioactive waste with high radioactivity is made into a solid form with performance such as leaching restriction, shape retention, and structural stability so that radioactive waste does not affect humans and the environment as much as possible. This should be applied equally to radioactive waste, whether homogeneous or heterogeneous. The requirements are stipulated in the “Low and Intermediate Level Radioactive Waste Delivery Regulations” notice of the Korea Nuclear Safety and Security Commission. On the other hand, the waste acceptance criteria for domestic disposal facilities require immobilization of heterogeneous waste when the activity concentration is above a certain level, but do not provide specific immobilization performance requirements. In this study, the immobilization requirements applied to heterogeneous radioactive waste in various overseas countries operating low and intermediate-level radioactive waste disposal facilities were studied. First, the IAEA’s safety standards for radioactive waste immobilization, domestic regulations, and disposal facility waste acceptance criteria were reviewed. Countries operating surface disposal facilities such as the United States, France, Spain, and Japan and countries operating underground disposal facilities such as Sweden and Finland were divided to review the current status of immobilization application to heterogeneous waste in overseas countries. When reviewing overseas cases, each country’s disposal methods, types of disposal waste, and waste treatment criteria were also reviewed. It was found that the immobilization requirements for heterogeneous radioactive waste vary depending on the disposal method and the type of barrier used to ensure disposal safety in each country. The common point is to surround heterogeneous radioactive waste within a concrete lining of a certain thickness, and to apply the thickness, compressive strength, and diffusion coefficient of the concrete lining as immobilization performance requirements. Through this study, the immobilization performance requirements for heterogeneous radioactive waste in various overseas countries that stably operate low- and intermediate-level radioactive waste were confirmed, which is expected to contribute to specifying the performance requirements for immobilization of heterogeneous radioactive waste in domestic disposal facilities.

In this study, the synthesis of nitrobenzene was carried out using sulfated silica catalyst. The study delved into H2SO4/SiO2 as a solid acid catalyst and the effect of its weight variation, as well as the use of a microwave batch reactor in the synthesis of nitrobenzene. SiO2 was prepared using the sol-gel method from TEOS precursor. The formed gel was then refluxed with methanol and calcined at a temperature of 600 °C. SiO2 with a 200-mesh size was impregnated with 98 % H2SO4 by mixing for 1 h. The resulting 33 % (w/w) H2SO4/SiO2 catalyst was separated by centrifugation, dried, and calcined at 600 °C. The catalyst was then used as a solid acid catalyst in the synthesis of nitrobenzene. The weights of catalyst used were 0.5; 1; and 1.5 grams. The synthesis of nitrobenzene was carried out with a 1:3 ratio of benzene to nitric acid in a microwave batch reactor at 60 °C for 5 h. The resulting nitrobenzene liquid was analyzed using GC-MS to determine the selectivity of the catalyst. Likewise, the use of a microwave batch reactor was found to be appropriate and successful for the synthesis of nitrobenzene. The thermal energy produced by the microwave batch reactor was efficient enough to be used for the nitration reaction. Reactivity and selectivity tests demonstrated that 1 g of H2SO4/SiO2 could generate an average benzene conversion of 40.33 %.

This work describes the synthesis and characterization of a heterogeneous catalyst consisting of piperazine-functionalized reduced graphene oxide decorated with Fe3O4 nanoparticles ( Fe3O4@rGO-NH), and the study of its catalytic activity as a magnetic heterogeneous catalyst for the Pechmann synthesis of coumarins. Catalyst Fe3O4@ rGO-NH was fully characterized by various techniques, including IR, XRD, TEM, VSM, TGA, and elemental analysis. Then, the catalyst was used as an efficient and easy-separable heterogeneous catalyst for the solvent-free synthesis of some coumarins by Pechmann reaction. The reaction was optimized in terms of reaction time and temperature, catalyst dosage, and the presence/absence of the solvent. Finally, the reusability of the catalyst was studied.

The electromembrane process, which has advantages such as scalability, sustainability, and eco-friendliness, is used in renewable energy fields such as fuel cells and reverse electrodialysis power generation. Most of the research to visualize the internal flow in the electromembrane process has mainly been conducted on heterogeneous ion exchange membranes, because of the non-uniform swelling characteristics of the homogeneous membrane. In this study, we successfully visualize the electroconvective vortices near the Nafion homogeneous membrane in PDMS-based microfluidic devices. To reinforce the mechanical rigidity and minimize the non-uniform swelling characteristics of the homogeneous membrane, a newly developed swelling supporter was additionally adapted to the Nafion membrane. Thus, a clear image of electroconvective vortices near the Nafion membrane could be obtained and visualized. As a result, we observed that the heterogeneous membrane has relatively stronger electroconvective vortices compared to the Nafion homogeneous membranes. Regarding electrical response, the Nafion membrane has a higher limiting current and less overlimiting current compared to the heterogeneous membrane. Based on our visualization, it is assumed that the heterogeneous membrane has more activated electroconvective vortices, which lower electrical resistance in the overlimiting current regime. We anticipate that this work can contribute to the fundamental understanding of the ion transport characteristics depending on the homogeneity of ion exchange membranes.

Recently, supercomputers have entered the era of exascale beyond petascale. Overcoming the exascale barrier, which is the biggest problem with a large number of computing nodes and energy efficiency, was possible by using GPUs for computation in artificial intelligence, machine learning, and various high-performance computations. As evidenced by this, seven out of the ten world’s highest performing supercomputers are heterogeneous computing systems using GPUs. Accordingly, we developed a tool that can easily and conveniently monitor multiple vendors GPUs to support heterogeneous computing systems that are widely used in artificial intelligence and high-performance computations.

To build a highly active photocatalytic system with high efficiency and low cast of TiO2, we report a facile hydrothermal technique to synthesize Ag2Se-nanoparticle-modified TiO2 composites. The physical characteristics of these samples are analyzed by X-ray diffraction, scanning electron microscopy with energy dispersive X-ray analysis, transmission electron microscopy and BET analysis. The XRD and TEM results show us that TiO2 is coupled with small sized Ag2Se nanoplate, which has an average grain size of about 30 nm in diameter. The agglomeration of Ag2Se nanoparticles is improved by the hydrothermal process, with dispersion improvement of the Ag2Se@TiO2 nanocomposite. Texbrite BA-L is selected as a simulated dye to study the photodegradation behavior of as-prepared samples under visible light radiation. A significant enhancement of about two times the photodegradation rate is observed for the Ag2Se@TiO2 nanocomposite compared with the control sample P25 and as-prepared TiO2. Long-term stability of Ag2Se@TiO2 is observed via ten iterations of recycling experiments under visible light irradiation.

In this study, the failure characteristic of the center floor of a front-wheel drive vehicle was investigated according to material. UHSS, Al6061-T6, CFRP, and CFRP-Al were used as materials. As the analysis condition, a fixed support was applied to the rear surface of the center floor and a forced displacement of 2 mm/sec was applied to the front surface. As the result, when comparing with the equivalent stress and strain energy according to the material, it was found that UHSS, Al6061-T6, CFRP, and CFRP-Al were higher in the order. Also, when comparing with the equivalent strain due to the material, it was shown that the equivalent strain was high in the order of Al6061-T6, UHSS, CFRP and CFRP-Al. As for the damage characteristic of the center floor according to the material, it was found that the highest structural stability was obtained when UHSS was used. However, it was found that it was good to utilize Al6061-T6 in order to acquire the structural stability along with the structure with the lighter weight.

초음파 탐상은 다양한 콘크리트 구조물의 비파괴검사에서 활용된다. 본 연구에서는 골재형상을 고려한 골재-모르타르 모델 생성과 초음파 전파 해석을 수행하였다. 실제 골재형상을 반영하기 위해 이미지처리를 통한 골재-모르타르 단면으로부터 모르타르와 골재 영역을 파악하고, 영역 경계형상을 보존하면서 격자를 생성하는 기법을 개발하였다. 개발된 기법에서는 모든 격자가 4각형으로 생성된다. 골재-모르타르 모델을 통해 초음파 전파 해석을 수행하였고 모델을 반무한체로 간주하기 위해 CALM 기반 경계흡수 조건을 적용하였다. 골재 및 결함을 포함한 이미지로부터 격자를 생성한 뒤, 결함 영역에 포함된 격자를 제거하여 공극결함을 모사하였다. 본격적인 결함탐지 전 선행 해석을 통해 모델 동특성을 고려한 적절한 가진 주파수를 결정 및 가진 신호형상을 설계하였다. 이후 case 별 초음파 전파 해석을 통해 신호를 획득하고 신호 에너지 맵핑 작업을 통해 내부 결함을 가시화 하였다. 가시화 결과, 골재에 의한 다수 반사 및 산란현상이 관찰되지만 결함부에서 신호 에너지는 가장 높게 나타났으며 모든 해석 case에서 결함위치 추정이 가능하였다. 또한 균열의 경우 형상파악도 가능하였다.

It is generally believed that the meaning of “Yi (泗)” in the Book of Songs has been nasal fluids since Mao Heng, and has been explained from the perspective of borrowing, phonetic and ideographic word-formation, etc. However, there are still seven questions about the exact meaning of “Si (泗)”, which arouses different doubts about it. From the perspectives of handed-down documents and unearthed documents, variant relationships, literary meanings, contexts, dialects and so on, the word “Yi (泗)” of “Ti Si Pang Tuo (涕泗滂沱)” should be “Yi (㳑)” meaning that the water is full and flowing out. Furthermore, “Yi (泗)” has heterogeneous relationships with “Yi (益)”, “Yi (㳑)”, “Yi (溢)”, “Yi (洫)” and “Yi (泆)”, and has homologous relationships with “Ti (涕)”, “Yi (洟)” and “Ti (嚏)”, and has an isomorphic relationship with “Si (泗)” of “Si Shui (泗水)”. These relationships can be used to collate unearthed and handed-down documents.

1990년대 한국 현대미술계의 지형 변화는 이데올로기 대립 구도의 붕괴, 세계성과 지역성의 충돌, 아날로그와 디지털 체계의 교차 등 당시 대내외 사회변동과 밀접한 관련이 있다. 그 시기 ‘신세대 미술작가’라 불린 일군의 젊은 세대 작가들은 이질적이고 복합적인 예술 활동을 벌였는데, 이들은 시대적인 구도 변화의 의미를 분명하게 포착하고 있었다. 작업 초기 신세대 작가로 호명되었던 이불은 초기 퍼포먼스부터 1990년대 이후 다양한 미술 활동들로 대내외 미술계를 넘나들었다. 본 논문은 이불의 미술 작업을 통해 우리 현대미술이 동시대성을 획득하게 된 맥락을 구체적으로 추적하고, 당대 우리 미술계 내 세대전환의 계기가 단순히 어느 한 시기의 일정 상황과 관계하는 것이라기보다 인식체계의 전환과 연관된 바임을 다루고자 하였다.