The research aimed to develop a high-efficiency plate-type heat exchanger for exhaust gas using computational fluid dynamics (CFD) thermal analysis based on the plate shape, and to identify the optimal shape. Following this, a water/air plate heat exchanger was manufactured, and its characteristics were studied experimentally. As the Re number increases on the gas (or air) side, the heat transfer rate increases significantly, whereas an increase in the Re number on the water side leads to a smaller increase in heat transfer. This is attributed to the larger convective heat resistance on the gas side, causing a substantial reduction in gas-side heat resistance as gas velocity increases, resulting in a considerable overall reduction in heat resistance. The fluid flow pressure drop showed similar results between the CFD calculations and experimental outcomes.

PURPOSES : This study aimed to develop high-performance concrete repair materials for the cross-sectional repair of deteriorated bridge concrete. METHODS : To derive the optimal mix using the dry shotcrete method, experiments were conducted to develop an appropriate performance in terms of durability and watertightness based on basic experiments on materials. By mixing silica fume, GGBFS, and natural fibers, this study compared the differences in each variable. Each variable was compared using compressive strength, flexural strength, plastic shrinkage, chlorine ion penetration resistance, and freeze-thaw tests. RESULTS : By mixing silica fume and natural fibers, watertightness and durability were secured, and by adding an expansion material and polymer powder, a material that exhibited suitable performance as a repair material was developed. The material demonstrated suitable performance in terms of compressive strength, freeze–thaw resistance, plastic shrinkage crack resistance, and chlorine ion penetration resistance. CONCLUSIONS : The repair material developed in this study has a higher performance than repair mortar, and because it uses a dry shotcrete method, the process and post-processing are simpler than the wet shotcrete method; therefore, it is believed to be more efficient for repair work.

본 연구에서는 수소 자원의 활용도가 높아짐에 따라 수소 저장 용기의 내진 성능을 평가하기 위해 수소 저장 시설을 방문하여 현장 조사를 수행하였다. 외관 조사 중, 수조 저장 용기의 지지부에서 부식이 진행됨을 확인하였고, 이에 대한 대책안 으로 내부식성 재료인 CFRP로 대체하여 성능을 평가, 검증하였다. 이를 위해 현장 조사 결과를 바탕으로 상용 유한요소해석 프 로그램인 ABAQUS를 사용하였으며, 해석 결과 CFRP로 제작된 수소 저장 용기의 지지부는 강재 대비 약 12배 이상 뛰어난 성 능을 보였다. Hashin Damage Criteria를 기반으로 CFRP 지지부의 안전성 검토를 수행한 결과 최대 손상 지수가 0.065로 확인되 었다. 기초부 콘크리트의 경우, 쪼갬 및 휨 인장 응력에 대한 안전성을 검토하였으며, 허용 강도 대비 7~36%의 안전도를 보였 다. 이를 근거로 CFRP를 수소 저장 용기의 지지부에 적용하는 것은 합리적이며, 뛰어난 경제성을 보인다. 다만, 이러한 결과는 수치 해석에 의하므로 실규모 지진동 모사 시험을 통해 해석 모델의 신뢰성을 보충할 필요가 있다.

본 연구의 목적은 국내 시장에 진출한 다국적기업 현지 자회사의 ESG 경영과 디지털 역량이 재무적 성과에 미치는 영향을 분석해 보고, 현지 ESG 경영과 디지털 역량 간의 상호작용 효과를 살펴보는 데 있다. 이를 위해 한국에 진출한 다국적기업 현지 자회사에 대한 실증분석을 시행한 결과, 현지 ESG 경영과 자회사가 보유한 디지 털 역량 모두 재무적인 성과를 증진하는 것으로 나타났다. 한편, 자회사의 ESG 경영과 보유한 디지털 역량은 유 의한 정(+)의 상호작용 효과를 나타내지 못하는 것으로 확인되었다. 오히려 자회사의 현지 ESG 경영과 디지털 역량은 부(-)의 유의한 상호작용 효과가 확인되는 분석결과를 보였다. 이러한 결과는 현지 ESG 경영과 자회사의 디지털 역량이 현지에서의 재무적 성과를 개선할 수 있다는 것을 보여준다. 그뿐만 아니라, 자회사의 디지털 역 량과 ESG 경영은 서로가 긍정적인 재무적 성과로 이어지는 것에 각자가 걸림돌이 될 수 있는 대체재 관계라는 사실을 방증한다. 이는 다국적기업 현지 자회사가 전략적 측면에서 어떤 역할을 맡을 것인지에 따라 ESG 경영과 디지털 역량 중 하나만을 선택해 역량을 결집하는 것이 바람직함을 시사한다. 본 연구의 결과는 현지에서 쓸 수 있는 비용이 한정되어 둘 중 하나만을 선택해야 하는 현실을 마주한 현지 자회사가 ESG 경영과 디지털 역량 발 현 둘 모두에 충실하기보다는 하나의 전략 실행에만 유무형의 경영 자원을 집중함으로써 재무적 성과를 극대화할 수 있다는 사실을 환기하였다.

This study successfully prepared high-porosity aluminosilicate fibrous porous ceramics through vacuum suction filtration using aluminosilicate fiber as the primary raw material and glass powder as binder, with the appropriate incorporation of glass fiber. The effects of the composition of raw materials and sintering process on the structure and properties of the material were studied. The results show that when the content of glass powder reached 20 wt% and the samples were sintered at the temperature of 1,000 °C, strong bonds were formed between the binder phase and fibers, resulting in a compressive strength of 0.63 MPa. When the sintering temperatures were increased from 1,000 °C to 1,200, the open porosity of the samples decreased from 89.08 % to 82.38 %, while the linear shrinkage increased from 1.13 % to 10.17 %. Meanwhile, during the sintering process, a large amount of cristobalite and mullite were precipitated from the aluminosilicate fibers, which reduced the performance of the aluminosilicate fibers and hindered the comprehensive improvement in sample performance. Based on these conditions, after adding 30 wt% glass fiber and being sintered at 1,000 °C, the sample exhibited higher compressive strength (1.34 MPa), higher open porosity (89.13 %), and lower linear shrinkage (5.26 %). The aluminosilicate fibrous porous ceramic samples exhibited excellent permeability performance due to their high porosity and interconnected three-dimensional pore structures. When the samples were filtered at a flow rate of 150 mL/min, the measured pressure drop and permeability were 0.56 KPa and 0.77 × 10-6 m2 respectively.

This paper describes the seismic performance evaluation of reinforced concrete bridge columns under constant and varying axial forces. For this purpose, nine identical circular reinforced concrete columns were designed seismically by KIBSE (2021) and KCI (2021). A comparison of lateral forces with theoretical strength shows that the safety factor for columns under varying axial forces is less marginal than those under constant axial forces. In addition, columns under varying axial forces exhibit significant fluctuations in the hysteretic response due to continuously varying axial forces. This is particularly prominent when many varying axial force cycles within a specific lateral loading cycle increase. Moreover, the displacement ductility of columns under varying axial forces does not meet the code-specified required ductility in the range of varying axial forces. All varying axial forces affect columns' strength, stiffness, and displacement ductility. Therefore, axial force variation needs to be considered in the lateral strength evaluation of reinforced concrete bridge columns.

The ductility of the system based on the capacity of each structural member constituting the seismic force-resisting system is a significant factor determining the structure’s seismic performance. This study aims to provide a procedure to supplement the current seismic design criteria to secure the system’s ductility and improve the seismic performance of the steel ordinary moment frames. For the study, a nonlinear analysis was performed on the 9- and 15-story model buildings, and the formation of collapse mechanisms and damage distribution for dynamic loads were analyzed. As a result of analyzing the nonlinear response and damage distribution of the steel ordinary moment frame, local collapse due to the concentration of structural damage was observed in the case where the influence of the higher mode was dominant. In this study, a procedure to improve the seismic performance and avoid inferior dynamic response was proposed by limiting the strength ratio of the column. The proposed procedure effectively improved the seismic performance of steel ordinary moment frames by reducing the probability of local collapse.

Hybrid nanocomposites of aluminium (NHAMMCs) made from AA5052 are fabricated via stir casting route by reinforcing 12 wt% Si3N4 and 0.5 wt% of graphene for usage in aeronautical and automotive applications due to the lower density and higher strength to weight proportion. The wear characteristics of the NHAMMCs are evaluated for different axial load, rotational speed, sliding distance and sliding time based on Box-Behnken design (BBD) of response surface methodology (RSM). Orowan strengthening mechanism is identified from optical image which improves the strength of the composite. Outcomes show that with higher axial load and rotational speed, there is substantial increase in wear loss whereas with increased sliding distance and sliding time there is no considerable increase in wear loss due to the lubricating nature of the reinforced graphene particles since it has higher surface area to volume ratio. Besides, artificial intelligence approach of neuro-fuzzy (ANFIS) model is developed to predict the output responses and the results are compared with the regression model predictions. Prediction from ANFIS outplays the regression model prediction.

Liquid phase exfoliation of natural graphite is an industrially effective solution for graphene preparation. However, many countries have identified natural graphite as a strategic resource and restricted its mining. In this report, we used abundant and readily available needle coke (NC) as a graphene exfoliation precursor and sodium carboxymethyl cellulose (CMC) as a dispersant to prepare a sandwich structured conductive graphitized NC nanosheets (GNCNs) by liquid phase exfoliation, freeze-drying and high-temperature graphitization, in which a graphene layer is sandwiched between two thin CMC layers. CMC could increase the liquid absorption and retention ability of the conductive agent and improve the migration rate of lithium ions. The highly ordered graphene layer could accelerate the transmission of electrons. The GNCNs with 0.4 wt% CMC addition showed good rate performance (144.6 mAh g− 1 at 5 C) and high cycle stability (96.2% after 200 cycles at 1 C) for LiFePO4 (LFP) battery. The traditional Super-P (SP) conductive agent exhibited low-rate performance (113.9 mAh g− 1 at 5 C) and cycle performance (89.9% after 200 cycles at 1 C). This study offers a novel approach to selecting graphene precursors and has promising applications for conductive additives in high-performance LFP batteries.

A carbon matrix for high-capacity Li/Na/K-alloy-based anode materials is required because it can effectively accommodate the variation in the volume of Li/Na/K-alloy-based anode materials during cycling. Herein, a nanostructured porous polyhedral carbon (PPC) was synthesized via a simple two-step method consisting of carbonization and selective acid etching, and their electrochemical Li/Na/K-ion storage performance was investigated. The highly uniform PPC, with an average particle size of 800 nm, possesses a porous structure and large specific surface area of 258.82 cm2 g– 1. As anodes for Li/Na/K-ion batteries (LIBs/NIBs/KIBs), the PPC matrix exhibited large initial reversible capacity, fast rate capability (LIB: ~ 320 mAh g– 1 at 3C; NIB: ~ 140 mAh g– 1 at 2C; KIB: ~ 110 mAh g– 1 at 2C), better cyclic performance (LIB: ~ 550 mAh g– 1; NIB: ~ 210 mAh g– 1; KIB: ~ 190 mAh g– 1 at 0.2C over 100 cycles), high ionic diffusivity, and excellent structural robustness upon cycling, which demonstrates that the PPC matrix can be highly used as a carbon matrix for high-capacity alloy-based anode materials for LIBs/NIBs/KIBs.

Abstract Purpose : This study sought to find ways to improve awareness and ethics of opticians' code of ethics. Methods : A survey was conducted on 102 Korean opticians to investigate the awareness and performance satisfaction of the optician's code of ethics, as well as differences according to gender, age, education level, work experience, and workplace. Results : This study found no gender-based differences in opticians’ awareness and satisfaction with the code of ethics. However, age and education significantly influenced these factors, with higher levels observed among opticians in their 20s and 30s, particularly those in the early stages of their careers. Furthermore, a positive correlation was noted between education level and both awareness and satisfaction. The study revealed that opticians with volunteer experience exhibited higher awareness and satisfaction with the code of ethics than those without. This suggests that volunteering, which fosters professional identity and social responsibility, influences opticians’ ethical awareness. Additionally, groups with a strong interest in foreign languages and self-development demonstrated higher ethical awareness and satisfaction. Conclusion : This study underscores the need for enhanced ethical awareness among opticians. It advocates for the development of methods, case studies, and guidelines to address ethical issues not covered by the existing code, thereby revitalizing ethical practices in the profession. In addition, it is judged that active promotion and education on the code of ethics and professional ethics are necessary for the continuing education of opticians. Key words : Awareness, Code of ethics, Performance satisfaction

ROK Navy Landing Ship Fast(LSF-II) is equipped with special equipment that is not compatible with other combat ships due to special missions. So there are almost no maintenance capabilities except for simple repair parts replacement and maintenance parts. The researcher determined that the way to solve these problems was to apply Performance Based Logistics (PBL), and reviewed the cases of PBL applications abroad and domestically. To confirm the current maintenance capability, we visited LSF-II operation unit to identify maintenance capabilities for each mounted equipment, and interviews with operators and maintenance practitioners confirmed the limitations of outsourcing maintenance and the need to apply PBL. In order to analyze the effect of PBL application, the measure of effectiveness and measure of performance were selected based on the opinions of LSF-II operation/maintenance practitioners and PBL experts and the practical experience of this researcher. A survey was conducted on operation/maintenance practitioners and professional personnel. Based on the survey results, the effect of applying PBL was analyzed using the AHP technique, and an efficient PBL application plan was proposed for LSF-II.

Recently, there has been an increasing attempt to replace defect detection inspections in the manufacturing industry using deep learning techniques. However, obtaining substantial high-quality labeled data to enhance the performance of deep learning models entails economic and temporal constraints. As a solution for this problem, semi-supervised learning, using a limited amount of labeled data, has been gaining traction. This study assesses the effectiveness of semi-supervised learning in the defect detection process of manufacturing using the MixMatch algorithm. The MixMatch algorithm incorporates three dominant paradigms in the semi-supervised field: Consistency regularization, Entropy minimization, and Generic regularization. The performance of semi-supervised learning based on the MixMatch algorithm was compared with that of supervised learning using defect image data from the metal casting process. For the experiments, the ratio of labeled data was adjusted to 5%, 10%, 25%, and 50% of the total data. At a labeled data ratio of 5%, semi-supervised learning achieved a classification accuracy of 90.19%, outperforming supervised learning by approximately 22%p. At a 10% ratio, it surpassed supervised learning by around 8%p, achieving a 92.89% accuracy. These results demonstrate that semi-supervised learning can achieve significant outcomes even with a very limited amount of labeled data, suggesting its invaluable application in real-world research and industrial settings where labeled data is limited.

Mid-sized manufacturing companies, which account for 0.7%(5,480 companies), 13.8%(1.169 million persons) of total employment, and 15.7% of total sales, have recently experienced a lot of difficulties in management activities due to the impact of COVID-19, the U.S.-China trade war, and the collapse of global supply chains. To overcome this, revitalization of quality management activities to strengthen corporate competitiveness is emerging as an urgent task. In order for these quality management activities to achieve their intended purpose, the positive leadership of corporate managers is very important above all else. There have been many studies related to positive leadership, but most have focused on charismatic leadership and transformational leadership centered on large companies or small and medium-sized enterprises. Therefore, this study aims to present ways to strengthen the leadership of managers by empirically analyzing how the positive leadership of managers of mid-sized manufacturing companies, which was relatively under-researched, affects quality management activities and Business performance(Balanced Score Card; BSC).

The computer system validation consulting industry is growing as domestic GMP companies' overseas exports or advancements increase, and computer system validation has been mandatory in Korea since the 2010s, but domestic CSV consulting companies are small in size and have a short history, revealing many shortcomings in terms of service quality and customer satisfaction when conducting consulting. Research related to consulting has been mainly focused on management consulting and IT consulting, and research related to computer system validation is very insufficient. This study confirmed the effect of consultant competency and service quality on consulting performance, customer satisfaction, and intention to renew contract when performing computer system validation through empirical research on food, pharmaceutical, cosmetics, and medical device companies, which are representative companies in the GMP industry. As a result, it was confirmed that consultant competency and service quality had a significant effect on consulting performance, customer satisfaction, and intention to renew contract. In addition, it was confirmed that the reputation and expertise of consulting companies had a moderating effect on the relationship between consultant competency and consulting performance.

본 연구의 목적은 피부미용 종사자의 그릿이 자기효능감과 직무성과에 미치는 영향을 관계 에서 자기관리의 매개효과를 실증적으로 분석하는데 있다. 본 연구의 연구참여자는 서울·경기 스킨케어 샵과 병원 종사자 344명을 대상으로 구조화된 설문지를 통하여 자료를 수집하였다. 수집된 자료는 SPSS 와 AMOS 26.0 통계 프로그램을 이용하여 기술통계, 확인적 요인분석, 상관관계, 구조방정식모델, bootstrapping기법을 이용한 매개효과 분석을 통하여 자료를 분석하였다. 일련의 연구절차를 통하여 도 출된 결론은 다음과 같다. 첫째, 피부미용 종사자의 그릿은 자기관리, 자기효능감, 직무성과에 유의미한 정의(+)영향 관계를 나타내 었다. 둘째, 피부미용 종사자의 자기관리는 자기효능감과 직무성과에 유의미한 정의(+) 영향 관계를 나 타내었다. 셋째, 피부미용 종사자의 그릿과 직무성과와의 관계에서 자기관는 유의미한 매개효과가 있는 것으로 나타났다. 따라서 뷰티 산업 종사자들의 그릿 함양을 통해 자기관리, 자기효능감 및 직무성과를 높일 수 있는 인적관리와 교육 프로그램의 적용이 절실히 필요하다고 판단된다..

이 연구는 중국 대학 태권도 지도자의 이미지가 선수의 그릿, 심리상태와 경기수행력에 미치는 영향을 연구하여 향후 중국 대학 태권도의 질적 발전을 위해 우수한 지도자양성 기초 자료를 제공하는 데 그 목적을 두고 있다. 이 연구를 위해 중국 허난성 대학교에 있는 선수를 대상으로 모집단을 선정하였으며, 편의표본추출법을 통해 표본을 추출하였다. 회수된 380부의 설문지 중, 응답이 불성실하고 또는 누락된 문 항이 있는 15부를 제외하여 총 365부를 결과처리에 사용하였다. 수집된 자료는 SPSS 23.0 프로그램을 사 용하여 빈도분석, 상관관계분석, 신뢰도분석, 탐색적 요인분석 및 다중회귀분석을 통해 실시했다. 이 연구 의 결과는 다음과 같다. 첫째, 지도자 이미지의 하위요인인 지도자의 사회활동과 직업의식, 자질, 업무, 역 할은 태권도 선수의 그릿에 유의한 영향을 미치는 것으로 나타났다. 둘째, 지도자 이미지의 하위요인인 지 도자의 사회활동과 직업의식, 자질, 태도, 업무, 역할은 태권도 선수의 심리상태에 유의한 영향을 미치는 것으로 나타났다. 셋째, 지도자 이미지의 하위요인인 지도자의 사회활동과 직업의식, 자질, 태도는 태권도 선수의 경기수행력에 유의한 영향을 미치는 것으로 나타났다.

본 연구는 8주간의 고강도 동계 훈련 시 L-아르기닌 섭취가 남자 대학 태권도 겨루기 선수의 경기수행능력, 젖산, 젖산탈수소효소 및 암모니아에 미치는 영향을 구명하기 위해 L-아르기닌 섭취군 (n=14), 위약군(n=14)으로 구분하여 실시하였다. L-아르기닌 섭취군은 일일 아침 1 g, 점심 1 g, 저녁 1 g으로 총 3 g 섭취하였고 위약군은 말토덱스트린을 동일한 방법으로 섭취하였다. 8주간의 동계 훈련 프로그램은 70-90%HRR로 실시하였다. 측정된 자료의 L-아르기닌 섭취군과 위약군 간의 그룹 및 시기 간 상 호작용 효과는 two-way repeated measures ANOVA, 그룹 내 시기 간 차이는 paired t-test를 사용하였으 며, 그룹 간 차이는 independent t-test를 사용하여 분석하였다. 그 결과 TAAA (Taekwondo-specific aerobic anaerobic agility) test를 통한 경기수행능력 중 평균 발차기 수에서 그룹×시기 간 상호작용 효과 가 나타났으며 그룹 간 주효과가 나타났다(p<.05). 또한, 발차기 피로지수에서 그룹×시기 간 상호작용 효 과가 나타났다(p<.05). 한편, 젖산에서는 시기 간 주효과가 나타났으며(p<.05) 젖산탈수소효소에서 상호작 용 효과 및 시기 간 주효과 나타났다(p<.05). 암모니아의 경우 그룹×시기 간 상호작용 효과가 나타났다 (p<.05). 이러한 결과는 남자 대학 태권도 겨루기 선수의 고강도 훈련 후 피로에 쉽게 노출되는 선수들에게 L-아르기닌 섭취로 인해 체내 피로 유발 물질들을 신속하게 제거하는 데 긍정적인 역할을 할 수 있다고 사료된다. 따라서 고강도 엘리트 태권도 겨루기 운동선수의 경기수행능력 향상과 피로 회복 방법으로 L- 아르기닌 섭취를 권장한다.

본 연구의 목적은 뷰티 서비스 종사자들의 행동 루틴이 서비스수행 및 업무성과에 미치는 영 향 관계에서 자기효능감의 매개역할을 분석하고자 하였다. 연구대상자는 서울·경기 소재 뷰티 소비자 311명이며, 구조화된 설문지를 이용하여 자료를 수집하고 분석되었다. 자료 분석은 기술통계, 확인적 요 인분석, 상관관계분석, 구조방정식모델 및 bootstrapping 기법을 이용한 매개효과 분석을 실시하였다. 일 련의 연구절차를 통하여 도출된 결론은 다음과 같다. 첫째, 뷰티 서비스 종사자의 행동 루틴은 자기효능 감, 서비스수행, 업무성과에 모두 통계적 유의한 정적(+) 영향을 미치는 것으로 나타났다. 둘째, 뷰티 서 비스 종사자의 자기효능감은 서비스수행 및 업무성과에 통계적 유의한 정적(+) 영향을 미치는 것으로 나타났다. 셋째, 뷰티 서비스 종사자의 행동 루틴과 서비스수행 및 직무성과와의 관계에서 자기효능감의 부분 매개효과를 나타내었다.

In this study, a condensate drain valve was newly installed in the steam inlet pipe line of the soot blower to reduce the amount of condensate contained in the steam for the soot blower. When the economizer is inactive, the condensate drain valve on the soot blower steam inlet pipe line is always opened to drain the condensate. It is intended to reduce environmental pollution and improve economizer performance by reducing the water hammer that inevitably occurs in facilities using steam, and reducing the amount of condensate water generated during the shutdown of the soot blower and the release of soot containing condensate water into the atmosphere when removing soot.