This study aimed to grow single crystals with low dislocation density using a heat exchange method using room temperature water, and investigated the effect of the structure of the heat exchanger under the crucible on the defects and dislocation density of the single crystals and the shape of the solid-liquid interface of the crystals, and obtained the following conclusions. The dislocation density of sapphire single crystal grown at 2,200℃ for 30 min and a growth rate of 0.2℃/min was 0.92x103pcs/㎠. Mo guard was used to stabilize the solid-liquid interface grown from seeds, and sapphire single crystals with a diameter of 130㎜ and a height of 75㎜ were grown.

본 연구에서는 토지매수 청구 제도에 의한 국립공원 내 사유지 매수 현황을 분석하여, 토지매수 청구 제도의 유용성과 한계, 정책 시사점을 도출하였다. 토지매수 청구 제도가 도입된 2006년부터 2021년까지 국가가 매수한 사유지 데이터를 활용하여, 토지 소유자의 매수 청구 결정에 영향을 미치는 요인들을 로지스틱 회귀분석을 통해 분석하였다. 분석 결과, 사유지의 지목이 임야이고, 사유지 면적 중 공원자연보존지구 면적이 높으며, 공원 경계까지 거리가 멀고, 단위면적당 공시지가가 낮은 사유지가 매수 청구에 의해 매수될 확률이 높았다. 이 결과는 토지 소유자 관점에서 보면 재산권 행사가 어려운 사유지일수록 매수 청구될 확률이 높다는 뜻이고, 공원 관리자의 관점에서 보면 보전 가치가 높은 사유지가 매수 청구될 확률이 높다는 의미이다. 즉, 토지매수 청구 제도를 활용하여 사유지 매수를 진행해도 보전 가치가 높은 토지를 매수할 수 있어, 높은 자연환경 보전 효과를 기대할 수 있다. 로지스틱 회귀모형은 또한 북한산국립 공원 내 사유지 중 401㎡의 사유지가 향후 매수 청구될 확률이 높을 것으로 예측하였다. 토지매수 청구 제도는 국립공원 내 토지 소유자의 민원 해소에 효과적인 제도임에도 현재 활용도가 매우 낮은데, 본 연구에서는 실증 분석 결과를 바탕으로 제도의 활용도를 높일 수 있는 정책 방안을 제시하였다.

Microplastics and nanoplastics (NMPs) are considered one of hazardous contaminants in marine ecosystems due to their toxic effects, such as reproduction disorder and oxidative stress, on marine organisms. Although water temperature is rising due to global climate change, little information on the toxicological interaction between NMPs and temperature is available. Therefore, in this study, we confirmed the toxicity of NMPs (polystyrene [PS] beads; 0.05- and 6-μm) on brackish water fleas (Diaphanosoma celebensis) depending on increased temperature (30°C and 35°C) at individual and molecular levels. In the chronic toxicity test, the group exposed to high temperatures showed an earlier first reproduction time compared to the normal temperatures group, but it was delayed by co-exposure to NMPs at 35°C. Notably, the total reproduction decreased significantly only after 0.05-μm PS beads exposure at 30°C. Interaction analysis showed that first reproduction time, modulation of the antioxidantrelated gene (GSTS1), heat shock gene (Hsp70), and ecdysteroid pathway-related genes (EcR_A, EcR_B, and CYP314A1) were closely related to temperature and PS beads size. These results indicate that microplastics have size-dependent toxicity, and their toxicity can be enhanced at high temperatures. In addition, higher temperatures and PS beads exposure may have negative effects on reproduction. This study suggests that various factors such as water temperature should be considered when evaluating the toxicity of microplastics in marine ecosystems, and provides an understanding of the complex toxic interaction between water temperature and microplastics for marine zooplankton.

In Korea, as part of the Green New Deal project toward a carbon-neutral society, it is necessary to build a climate-resilient urban environment to green the city, space, and living infrastructure. To this end, SWMM-ING was improved and the model was modified to analyze the carbon reduction effect. In addition, I plan to select target watersheds where urbanization is rapidly progressing and evaluate runoff, non-point pollution, and carbon reduction effects to conduct cost estimation and optimal design review for domestic rainwater circulation green infrastructure. In this study, green infrastructure facilities were selected using SWMM-ING. Various scenarios were presented considering the surface area and annual cost of each green infrastructure facility, and The results show that the scenario derived through the APL2 method was selected as the optimal scenario. In this optimal scenario, a total facility area of 190,517.5 m2 was applied to 7 out of 30 subwatersheds to achieve the target reduction. The target reduction amount was calculated a 23.50 % reduction in runoff and a 26.99 % reduction in pollutant load. Additionally, the annual carbon absorption was analyzed and found to be 385,521 kg/year. I aim to achieve additional carbon reduction effects by achieving the goal of reducing runoff and non-point pollution sources and analyzing annual carbon absorption. Moreover, considering the scale-up of these interventions across the basin, it is believed that an objective assessment of economic viability can be conducted.

플라스틱은 전세계적으로 사용량이 증가함에 따라 해양 환경으로 유입되는 플라스틱 쓰레기의 양도 꾸준히 증가하고 있으며, 미세플라스틱은 해양 생물에 의해 섭취되어 소화관에 축적됨에 따라 성장과 생식에 유해한 영향을 미친다. Cytochrome P450 (CYP)는 환경 오염물질을 대사하 는 해독효소로 알려져 있으나 지각류에서는 그 기능에 대해서는 잘 알려져 있지 않다. 본 연 구에서는 기수산 물벼룩 Diaphanosoma celebensis에서 clan 2, 3, 4에 각각 속하는 CYP 유전자 9종(clan 2: CYP370A4, CYP370C5; clan 3: CYP350A1, CYP350C5, CYP361A1; clan 4: CYP4AN-like, CYP4AP2, CYP4AP3, CYP4C33-like1)의 서열에 대해 진화적으로 보존된 서열의 유사도를 분석 하고 계통분석을 실시하였다. 또한 3종류의 서로 다른 크기의 polystyrene beads (0.05-, 0.5-, 6-μm PS beads; 0.1, 1, and 10 mg/L)에 48시간 노출된 기수산 물벼룩에서 이들 9종의 CYP 유 전자의 발현을 real time reverse transcription polymerase chain reaction (RT-PCR)로 분석하였 다. 결과적으로 기수산 물벼룩 CYP 유전자는 모두 진화적으로 보존된 motif를 가지고 있으며 계통분석 결과 각각 clan 2, 3, 4에 속하는 것으로 확인되었다. 이는 기능적으로 보존되어 있음 을 의미한다. CYP 유전자 중 clan 2에 속하는 CYP370C5와 clan 3에 속하는 CYP360A1, 그리고 clan 4에서는 CYP4C122 유전자의 발현이 0.05-μm PS beads에 노출되었을 때 유의하게 증가 하는 양상을 보였으며, 이는 이들 유전자가 PS 대사에 관여한다는 것을 의미한다. 본 연구는 미세플라스틱이 해양 무척추 동물에 미치는 생물 영향을 분자적 수준에서 이해하는데 도움이 될 것이다.

This study aims to assess the seismic performance of retrofitted reinforced concrete columns using a Replaceable Steel Brace (RSB) system, subjected to combined axial, lateral, and torsional loadings. Through experimental testing, one non-retrofitted concrete column specimen and two retrofitted specimens with variable sliding slot lengths were subjected to eccentric lateral loads to simulate realistic seismic loading. The retrofitted specimens with RSBs exhibited enhanced resistance against shear cracking, effective torsional resistance, and demonstrated the feasibility of easy replacement. The RSB system substantially improved seismic performance, achieving approximately 1.7 times higher load capacity and 3.5 times greater energy dissipation compared to non-retrofitted column, thus validating its efficacy under combined loading conditions.

The purpose of this study is to experimentally analyze the seismic performance of column with RSB (Replaceable Steel Brace), a steel brace system with slot length as a variable. To evaluate the seismic performance of the RSB, three specimens were manufactured and subjected to cyclic loading tests. The length of the sliding slots were considered to be 5 mm and 10mm to enable the brace to resist the load from the initiation of flexural crack and shear crack. As a result of the test, the specimen reinforced with the RSB showed improved maximun load and effective stiffness, and energy dissipation capacity compared to the non-reinforced specimens. The specimens with 5mm sliding slot showed little difference in test result compared to the specimen with a 10mm sliding slot, indicating that the length of sliding slot has little influence on the effectiveness of RSB.

Conventional aquaculture faces declining productivity, shifting to recirculating aquaculture system (RAS), known for minimizing water usage and maintaining consistent water temperatures for year-round fish growth. Rainbow trout (Oncorhynchus mykiss), a globally important cold-water species and the third most farmed fish in inland waters of Korea, valued for its fecundity and rapid growth. Dissolved oxygen, an important environmental factor affecting fish production and economics, highlights the need for smart aquaculture practices. Since 2018, the rise of intelligent aquaculture platforms, incorporating information and communications technology (ICT), emphasizes the essential role of RAS implementation. This eight-week study aimed to determine the optimal dissolved oxygen concentration for rainbow trout in RAS, utilizing a device for continuous monitoring, control and record. Dissolved oxygen concentrations were set at 5-6 mg/L, 9-10 mg/L, 14-15 mg/L and 17-18 mg/L. The growth rate significantly decreased at 5-6 mg/L, with no significant differences in other experimental groups. In hematological analysis, growth hormone (GH) was significantly highest at 5-6 mg/L, followed by 9-10 mg/L while Insulin-like growth factor-1 (IGF-1) was significantly lowest at 5-6 mg/L. In conclusion, the optimal dissolved oxygen concentration for rainbow trout in RAS is approximately 9-10 mg/L. Higher concentrations do not contribute to further growth or profitability.

In this paper, among the various facilities used in marine farming, young bivalves of the Mytilus galloprovincialis of marine farming was placed on the deck of the fishing vessel to evaluate the environment conditions and drive shaft movement by rolling affecting the separator for the young bivalves and a clean process. There were a few studies on stress analysis of development facilities because it was difficult to access the fishing site due to the use of imported equipment and the lack of development of domestic equipment. In this study, stress analysis of the fixed part of separator for young bivalves and its adjacent part was performed on various phases when the vessel was tilted by rolling using the finite element method. In addition, the structural safety of the internal blade under the driving conditions according to the movement of the drive shaft by the hydraulic motor was confirmed through structural analysis. As a result, the connection part between the deck and the separator by rolling was confirmed to have higher stress than that of other parts due to stress concentration. In addition, it was confirmed that the maximum stress occurred on the connection part between blades. Even though the safety of the separator for marine farming was confirmed by structural analysis, it is necessary to comprehensively consider the age of vessels, the material of the deck, and the corrosion of the deck.

In this study, a vibrating nozzle using the waste vibration energy of the compressor body was installed in the suction flow path to improve the efficiency of the compressor through the pre-compression. To this end, the behavior of the suction valve according to the vibrating nozzle and the mass flow rate of the refrigerant entering the compression chamber were numerically analyzed. The results showed that the mass flow rate increased proportionally as the angle of the vibration nozzle increased. Among the profile shapes of the vibration nozzle, the concave or straight shape showed the highest mass flow rate. Considering the ease of machining, the straight shape is more favorable. On the other hand, as the operating frequency and stroke of the vibration nozzle increased, the mass flow rate also increased proportionally. It can be seen that the largest nozzle angle, operating frequency, and stroke are favorable for pre-compression unless the suction flow is restricted.. In the future, it is necessary to apply the vibrating nozzle system to an actual compressor model to experimentally check the compressor's cooling power, compression work and EER.

This study aims to help companies with efficient investment and marketing strategies by empirically verifying the impact on satisfaction and purchase intention for artificial intelligence-based digital technology supported shopping assistants introduced in e-commerce. Frequency, factor, SEM, and multiple group analysises were conducted using SPSS 26.0 and Amos 26.0. As a result, first, motivated consumer innovativeness elements of AI shopping assistant were derived into a total of four categories: functional, hedonic, rational, and reliable. Second, in the order of hedonic and rational, satisfaction with the AI shopping assistant was significantly affected, and in the order of rational and functional, purchase intention was significantly affected. The satisfaction with the AI shopping assistant did not affect the purchase intention. Third, in the case of hedonic, the AI-preferred group had a more significant effect on satisfaction than the human-preferred group, and in the case of rational, there was no difference by group in purchase intention. Thus, it was found that consumers prefer AI shopping helpers for e-commerce because they can shop reasonably and are functionally convenient. Therefore, when introducing AI shopping assistants, it is essential to include content that can compare and analyze fundamental information, such as product prices, as well as search functions and payment system compatibility that facilitate shopping.

In the global manufacturing industry, digital transformation is emerging as an important issue for companies to improve productivity and strengthen industrial competitiveness. The government and shipbuilding companies drive research and development to attain advanced technologies through digital transformation for shipbuilding & offshore plants, one of Korea's representative manufacturing industries. Therefore, the digital transformation of the shipbuilding & offshore plant industry was defined using an input-output analysis model, and the economic interrelationships of industries linked to the digital transformation of the shipbuilding & offshore plant industry were analyzed. According to the analysis, the shipbuilding & offshore plant industry ranks second among all 34 industries regarding the forward linkage effect. The backward linkage effect was ranked 27th, making it a mid-demand industry with a robust forward linkage effect. In addition, the production-induced effect was 0.455, the value-added-induced effect was 0.174, and the employment-induced effect was 1.779 people per billion won. The contribution of this study is that it will provide the basis for establishing policies necessary to strengthen the competitiveness of the shipbuilding & offshore plant industry. Also, it will help analyze the economic effects of digital transformation in other manufacturing industries.