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.

본 연구는 과학문화 활성화를 위한 효율적 정책 추진을 목적으로 인 천지역 과학문화의 특성을 파악하고 확산 정도를 파악하고자 한다. 이를 위해 네이버 지도 내 등록된 인천지역의 구조물을 탐색하고 인천광역시 홈페이지 및 인천지역 8개의 구, 2개의 군을 대상으로 구·군청 공식 홈 페이지를 활용하여 인천 8구·2군의 지역별 과학문화 확산에 기여할 수 있는 인프라를 분석하였다. 그 결과 인천지역 8구·2군의 인프라 유형은 역사적 가치를 담은 박물관이 가장 많았으며 체험장, 연구소, 공단에서 조성한 공간, 교육센터, 과학관, 공원, 기업에서 운영하는 공간 순으로 구 성되었다. 특히, 기업에서 운영하는 과학문화 공간이 가장 적은 실정이며 이러한 인프라는 서구, 중구, 연수구에만 집중된 것으로 나타났으며, 인 천지역의 구･군별 과학문화 인프라의 격차가 있음을 확인하였다. 하지만, 인천은 오랜 역사를 가지고 발전해 왔기에 지역의 고고학적 자료, 역사적 유물, 예술품 등의 역사 문화에 관한 인프라가 구축되어 있으며 지리적으 로도 서해와 인접하고 한강의 하류에 위치하여 168개의 크고 작은 섬과 한강과 서해로 유입되는 작은 하천, 산 등 인천만의 특화된 풍부한 자연 환경을 가지고 있다. 따라서, 인천의 다양한 문화적 또는 지리적 특성의 자원을 체계적으로 구분하고 연계함으로써 인천광역시만의 특화된 과학 문화 인프라 자원을 활용하고 과학문화 향유의 기회를 제공할 수 있을 것으로 사료 된다.

In this study, the characteristics and taste components of six different oyster mushroom cultivars (Gonji-7ho, Santari, Baekseon, Chunchu, Suhan, and Heuktari) were analyzed and compared. The Heuktari mushroom pileus had the lowest brightness index (32.8) and remained dark (brightness index: 30.5) even after blanching. The moisture content of the mushrooms was approximately 90%. The salinity and sugar contents were highest in Heuktari (5.7% and 7.1%, respectively). Gonji -7ho had the highest contraction rates, with a length contraction rate of 16.4% and thickness contraction rate of 23.9%. The total amino acid content was highest in Heuktari (537.8 mg/100 g), but the glutamine content contributing to umami taste was highest in Santari (59.4 mg/100 g) and the aspartic acid content was highest in Baekseon (33.1 mg/100 g). Among the 5?-nucleotide components, guanosine monophosphate, which enhances umami taste, was highest in Baekseon (0.7 mg/g). Baekseon was also calculated to have the highest umami taste concentration based on amino acid and nucleic acid contents (12.7 g/100 g). The results of this study serve as valuable basic data on the physicochemical characteristics of oyster mushroom cultivars grown in Korea.

Seismic fragility curves play a crucial role in assessing potential seismic losses and predicting structural damage caused by earthquakes. This study compares non-sampling-based methods of seismic fragility curve derivation, particularly the probabilistic seismic demand model (PSDM) and finite element reliability analysis (FERA), both of which require employing sophisticated finite element analysis to evaluate and predict structural damage caused by earthquakes. In this study, a three-dimensional finite element model of API 5L X65, a buried gas pipeline widely used in Korea, is constructed to derive seismic fragility curves. Its seismic vulnerability is assessed using nonlinear time-history analysis. PSDM and a FERA are employed to derive seismic fragility curves for comparison purposes, and the results are verified through a comparison with those from the Monte Carlo Simulation (MCS). It is observed that the fragility curves obtained from PSDM are relatively conservative, which is attributed to the assumption introduced to consider the uncertainty factors. In addition, this study provides a comprehensive comparison of seismic fragility curve derivation methods based on sophisticated finite element analysis, which may contribute to developing more accurate and efficient seismic fragility analysis.

Protein can be provided by cultivating various microbes, which contain more than 30% protein content by cell dry weight. This study compared intracellular protein concentrations of various wild-type yeasts from different sources to select the best yeast strain with high protein concentration. Among them, Saccharomyces cerevisiae KCCM 34709, used for molasses fermentation, exhibited 4.1-fold higher protein concentration than a laboratory yeast strain, S. cerevisiae D452-2. In this study, an approach consisting of random mutagenesis coupled with the Bradford protein assay-based screening method was applied to enhance the S. cerevisiae KCCM 34709 protein content. Among 1,000 mutants, the #180 mutant strain produced 5,041±519 mg/L total amino acid in 48 h, which was 31% higher than the parental S. cerevisiae KCCM 34709 strain. These results demonstrate that the #180 mutant strain can be an attractive cell factory for animal-free protein production.

최근 4차산업과 급격한 디지털화, 세계 경제성장률의 하락 등으로 노 동시장은 급격하게 변화하고 있으며 이로 인해 청년 실업률은 매우 높은 상태이다. 또한, 인구구조와 산업구조의 재편에 따라 청년층의 취업여건 은 나아지지 않고, 기업은 신입보다 경험을 가진 인력을 채용하고 있다. 이에 따라 본 연구는 해외 주요국(독일, 덴마크, 영국, 프랑스, 호주)의 청년 일경험 지원정책에 대해 살펴보고 일경험 프로그램을 종합적으로 비교함으로써 우리나라의 청년 일경험 정책에 관한 시사점을 도출하였 다. 분석결과 주요국의 청년 일경험 프로그램은 목적을 달리하여 운영되 고 있고, 대상자의 근로능력 수준에 따라 적합한 프로그램을 연계하고 있다. 또한, 단계별 프로그램과 대상에 따른 프로그램으로 구성되어 있고 운영은 직접 운영과 민간위탁 방식으로 구분되었다. 이러한 비교분석 결 과를 바탕으로 정책적 시사점을 제시하였다.

FT-IR, GC/MS, and ATR-FT-IR analyses were performed to confirm the physicochemical characteristics of saw palmetto fruit (SPF) extract. FT-IR analysis of the standard product showed that the band corresponding to the carbonyl bond of free fatty acid was stronger than the band of acyl-glyceride. Sample E was identified as having the same trend as the standard sample. Fatty acid composition analysis revealed that the main fatty acids in the standard sample were lauric acid and oleic acid. The content of lauric acid ranged from approximately 30% to 38% in samples B, C, D, and E, while the content of oleic acid ranged from approximately 29% to 34%. The GC/MS analysis confirmed that the standard SPF extract consisted of fatty acids and fatty acid ethyl esters. Sample E demonstrated a similar pattern to the standard samples in terms of oleic acid, lauric acid, and fatty acid esters. ATR-FT-IR analysis indicated that only sample E was predicted to contain 100% saw palmetto extract. Therefore, these study findings can be considered fundamental data for analyzing the physicochemical characteristics of the composition of SPF extract.

본 연구에서는 실리카 복합막 기반 고분자 전해질막을 5단 연료전지 스택에 적용하여 성능 평가를 수행하였다. 이를 통하여, 개별 구성 요소의 성능도 중요하지만, 전체적인 관점에서 공급되는 연료의 유량이 스택 성능에 중요한 역할을 하며, 특히 수소의 유량에 크게 의존한다는 사실이 확인하였다. 산소의 유량을 증가시켜도 성능의 변화는 미미한 반면, 수소 의 유량을 증가시키면 성능이 향상되는 것을 확인하였다. 그러나 수소의 유량 증가는 수소와 산소 유량 비율의 불균형을 초 래하여 장기적으로는 스택 성능과 내구성을 저하시키는 문제가 관찰되었다. 이러한 현상을 스택 구성 요소 및 개별 단위 셀 에서도 관찰할 수 있었으며, 따라서 스택 운전 시 각 구성 요소의 성능을 최적화하는 것 외에도 균일한 유량 제어를 위해 유 로 설계 및 운전 조건을 최적화하는 것이 중요하다는 것을 알 수 있었다. 마지막으로 실리카 복합막은 최대 출력 기준 25 W 이상의 성능을 나타내어 실제 연료전지 시스템에 적용하기에 충분한 성능을 갖춘 것으로 판단된다.

Paddy fields provide important habitats for biodiversity conservation within the agricultural ecosystem. Their importance is gradually increasing as their ecological value is better understood. Benthic macroinvertebrates dominate paddy fields. They play an essential role in maintaining the biodiversity of paddy ecosystems. This study aimed to analyze characteristics of benthic macroinvertebrate communities and main environmental factors affecting the distribution of golden apple snails (Pomacea canaliculata). Results showed that the diversity index (H ′) of the benthic macroinvertebrate community was the highest at the Sangju site (St. 12) but the lowest at the Sancheong site (St. 18). Total Dissolved Solids (TDS), salinity, and Electrical Conductivity (EC) values were the highest in Gimhae and Yeongam based on Canonical Correspondence Analysis (CCA). Numbers of P. canaliculata (m-2) were relatively low in Gunsan and Iksan where water temperatures were high. Therefore, changes in geographical characteristics and environmental factors might affect the distribution of P. canaliculata and characteristics of benthic macroinvertebrate communities. Results of this study can be used as primary data for biodiversity conservation and ecosystem service evaluation in agroecosystems.