• Title/Summary/Keyword: Response

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Future hydrological changes in Jeju Island based on CMIP6 climate change scenarios (CMIP6 기후변화 시나리오에 따른 제주도 지역의 미래 수문변화 전망)

  • Kim, Chul-Gyum;Cho, Jaepil;Lee, Jeong Eun;Chang, Sunwoo
    • Journal of Korea Water Resources Association
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    • v.56 no.11
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    • pp.737-749
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    • 2023
  • In this study, we analyzed the hydrological impacts of future climate change on Jeju Island using SSP-based climate change scenarios from 18 climate models and watershed modeling (SWAT-K). Despite discrepancies among climate models, we generally observed an increase in evapotranspiration due to rising future temperatures. Furthermore, a significant increase in runoff and recharge was noted due to increased precipitation. These increasing trends were particularly pronounced in the SSP5-8.5 scenario, and differences among GCM models became more significant in the late 21 century. When compared to the historical period (1981-2010), the projected changes for the far-future period (2071-2100) in the SSP5-8.5 scenario showed a 21.4% increase in precipitation, a 19.2% increase in evapotranspiration, a 40.9% increase in runoff, and a 16.6% increase in recharge on an annual average basis. On a monthly basis in the SSP5-8.5 scenario, precipitation was expected to increase by 24.5% in September, evapotranspiration by 34.1% in April, runoff by 58.1% in October, and recharge by 33.8% in September. To further assess projections based on extreme climate scenarios, we selected two models, CanESM5 and ACCESS-ESM1-5, which represented the maximum and minimum future precipitation forecasts, and compared the hydrological changes in the future scenarios. The results indicated that runoff and recharge rates were relatively higher in the CanESM5 model with the highest precipitation forecast, while evapotranspiration rates were higher in the ACCESS-ESM1-5 model with the lowest precipitation forecast. Based on the climate change scenarios used in this study, the overall available water resources on Jeju Island are more likely to increase. However, since results vary by season and region depending on the climate model and scenario, it is considered necessary to conduct a comprehensive analysis and develop response measures using various scenarios.

The study of heavy rain warning in Gangwon State using threshold rainfall (침수유발 강우량을 이용한 강원특별자치도 호우특보 기준에 관한 연구)

  • Lee, Hyeonjia;Kang, Donghob;Lee, Iksangc;Kim, Byungsikd
    • Journal of Korea Water Resources Association
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    • v.56 no.11
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    • pp.751-764
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    • 2023
  • Gangwon State is centered on the Taebaek Mountains with very different climate characteristics depending on the region, and localized heavy rainfall is a frequent occurrence. Heavy rain disasters have a short duration and high spatial and temporal variability, causing many casualties and property damage. In the last 10 years (2012~2021), the number of heavy rain disasters in Gangwon State was 28, with an average cost of 45.6 billion won. To reduce heavy rain disasters, it is necessary to establish a disaster management plan at the local level. In particular, the current criteria for heavy rain warnings are uniform and do not consider local characteristics. Therefore, this study aims to propose a heavy rainfall warning criteria that considers the threshold rainfall for the advisory areas located in Gangwon State. As a result of analyzing the representative value of threshold rainfall by advisory area, the Mean value was similar to the criteria for issuing a heavy rain warning, and it was selected as the criteria for a heavy rain warning in this study. The rainfall events of Typhoon Mitag in 2019, Typhoons Maysak and Haishen in 2020, and Typhoon Khanun in 2023 were applied as rainfall events to review the criteria for heavy rainfall warnings, as a result of Hit Rate accuracy verification, this study reflects the actual warning well with 72% in Gangneung Plain and 98% in Wonju. The criteria for heavy rain warnings in this study are the same as the crisis warning stages (Attention, Caution, Alert, and Danger), which are considered to be possible for preemptive rain disaster response. The results of this study are expected to complement the uniform decision-making system for responding to heavy rain disasters in the future and can be used as a basis for heavy rain warnings that consider disaster risk by region.

Experimental Study on Energy Saving through FAN Airflow Control in the Generator Room of a 9200-ton Training Ship (9200톤급 실습선 발전기실 FAN 송풍유량 제어를 통한 선박에너지 절약에 관한 실험적 연구)

  • Moon-seok Choi;Chang-min Lee;Su-jeong Choe;Jae-jung Hur;Jae-Hyuk Choi
    • Journal of the Korean Society of Marine Environment & Safety
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    • v.29 no.6
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    • pp.697-703
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    • 2023
  • As a part of the global industrial efforts to reduce environmental pollution owing to air pollution, regulations have been established by the International Maritime Organization (IMO). The IMO has implemented various regulations such as EEXI, EEDI, and CII to reduce air pollution emissions from ships. They are also promoting measures to decrease the power consumption in ships, aiming to conserve energy. Most of the power used in ships is consumed by electric motors. Among the motors installed on ships, the engine room blower that takes up a significant load, operates at a constant irrespective of demand. Therefore, energy savings can be expected through frequency control. In this study, we demonstrated the efficacy of energy savings by controlling the frequency of the electric motor of the generator blower that supplies combustion air to the generator's turbocharger. The system was modeled based on the output data of the turboharger outlet temperature in response to the blower frequency inpu. A PI control system was established to control the frequency with the target being the turbocharger outlet temperature. By maintaining the turbocharger design standard outlet temperature and controlling the blower frequency, we achieved an annual energy saving of 15,552kW in power consumption. The effectiveness of energy savings through frequency control of blower fans was verified during the summer (April to September) and winter (March to October) periods. Based on this, we achieved annual fuel cost savings of 6,091 thousand won and reduction of 8.5 tons of carbon dioxide, 2.4 kg of SOx, and 7.8 kg of NOx air pollutants on the training ship.

Effect of Varying Excessive Air Ratios on Nitrogen Oxides and Fuel Consumption Rate during Warm-up in a 2-L Hydrogen Direct Injection Spark Ignition Engine (2 L급 수소 직접분사 전기점화 엔진의 워밍업 시 공기과잉률에 따른 질소산화물 배출 및 연료 소모율에 대한 실험적 분석)

  • Jun Ha;Yongrae Kim;Cheolwoong Park;Young Choi;Jeongwoo Lee
    • Journal of the Korean Institute of Gas
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    • v.27 no.3
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    • pp.52-58
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    • 2023
  • With the increasing awareness of the importance of carbon neutrality in response to global climate change, the utilization of hydrogen as a carbon-free fuel source is also growing. Hydrogen is commonly used in fuel cells (FC), but it can also be utilized in internal combustion engines (ICE) that are based on combustion. Particularly, ICEs that already have established infrastructure for production and supply can greatly contribute to the expansion of hydrogen energy utilization when it becomes difficult to rely solely on fuel cells or expand their infrastructure. However, a disadvantage of utilizing hydrogen through combustion is the potential generation of nitrogen oxides (NOx), which are harmful emissions formed when nitrogen in the air reacts with oxygen at high temperatures. In particular, for the EURO-7 exhaust regulation, which includes cold start operation, efforts to reduce exhaust emissions during the warm-up process are required. Therefore, in this study, the characteristics of nitrogen oxides and fuel consumption were investigated during the warm-up process of cooling water from room temperature to 88℃ using a 2-liter direct injection spark ignition (SI) engine fueled with hydrogen. One advantage of hydrogen, compared to conventional fuels like gasoline, natural gas, and liquefied petroleum gas (LPG), is its wide flammable range, which allows for sparser control of the excessive air ratio. In this study, the excessive air ratio was varied as 1.6/1.8/2.0 during the warm-up process, and the results were analyzed. The experimental results show that as the excessive air ratio becomes sparser during warm-up, the emission of nitrogen oxides per unit time decreases, and the thermal efficiency relatively increases. However, as the time required to reach the final temperature becomes longer, the cumulative emissions and fuel consumption may worsen.

A Study on the Types and Characteristics of Tech Start-up Preparation of Middle-Aged Entrepreneurs (중장년 기술창업가의 창업 준비 유형 및 특성에 대한 연구)

  • Sungpyo, Hong;Minhee, Kim
    • Asia-Pacific Journal of Business Venturing and Entrepreneurship
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    • v.18 no.1
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    • pp.125-140
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    • 2023
  • Careful preparation for a start-up can lower the risk of failure and create a successful business model. However, there are still challenges for middle-aged entrepreneurs, as start-up services and policies are often not readily accessible or fully utilized. Despite active research on middle-aged start-ups, previous studies have not delved deeply into the demographics of start-up preparation and various preparation behaviors. In response to this, a study was conducted to identify which start-up support services middle-aged entrepreneurs use, and how start-up preparation can be classified based on this. Data from 324 middle-aged tech start-up owners, based in Seoul and who started their businesses within the past 7 years, was collected and analyzed. The results showed that middle-aged entrepreneurs had moderate start-up preparation, with the greatest focus on the preparation period and the least focus on start-up education. Latent Profile Analysis revealed three groups of start-up preparation types among middle-aged entrepreneurs: "Overall Tribal Type," "Lack of Start-up Education Type," and "Comprehensive Preparation Type." BCH was performed on start-up satisfaction, start-up competence, fear of failure, access to start-up services, and support needs for middle-aged entrepreneurs based on the preparation type. The results showed that "Overall Tribal Type" had statistically lower start-up satisfaction, competence, and service accessibility compared to the other groups. Meanwhile, "Comprehensive Preparation Type" had a statistically lower fear of failure than the other types. "Overall Tribal Type" also had lower accessibility to middle-aged start-up services. All types had a high recognition of the need for support for specialized middle-aged start-ups. The findings highlight the need for more comprehensive support for middle-aged entrepreneurs. This could include expanding support projects to enhance their level of preparation, providing customized support based on their level of preparation, and improving the visibility and accessibility of start-up support services for middle-aged individuals. Additionally, specialized education that addresses the characteristics of middle-aged individuals should be provided.

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The Impact of Entrepreneurs' Cognitive Biases on Business Opportunity Evaluation Depending on Social Networks (기업가의 인지편향이 사회적 네트워크에 따라 사업 기회 평가에 미치는 영향)

  • Jang, Hyo Shik;Yang, Dong Woo
    • Asia-Pacific Journal of Business Venturing and Entrepreneurship
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    • v.18 no.5
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    • pp.185-196
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    • 2023
  • This paper investigates the effects of entrepreneurs' cognitive biases on business opportunity evaluation, given their strong entrepreneurial spirit, which is characterized by innovation, proactivity, and risk-taking. When making decisions related to business activities, entrepreneurs typically make rational judgments based on their knowledge, experience, and the advice of external experts. However, in situations of extreme stress or when quick decisions are required, they often rely on heuristics based on their cognitive biases. In particular, we often see cases where entrepreneurs fail because they make decisions based on heuristics in the process of evaluating and selecting new business opportunities that are planned to guarantee the growth and sustainability of their companies. This study was conducted in response to the need for research to clarify the effects of entrepreneurs' cognitive biases on new business opportunity evaluation, given that the cognitive biases of entrepreneurs, which are formed by repeated successful experiences, can sometimes lead to business failure. Although there have been many studies on the effects of cognitive biases on entrepreneurship and opportunity evaluation among university students and general people who aspire to start a business, there have been few studies that have clarified the relationship between cognitive biases and social networks among entrepreneurs. In contrast to previous studies, this study conducted empirical surveys of entrepreneurs only, and also conducted research on the relationship with social networks. For the study, a survey was conducted using a parallel survey method using online mobile surveys and self-report questionnaires from 150 entrepreneurs of small and medium-sized enterprises. The results of the study showed that 'overconfidence' and 'illusion of control', among the independent variables of entrepreneurs' cognitive biases, had a statistically significant positive(+) effect on business opportunity evaluation. In addition, it was confirmed that the moderating variable, social network, moderates the effect of overconfidence on business opportunity evaluation. This study showed that entrepreneurs' cognitive biases play a role in the process of evaluating and selecting new business opportunities, and that social networks play a role in moderating the structural relationship between entrepreneurs' cognitive biases and business opportunity evaluation. This study is expected to be of great help not only to entrepreneurs, but also to entrepreneur education and policy making, by showing how entrepreneurs can use cognitive biases in a positive way and the influence of social networks.

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A Study of the Influence of Start-up New Product Preannouncing Information Attributes on Purchase Intention: Focused on UTAUT2 (프리어나운싱 정보속성이 스타트업 신제품 구매의도에 미치는 영향에 관한 연구: 확장된 통합기술수용이론(UTAUT2)을 중심으로)

  • Byung-chul Han;Jae-Hyun You
    • Asia-Pacific Journal of Business Venturing and Entrepreneurship
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    • v.18 no.5
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    • pp.1-16
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    • 2023
  • Due to imbalances in supply and demand within the labor market, start-ups have emerged as crucial players in the generation of high-quality employment opportunities, particularly in stagnant job markets. In response to this trend, governments are allocating substantial financial and human resources to initiatives that support start-up development. This has led to an increasing rate of engagement in start-up ventures across diverse age groups, not limited to younger individuals. Start-ups are enterprises focused on the commercialization of innovative ideas with the aim of achieving profitability in the marketplace. Research concerning the successful market integration of new products and the attainment of sustainable growth is pivotal. Such research is instrumental not only for the success of start-ups but also for realizing the broader social functions and contributions that these enterprises can offer. Previous research has often examined new product market-entry strategies, often referred to as new product marketing, particularly for large companies and SMEs. However, there is a gap in studies focusing on prototype marketing strategies specific to start-ups. Thus, this study aims to examine the impact of Pre-announcing marketing strategies on the market attention garnered by start-ups with low recognition and limited infrastructure, and how such attention contributes to their sustainable growth. Specifically, the study aims to uncover the causal relationship between information attributes like relevance, vividness, and novelty in building customer relationships, and their impact on purchase intentions influenced by performance expectations and hedonic motivations. In terms of Pre-announcing information attributes, relevance, vividness, and novelty positively influence performance expectations and hedonic motivations as outlined in the extended Unified Theory of Acceptance and Use of Technology (UTAUT2). These factors, in turn, positively impact the purchase intention for pre-announced new products from start-ups. These findings are expected to provide both theory and practical insights into the factors influencing market entry through the use of Pre-announcing marketing strategies for start-up new products.

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A study of growth factors, chondrogenic differentiation of mesenchymal stem cells and cell response by needle size differences in vitro (인간간엽줄기세포의 연골세포 분화 유도 성장인자 및 주사침 크기 차이에 따른 세포반응에 대한 in vitro 연구)

  • Jeongyun Park;Yu Jeong Hwang;Joseph Junesirk Choi;Jin Young Chon;Suk Won Lee
    • Journal of Dental Rehabilitation and Applied Science
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    • v.40 no.1
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    • pp.13-23
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    • 2024
  • Purpose: This aim of this study was to demonstrate growth factors that differentiate human mesenchymal stem cells into chondrocytes and to evaluate cell proliferation enhancement by needle size differences. Materials and Methods: Human mesenchymal stem cells were cultured in chondrogenic medium supplemented with BMP-2, BMP-4, BMP-6, BMP-7, BMP-13, FGF-2, FGF-18, IGF-1, TGF-β1, TGF-β2, TGF-β3 and without growth factors for 14, 21, and 28 days. Then, the expression levels of SOX-5, SOX-6, SOX-9 and FOXO1A were comparatively analyzed. Human mesenchymal stem cells were inoculated into culture dishes using 18, 21, and 26 gauge (G) needles, and cell proliferation was measured after 24, 48, and 72 hours, respectively. Results: In addition to the previously known FGF, IGF-1, and TGFβ1,the BMP family growth factors such as BMP-2, BMP-4, BMP-6, and BMP-7 increased the expression of chondrocyte differentiation genes SOX-5, SOX-6, SOX-9, and FOXO1A. At 48 hours, the 26G group, the smallest needle, showed significant cell proliferation improvement compared to the control group and the 18G group. At 72 hours, the 26G group, the smallest needle, showed significant increase in cell proliferation compared to the control group. Conclusion: Through this study, growth factors with the ability to induce chondrocyte differentiation of human mesenchymal stem cells were investigated, and cell proliferation changes by needle size differences were determined.

The Narrative Inquiry on the Identity and Role of Local Cultural Art Director as a Local Resident: Focus on C Region Crafts Biennale (지역민인 지역문화예술 감독의 정체성과 역할에 관한 내러티브 탐구 - C지역 공예비엔날레를 중심으로 -)

  • Sa, Yuntaek
    • Korean Association of Arts Management
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    • no.50
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    • pp.101-146
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    • 2019
  • After the enactment of the Local Culture Promotion Act in 2014, the government has been continuously trying to find the direction of the local culture that reflects the local life and conforms to the local people's emotions. In response to these efforts, the Organizing Committee for the C Region Biennale has uniquely formed the Biennale Artistic Director as a local artist who includes the historical, ecological and emotional characteristics of the C region. Therefore, I sought to explore the perception of the identity and role of the local cultural arts director through the narratives of the research participants who were appointed as the local residents of the C region and the director of the Craft Biennale. For the study, six local cultural arts directors were selected as research participants, and their identity as a local cultural arts director and its role were explored, focusing on their narratives. In this process, various types of data such as photographs, documents, in - depth interviews, and conference materials were collected and narrative was analyzed based on deterministic events. The results of the investigation are as follows. The idea of the identity of the local cultural arts directors was found to be in three directions. First, it is the view that the symbolic role of the artistic supervisory system of the 10 persons guarantees the identity. Second, the identity of local cultural arts directors was recognized as a role to find ways to be localized by developing and debating cultural and artistic discourses in various regions. Third, the participants had a concern and affection for local cultural arts, not one-time but continuous, and recognized it as their identity. The directors who participated in the interviews showed that the discourse of cultural arts in various regions were developed and discussed, and they wanted to find ways to be localized. The roles of local cultural arts directors recognized by research participants in connection with their identity are as follows. First, it should be the subject of systematic and long-term planning that can close the year and connect with the art events of the following year. Second, it should play a role of academic / research that can derive the identity of social and cultural ecological analysis connected with the area. Third, local arts professionals are required to act as cultural brokers, ie local culture professionals, who can create a venue for international cultural exchanges. Research on the form of local government supervision as a mediator of local cultural arts is to find out the origin of the identity of local artists and to establish a methodology for the direction of culture and art as a subject of local people. In addition, there is a need for continued interest and research in providing a reflection on the communication and meaning of the desirable local culture, and suggesting the system for cultivating local cultural arts intermediaries.

COVID-19 Rapid Antigen Test Results in Preschool and School (March 2 to May 1, 2022) (유치원·학교 구성원의 코로나19 신속항원검사 결과(2022년 3월 2일부터 5월 1일까지))

  • Gowoon Yun;Young-Joon Park;Eun Jung Jang;Sangeun Lee;Ryu Kyung Kim;Heegwon Jeong;Jin Gwack
    • Pediatric Infection and Vaccine
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    • v.31 no.1
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    • pp.113-121
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    • 2024
  • Purpose: In response to the surge in coronavirus disease 2019 (COVID-19) omicron variant cases, we have implemented preemptive testing for preschool and school. The purpose is to quickly detect COVID-19 cases using a rapid antigen test (RAT) kit so that normal school activities can continue. Methods: The results entered in The Healthcare Self-Test App were merged with the information on the status of confirmed cases in the COVID-19 Information Management System by Korea Disease Control and Prevention Agency (KDCA) for preschool and school of students and staffs March 2 to May 1, 2022 to analyze the RAT positive rate and positive predictive value of RAT. Results: In preschool and school 19,458,575 people were tested, weekly RAT positive rate ranged from 1.10% to 5.90%, positive predictive value of RAT ranged from 86.42% to 93.18%. By status, RAT positive rate ranged from 1.13% to 6.16% for students, 0.99% to 3.93% for staffs, positive predictive value of RAT ranged from 87.19% to 94.03% for students, 77.55% to 83.10% for staffs. RAT positive rate by symptoms ranged from 76.32% to 88.02% for those with symptoms and 0.34% to 1.11% for those without symptoms. As a result of preschool and school RAT, 943,342 confirmed cases were preemptively detected, before infection spread in preschool and school. Conclusions: RAT was well utilized to detect confirmed cases at an early stage, reducing the risk of transmission to minimize the educational gap in preschool and school. To compensate for the limitations of RAT, further research should continue to reevaluate the performance of RAT as new strains of viruses continue to emerge. We will have to come up with various ways to utilize it, such as performing periodic and repeated RAT and parallel polymerase chain reaction.