The demand for chiller equipment that keeps each machine at a constant temperature to maintain the best possible condition is growing rapidly. PID (Proportional Integral Derivation) control is a popular temperature control method. The error, which is the difference between the desired target value and the current system output value, is calculated and used as an input to the system using a proportional, integrator, and differentiator. Through such a closed-loop configuration, a desired final output value of the system can be reached using only the target value and the feedback signal. Furthermore, various temperature control methods have been devised as the control performance of various high-performance equipment becomes important. Therefore, it is necessary to design for accurate data-driven temperature control for chiller equipment. In this research, support vector regression is applied to the classic PID control for accurate temperature control. Simulated annealing is applied to find optimal PID parameters. The results of the proposed control method show fast and effective control performance for chiller equipment.

As cable TV, which has been leading the paid broadcasting market, has given the lead to IPTV, which has huge communication capital, its competitiveness is gradually weakening. This study examines the operation status of local cable TV and seeks ways to strengthen competitiveness for survival. To this end, we conducted data analysis such as related statistics, broadcasting industry survey reports, IPTV growth reports, CMB management indicators, paid broadcasting literature data, marketing reports, industry success stories, and marketing mix and SWOT analysis. As a result, four strategies for strengthening the survival competitiveness of local cable TV, namely joint purchase apartment marketing strategy, influencer marketing strategy, relationship marketing strategy, and digital marketing strategy were derived. Therefore, the results of this study can contribute to the improvement of the competitiveness of local cable TV, which has been with local residents through close content, and can be used as basic data for establishing marketing strategies for local cable TV in the future.

The purpose of this action study was to identify problems of pre-service English teachers within the context of the COVID-19 pandemic, initiate appropriate actions, and measure impacts. As the lack of teacher training and practice was noted as a problem, actions of providing long-term training and online teaching practice were initiated. Eighteen pre-service English teachers took an ICT course to receive training and taught students online. Their responses in regular group conferences, a final conference, and a survey questionnaire were analyzed through observing and reflecting. They perceived all topics and contents covered for the training as very useful. They also reported online teaching practice enabled them to improve various abilities such as managing Zoom classes, creating video content, managing an app, etc. Finally, they experienced difficulty, particularly in keeping students motivated, and holding online mentoring. However, working collaboratively enabled them to become more responsible. Actions initiated in this study were confirmed to be successful. Implications for the future are presented.

The purpose of this study was to propose useful suggestion by analyzing preventive replacement policy under which there are minor and major failure. Here, major failure is defined as the failure of system which causes the system to stop working, however, the minor failure is defined as the situation in which the system is working but there exists inconvenience for the user to experience the degradation of performance. For this purpose, we formulated an expected cost rate as a function of periodic replacement time and the number of system update cycles. Then, using the probability and differentiation theory, we analyzed the cost rate function to find the optimal points for periodic replacement time and the number of system update cycles. Also, we present a numerical example to show how to apply our model to the real and practical situation in which even under the minor failure, the user of system is not willing to replace or repair the system immediately, instead he/she is willing to defer the repair or replacement until the periodic or preventive replacement time. Optimal preventive replacement timing using two variables, which are periodic replacement time and the number of system update cycles, is provided and the effects of those variables on the cost are analyzed.

DEA(data envelopment analysis) is a technique for evaluation of relative efficiency of decision making units (DMUs) that have multiple input and output. A DEA model measures the efficiency of a DMU by the relative position of the DMU’s input and output in the production possibility set defined by the input and output of the DMUs being compared. In this paper, we proposed several DEA models measuring the multi-period efficiency of a DMU. First, we defined the input and output data that make a production possibility set as the spanning set. We proposed several spanning sets containing input and output of entire periods for measuring the multi-period efficiency of a DMU. We defined the production possibility sets with the proposed spanning sets and gave DEA models under the production possibility sets. Some models measure the efficiency score of each period of a DMU and others measure the integrated efficiency score of the DMU over the entire period. For the test, we applied the models to the sample data set from a long term university student training project. The results show that the suggested models may have the better discrimination power than CCR based results while the ranking of DMUs is not different.

The purpose of this study is to suggest a plan to improve the level of acceptance of related technologies and the transition to smart factories of small and medium-sized manufacturing enterprises by using ‘technology readiness’ and ‘integrated technology acceptance model’. To this end, the research hypothesis was verified by collecting questionnaire data from 130 small and medium- sized manufacturing companies in Korea and conducting path analysis. First, optimism affects performance expectations, social influence, and facilitation conditions, innovation affects performance expectations, effort expectations, and social influence, discomfort affects performance expectations, social influence, and facilitation conditions, and anxiety affects effort expectations, social influence and facilitation conditions. has been proven to affect Finally, performance expectations, effort expectations, social influence, and facilitation conditions were verified to have a significant positive effect on the intention to accept technology.

현대의 기술은 비약적으로 발전하고 있으나 그러한 기술적 진보가 안전수준 의 향상도에 직접적으로 비례하지는 않는다. 새로운 기술과 그것의 운용은 또 다른 위험요소를 낳기 때문이다. 본 논문은 현대 해사에서 최신기술의 집약체 인 자율운항선박의 안전관리를 현행 ISM Code상 규정에 근거하여 검토한다. 먼저 ISM Code상 핵심주체들의 역할과 책임을 자율운항선박에 적용 가능한지 분석해 보고, 특히 ISM Code에서 정의하는 선장의 책임과 권한이 자율운항선 박에서 어떻게 적용되어야 할 것인지를 집중적으로 살펴본다. 또한 현행 ISM Code상 핵심주체의 역할에 더하여 원격운항센터, 원격운항자, 사이버보안 등 추가적으로 ISM Code에 규정되어야 하는 부분에 대해서도 접근 방향을 제시한 다. 특히 원격운항의 도입에 따른 공백을 채우기 위해 자율운항 단계별로 새로 운 역할의 도입을 제안한다. 이로써 이 논문은 자율운항선박에 대한 효과적인 안전관리를 위한 안전관리체제의 틀을 제시한다.

The present study analyzed small group interaction in the videoconferencing-mediated English class at a university in South Korea. Adopting the ‘affordance’ construct (van Lier, 2004) as a conceptual framework for interpreting small group work, the goals of the research are to 1) identify the types of linguistic affordances emerging in videoconferencing-mediated small group work and 2) examine learners’ perceptions and responses to the linguistic affordances. Data were collected from two major sources: 40 video recording files of small group observation and post-class interviews with four students. The paper analyzed 13 extracts selected from the transcription of the video recordings. The overall results of the research suggest that a range of linguistic affordances emerged through interaction and participants responded to the affordances they perceived in various ways. Three types of linguistic affordances were observed in the data: technology-generated affordances, learner-generated affordances, and learner-to-learner-generated affordances. The study findings have important implications for providing new insights into the operationalization of the affordance construct as well as advancing the understanding of the affordance perspective of L2 learning.

This study examines the concept of Korean ethnicity by looking into how the Choseonjok, ethnic return migrants from China, are perceived in online news comments. Data were collected from 3,109 comments, which were written in response to 28 news articles regarding the Choseonjok, and analyzed using a Python-based text-mining technique and critical discourse analysis. The findings show that the commenters perceived the Choseonjok negatively, including as potential criminals or social vice. They not only placed the Choseonjok in an inferior position to pure Koreans but also excluded them from the category of compatriots, arguing that speaking the same language and sharing a similar appearance were not enough to make the ethnic return migrants Korean compatriots. This study critically demonstrates how a group of ethnic return migrants is depicted in online public discourses and how this portrayal can shed light on the conceptualization of Korean ethnicity in this era of multiculturalism.