Kori Unit 1 nuclear power plant is a pressurized water reactor type with an output of 587 Mwe, which was permanently shut down on June 18, 2017. Currently, the final decommissioning plan (FDP) has been submitted and review is in progress. Once the FDP is approved, it is expected that dismantling will begin with the secondary system, and dismantling work on the primary system of Kori Unit 1 will begin after the spent nuclear fuel is taken out. It is expected that the space where the secondary system has been dismantled can be used as a temporary storage place, and the entire dismantling schedule is expected to proceed without delay. The main equipment of the secondary system is large and heavy. The rotating parts is connected to a single axis with a length of about 40 meters, and is complexly installed over three floors, making accessibility very difficult. A large pipe several kilometers long that supplies various fluids to the secondary system is installed hanging from the ceiling using a hanger between the main devices, and the outer diameter of the pipe is wrapped with insulation material to keep warm. In nuclear secondary system decommissioning, it is very important to check for radiation contamination, establish and implement countermeasures, and predict and manage safety and environmental risks that may occur when cutting and dismantling large heavy objects. So we plan to evaluate the radiation contamination characteristics of the secondary system using ISOCS (In- Situ Object Counting System) to check for possible radioactive contamination. According to the characteristics results, decommissioning plans and methods for safe dismantling by workers were studied. In addition, we conducted research on how to safely dismantle the secondary system in terms of industrial safety, such as asbestos, cutting and handling of heavy materials and so on. This study proposes a safe decommissioning method for various risks that may occur when dismantling the secondary system of Kori Unit 1 nuclear power plant.

PURPOSES : In this study, we aim to broaden the understanding of the factors influencing the accuracy of WIM systems for overload enforcement. Particularly, we explored the proportions and causes of secondary influencing factors (driving path, vehicle class, and acceleration), which have been relatively less studied and reduced the accuracy of the WIM system. METHODS : Overload enforcement data were recorded by the WIM system, and enforcement officers were gathered. The ratios of each data point, which are the relative errors, are used to estimate the accuracy of the WIM system. These relative errors were classified into four driving-path groups, four vehicle-class groups, and three acceleration groups. The change in the accuracy of the WIM system caused by each influencing factor was analyzed by comparing the difference in the average relative error between the classified groups. Analysis of variance (ANOVA) and Welch's ANOVA were used to determine significant differences between groups. RESULTS : Vehicles departing from a normal driving path make it difficult for the GVW compensation algorithm of the WIM system to operate properly. For these abnormal paths, the standard deviation of the average GVW relative error was 22%. There was no specific trend in the difference in accuracy by vehicle class. However, we found that the rear axle and retractable axle were the main causes of the reduced GVW accuracy in each vehicle class. The average GVW relative error remained the same regardless of the acceleration, but the average FAW relative error of the accelerated vehicle was approximately 2.5% lower than that of the unaccelerated vehicle. CONCLUSIONS : An abnormal driving path, lifting of a retractable axle, and rapid acceleration (or deceleration) reduce the accuracy of WIM systems. Intelligent transportation systems, such as traffic signals, telematics devices, and applications that induce desirable driving are required for effective overload enforcement. Additionally, it is necessary to smoothen the road pavement to minimize the dynamic effects on the rear axle.

엘니뇨는 전지구적인 규모로 기후 변화를 유발하는 대표적인 해양-대기 상호작용 현상으로서 지구과학 분야에서 매우 중요한 교수-학습 소재로 사용되고 있다. 본 논고에서는 적도 해류계의 분포 특징 및 발생 역학에 관해 정리하였으며, 엘니뇨 시기의 적도 해류계 변동과 관련 오개념에 관해 조사하였다. 엘니뇨 시기에는 북적도해류, 남적도해류, 적도잠류들이 유의미하게 약화된다. 그러나 북적도반류는 중심축을 중심으로 남쪽 성분은 강화되고 북쪽 성분은 약화되면서 적도 쪽으로 남하하기 때문에 엘니뇨 시기의 북적도반류의 변동에 대해서는 일반화할 수 없다. 또한 서태평양에서는 북적도반류의 남하 폭이 커져 결과적으로 적도 서태평양에서는 동향류가 관측된다. 일부 대중 매체를 통한 과학 기사, 중등학교 평가 문항 뿐만 아니라 현직 교사들을 대상으로 한 설문 조사 결과 분석을 통해 엘니뇨 시기의 적도 해류계의 변동에 관한 개념이 통일되지 않았음을 확인하였다. 이는 기존에 사용되고 있는 엘니뇨 모식도의 부정확한 해석과 적도 해류 및 파동 역학에 관한 이해 부족과 연관된다고 유추할 수 있다.

Seismic qualification of equipment including piping is performed by using floor response spectra (FRS) or in-structure response spectra (ISRS) as the earthquake input at the base of the equipment. The amplitude of the FRS may be noticeably reduced when obtained from coupling analysis because of interaction between the primary structure and the equipment. This paper introduces a method using a modal synthesis approach to generate the FRS in a coupled primary-secondary system that can avoid numerical instabilities or inaccuracies. The FRS were generated by considering the dynamic interaction that can occur at the interface between the supporting structure and the equipment. This study performed a numerical example analysis using a typical nuclear structure to investigate the coupling effect when generating the FRS. The study results show that the coupling analysis dominantly reduces the FRS and yields rational results. The modal synthesis approach is very practical to implement because it requires information on only a small number of dynamic characteristics of the primary and the secondary systems such as frequencies, modal participation factors, and mode shape ordinates at the locations where the FRS needs to be generated.

Seismic responses due to the dynamic coupling between a primary structure and secondary system connected to a structure are analyzed in this study. The seismic responses are compared based on dynamic coupling criteria and according to the error level in the natural frequency, with the recent criteria being reliant on the error level in the spectral displacement response. The acceleration responses and relative displacement responses of a primary structure and a secondary system for a coupled model and two different decoupled models of two degrees-of-freedom system are calculated by means of the time integration method. Errors in seismic responses of the uncoupled models are reduced with the recent criteria. As the natural frequency of the secondary system increases, error in the natural frequency decreases, but seismic responses of uncoupled models can be underestimated compared to that of coupled model. Results in this paper can help determine dynamic coupling and predict uncoupled models’ response conservatism.

디젤엔진에서는 2차 분사 시스템은 다양한 배기 시스템에 적용이 가능하고, 엔진 제어와 관계없이 독립적으로 제어가 가능하기 때문에 환원제 희석 면에서도 후분사 또는 다른 농후한 환원제 분위기 형성 방법 등에 비해 장점이 많다. 2차 분사 시스템에서는 환원제의 공급 방법에 따라서 촉매의 효율은 달라질 수밖에 없다. 환원제는 일정압력 이상으로 유지 및 최적화가 필요하고, 인젝터의 위치 및 각도의 선정은 매우 중요한 인자이다. 본 논문에서는 2차 분사 조건을 변화시켜 환원제의 농도와 양을 변화시켰다. De-NOx 촉매 시스템에서 최대의 NOx 정화 효율에 적합한 환원제 분사 조건들의 선정이 필요하고, 분무 도달거리, 분무 평균 입경, 분무각, 분사량 등의 분무 특성과 환원제의 균일 분포를 잘 파악하여야 한다. 이와 같은 목적을 위하여 2차 분사에서 충돌판 형상에 의한 분무 및 거동 특성은 가시화 방법과 디지털 화상 처리 기법을 사용하여 분석하였으며, 충돌판 형상의 영향성과 각 형상에 대한 최적 각도 범위를 도출하였다.

A new in-service teaching certificate system, the TEE Certificate system, was launched for Korean teachers of English with the aim of encouraging them to use English in their daily teaching practice. This study attempts to investigate key issues regarding the current development of the TEE Certificate system and addresses the implications for a successful TEE policy in Korea. It employs document analysis produced by the Ministry of Education, Science and Teclmology and to key Regional Offices of Education and semi-structured interviews with 15 supervisors, 11 teachers and 2 TEE Certificate examiners. The research findings suggest that there is a gap regarding the aims of the TEE Certificate system among stakeholders, leading to the different attitudes toward it. Those who have positive perceptions of the system see it as a tool for encouraging Korean teachers of English to develop their English language teaching competence. On the other hand, those who have negative attitudes see the negative aspects such as another type of burden on teachers and even the possibility of a form of lay-off. The new strategies of how to use the system are required to make it play a proper role in terms of the provision of an English-fi'iendly learning environment and supporting teachers' professional development.

This paper aims to examine the online learning service called the Cyber Home Learning System (CHLS), which was introduced in 2004 and has been in operation nationwide since 2005. It appears questionable as yet whether the CHLS has obtained a promising outcome. This study, therefore, aims to investigate how many secondary students are currently utilizing the English contents in the CHLS and how they perceive this service. The results of this study indicated that English contents of the CHLS were utilized by only a small number of students, and the contents were rarely perceived as useful. In particular, students perceived that there was little interaction with teachers in cyber space as well as in a classroom setting. Furthermore, five items were identified as the major reasons that hinder students from using the CHLS: lack of promotion; difficulty of self-directed learning; lack of time; low quality; and inconvenience. The results of this study suggest that teachers are influential in affecting students’ perception toward the CHLS, and that it is of paramount importance to renew the CHLS based on the results of a needs analysis.

It recently became evident that the EFL needs of secondary school students could not be met by the then-current complement of teachers. This led to an increase in the number of Conversational English Instructors in the public school system. This growing demand for EFL instructors in our nation‟s public schools requires an obligation to examine the selection criteria and process for incoming EFL instructors. Based on our analysis of a nationwide survey of EFL Instructors, we recommend reforms to the selection process system. A total of 199 EFL instructors in secondary schools including those in Seoul, metropolitan cities, medium-sized cities, and small communities participated in the main survey. The survey considered the entire EFL Instructor selection process including the 1st step of applicant specifications, the 2nd step of teaching-learning performance test and interview test. Our analysis suggests that the selection criteria should include the applicant‟s proficiency test score in spoken and written English, and the teaching-learning performance should be emphasized in a greater extent. This research suggests that the way of testing the applicants‟ teachinglearning performance in the 2nd step selection process should be changed into a more authentic microteaching situation, and that regional needs vary and must be considered in the selection process.

A wastewater treatment plant consists of unit processes designed to achieve specific waste reduction goals. However, offensive odors associated with the treatment processes are a constant source of public complaints. The purpose of this study was to statistically determine the process parameters that influence the formation of volatile sulfur conpounds (VSCs) in the secondary treatment system. A statistical model was developed to relate the process parameters to the formation of VSCs in this system. The model established that F{M ratio, sludge blanket depth and SSV60 were the dominant process parameters that would influence the formation of VSCs in the secondary sedimentation basin. This model provides a useful tool for plant engineers to predict and control the VSCs formation in an secondary activated sludge system.

We propose the development and test result of new optical axis alignment system for the interchangeable F/8 secondary mirror of the BOAO 1.8m telescope system. Since the original system was not equipped with a suitable optical alignment facility, the whole alignment process was performed by hand. It was necessary at least three persons working more than 2 nights and the altitude of the telescope could not exceed 10 degrees, in such altitude the alignment quality was not so good by atmospheric effect. The new system adopts position readable motorized system and remote control operation by the computer installed in observation room, which reduces the number of workers to only one and eliminates the altitude restriction. The defocused CCD image pair obtained at higher altitude makes the aberration estimates more accurately and the number of required alignment loops is reduced from 10 to 4. The system has been installed on September 1, and performed alignment three times. The test results show that the system is stable and accurate, gives better optical performance of the telescope under F/8 focus. We hope to emphasize the fact that the new system will increase observation time of the telescope by about 20 nights per year assuming one alignment in every month.

본 연구는 코로나19(COVID-19) 2년차에 접어든 현재 시점을 기준으로 초‧중등 국악 수업을 담당하고 있는 교사들이 원격교육 체제에서 국악 수업을 운영하고 있는 방식과 이에 대한 인식을 분석함으로써 초‧중등 국악교육의 현안 과제를 논의하는 데 목적을 두었다. 이를 위해 전국의 초‧ 중등 교사 70명을 대상으로 설문조사를 실시하고, 원격 국악 수업을 실행한 경험이 있는 교사를 대상으로 면담을 진행하였다. 설문조사와 면담을 통해 국악 수업에 적용된 원격수업의 유형, 원격 수업 유형에 따른 국악 활동의 적용 실태 및 난점, 원격 국악 수업에 활용한 플랫폼 및 콘텐츠, 원격 국악 수업의 긍정적‧부정적 측면, 교사 역량에 대한 인식, 지원사항에 대한 인식을 분석하였다. 이에 기초하여 국악교육이 당면한 과제를 ‘초‧중등 교육과정 기반의 국악 수업용 콘텐츠 개발 및 제공’, ‘콘텐츠 제작 및 활용을 위한 저작권 해결’, ‘원격수업을 위한 국악교육 연수 제공’, ‘국악 교육을 위한 원스톱 플랫폼 지원’의 네 가지로 제시하고, 이에 대해 논의하였다. 본 연구는 국악교육의 직접적인 실행자인 초‧중등 교사들의 경험과 인식에 기초하여 앞으로의 방향성을 모색한 의의가 있다. 본 연구를 바탕으로 원격 국악 수업에 대한 사회적‧교육적 관심과 인식이 높아지고, 실효성 있는 국악 수업 지원 방안이 활발히 논의되기를 기대한다.

The purpose of this study was to propose a practical way of teacher selection system to recruit a high quality teacher based on the current teacher recruitment system. To achieve the goal of this purpose, the employed method was the related literature review and data analysis. Through this process, the following conclusions were derived as such: To acquire a high quality teacher, the current teacher selection system should be restructured to the direction of enhancing the teacher professionality. In a quite strict sense, the current teacher selection and the recruitment process had nothing to do with the high quality teacher selection and recruitment resulted from a lack of evaluation system with reliability and validity. Even essay test and interview test did not guarantee the objectiveness and reliability because of no feedback from teacher training institutes. Therefore, it is proposed that various evaluation tool must be developed considering the dimension of cognitive, affective, and social characteristics of a teacher, not simple questions and stereotyped interview.

The reaction path of water-gneiss in 200m borehole at the Soorichi site of Yugu Myeon, Chungnam was simulated by the EQ3NR/EQ6 program. Mineral composition of borehole core and fracture-filling minerals, and chemical composition of groundwater was published by authors. In this study, chemical evolution of groundwater and formation of secondary minerals in water-gneiss system was modelled on the basis of published results. The surface water was used as a starting solution for reaction. Input parameters for modelling such as mineral assemblage and their volume percent, chemical composition of mineral phases, water/rock ratio reactive surface area, dissolution rates of mineral phases were determined by experimental measurement and model fit. EQ6 modelling of the reaction path in water-gneiss system has been carried out by a flow-centered flow through open system which can be considered as a suitable option for fracture flow of groundwater. The modelling results show that reaction time of 133 years is required to reach equilibrium state in water-gneiss system, and evolution of present groundwater will continue to pH 9.45 and higher na ion concentration. The secondary minerals formed from equeous phase are kaolinite, smectite, saponite, muscovite, mesolite, celadonite, microcline and calcite with uincreasing time. Modeling results are comparatively well fitted to pH and chemical composition of borehole groudwater, secondary minerals identified and tritium age of groundwater. The EQ6 modelling results are dependent on reliability of input parameters: water-rock ratio, effective reaction surface area and dissolution rates of mineral phases, which are difficult parameters to be measured.