It is difficult to optimize the process parameters of directly preparing carbonaceous mesophase (CMs) by solvothermal method using coal tar as raw material. To solve this problem, a Decision Tree model for CMs preparation (DTC) was established based on the relationship between the process parameters and the yields of CMs. Then, the importance of variables in the preparation process for CMs was predicted, the relationship between experimental conditions and yields was revealed, and the preparation process conditions were also optimized by the DTC. The prediction results showed that the importance of the variables was raw material type, solvothermal temperature, solvothermal time, solvent amount, and additive type in order. And the optimized reaction conditions were as follows: coal tar was pretreated by decompress distillation and centrifugation, the solvent amount was 50.0 ml, the solvothermal temperature was 230 °C, and the reaction time was 5 h. These prediction results were consistent with the actual experimental results, and the error between the predicted yields and the actual yields was about − 1.1%. Furthermore, the prediction error of DTC method was within the acceptable range when the data sample sets were reduced to 100 sets. These results proved that the established DTC for chemical process optimization can effectively lessen the experimental workload and has high application value.

본 연구의 목적은 대학생의 진로 스트레스, 마음 챙김이 진 로 탐색행동에 미치는 영향 및 진로 스트레스가 마음 챙김에 미치는 영향을 분석하는 데 있었다. 이를 위해 설정한 연구가 설은 다음과 같다. 첫째, 진로 스트레스가 진로 탐색행동에 영 향을 미칠 것이다. 둘째, 진로 스트레스가 마음 챙김에 영향을 미칠 것이다. 셋째, 마음 챙김이 진로 탐색행동에 영향을 미칠 것이다. 본 연구를 위해 랴오닝성 심양시(遼寧省瀋陽市)에 위치한 대 학의 남녀 학생 270명을 대상으로 설문조사를 실시하였다. 이 연구를 진행하기 위하여 2022년 7월부터 2022년 8월까지 1개월 동안 설문조사를 실시하였다. 연구 도구는 진로 스트레스 척도, 마음 챙김 척도, 진로 탐색행동 척도를 사용하였다. 본 연구에서 통계프로그램인 SPSS 21.0을 사용하여 빈도분 석, 신뢰도 분석, 요인분석, 상관 분석 및 단순 회귀분석, 다중 회귀분석 등을 실시하였다. 본 연구의 결과는 다음과 같다. 첫째, 진로 스트레스가 진로 탐색행동에 부(-)적인 영향을 미치는 것으로 나타났다. 둘째, 진로 스트레스가 마음 챙김에 부(-)적인 영향을 미치는 것으로 확인되었다. 셋째, 마음 챙김이 진로 탐색행동에 정(+)적인 영 향을 미치는 것으로 확인되었다. 이와 같은 연구 결과는 대학생의 진로 탐색행동에 중요하며, 진로 스트레스와 마음 챙김 및 진로 탐색행동을 증진하는 것이 필요함을 시사한다. 끝으로 본 연구 결과에 대하여 논의하였다.

n Korea, the decommissioning of nuclear power plants is being prepared, and a large amount of radioactive waste is expected to be generated. In particular, clearance level waste, which accounts for more than 90%, requires prevention of cross-contamination and prompt classification. In this study, the possible exposure route and the derivation of exposure dose for worker exposure management in a movable analysis system that can be analyzed onsite were studied. The movable radionuclide analysis system is divided into a preparatory room, a sample storage room, a radioanalysis room, a laboratory, and a waste storage room. It consists of one radioanalysis worker and one pre-treatment worker, and the main radiation exposure is expected to occur in the movement path in the sample storage room, radioanalysis room, and laboratory. The source term for the exposure evaluation, the annual usage dose presented in the radiation safety report in the movable radionuclide analysis system was used. The input data for the evaluation of the external exposure dose under normal circumstances (exposure situation, working hours, distance, etc.) is referenced at facility specifications. The internal exposure dose evaluation was assumed to be acute exposure (1 hour) assumed as internal pollution due to the drop in liquid sample during the pretreatment work. As an evaluation method, a method using a calculation formula and a method using an evaluation code was performed. For the evaluation of exposure dose using the calculation formula, a preliminary evaluation was performed using the point source method, the point kernel method, and intake and dose conversion factors. In addition, VISIPLAN and IMBA codes were used to evaluate exposure dose using the evaluation code, and the input data were supplemented for evaluation. As a result of the evaluation, the annual exposure dose limit of 20 mSv was satisfied for both normal and non-normal situations. In future research, it is planned to derive the evaluation results by particular scenarios for the detailed movement route and evaluation time according to the work process in the mobile radionuclide analysis.

Under Article 17 of the Radioactive Waste Management Act and Article 12 of the Enforcement Decree of the Radioactive Waste Management Act, KHNP shall reserve the cost for the decommissioning of NPPs as provisions. To preserve the value, an additional amount considering the discount rate is to be added annually. The initial provision is decided by estimating the decommissioning cost of NPP at the time of commercial operation, calculating the future cost by applying the inflation rate to the expected start date of decommissioning, and then discounting it at a discount rate to the present value. According to the current notice, the period for applying inflation and discount rate is defined as the period of 5 years added to the design life of NPP, which is presumed to be due to the assumption that all decommissioning costs are incurred at once 5 years after the permanent shutdown of the power plant. However, assuming that the actual decommissioning period of a domestic nuclear power plant is generally planned for 15 years, it can be expected that most of the decommissioning activities will begin after the decommissioning preparation and transition period, or 5 years after permanent shutdown of the plant. Considering this, it can be said that the current period (5 years + design life) for applying inflation and discount rate is set a little conservatively. In this paper, the initial provision is calculated by appropriately distributing the decommissioning costs of overseas NPPs categorized by International Structure for Decommissioning Costing (ISDC) during the planned decommissioning period of domestic NPPs, and then adding up the decommissioning cost each year by separately applying the inflation and discount period, which was compared with the results calculated using the current method. Through this, it was confirmed that the revised method had the effect of reducing the initial provision by 2.2% to 5.7% compared to the current method depending on the gap between inflation rate and discount rate, which can be converted to about 8 years of inflation and discount period used in the current method. It is expected that this paper will be used in the future as a basic reference for developing a more accurate method for calculating the initial provision of decommissioning cost.