The Gymnocalycium mihanovichii has been an important export item of Korean flower industry for a long time. Although there is a high demand for grafted cactus from overseas, its production for export is limited. In this study, the growth and marketable yield characteristics of Gymnocalycium mihanovichii ‘I-Hong’ were compared between soil culture and ebb-and-flow hydroponic system with single- or double-tier bench. As a result, hydroponic methods with single-tier bench resulted in higher fresh weight and glove diameter compared to other cultivation methods. In the ebb-and-flow hydroponic system, hydroponic system with double-tier bench of grafted cactus traits has a lower growth rate than other cultivations. However, the hydroponic system with double-tier bench of grafted cactus significantly increased the yield. In conclusion, the yield from hydroponic system with double-tier bench was better than soil cultivation method. Although there were some differences in color depending on the cultivation method, it was considered that there was no difference in appearance of Gymnocalycium mihanovichii ‘I-Hong’. Our results suggest the cultivation methods to overcome production constraints, expand their exports, and improve the value-added characteristics of grafted cactus.

본 연구는 노인의 여가 열정이 자기효능감, 여가몰입 및 삶의 질에 미 치는 영향을 규명하고 여가 열정과 삶의 질의 관계에서 자기효능감과 여 가몰입의 매개 효과를 밝히는 데 목적이 있다. 이를 위해 서울·경인 지역 65세 이상 노인을 대상으로 설문조사를 진행, SPSS 24.0 및 AMOS 24.0 프로그램을 활용하여 빈도분석, 기술통계분석, 신뢰도 검증, 탐색적 요인분석, 확인적 요인분석, 상관관계분석, 구조방정식모형분석 및 매개 효과분석을 실시하였다. 분석결과, 노인의 여가 열정은 자기효능감과 여 가몰입에 정의 영향을 미쳤으나 삶의 질에는 유의한 영향을 미치지 않았 다. 반면, 노인의 자기효능감과 여가몰입은 삶의 질에 각각 정의 영향을 미쳤다. 또한, 노인의 여가 열정과 삶의 질의 관계에서 자기효능감과 여 가몰입은 각각 긍정적 매개 효과가 검증되었다. 이로써 노인의 여가 열 정이 높을수록 자기효능감은 높아지고 여가활동에 더 몰입할 수 있게 된 다는 점, 노인의 여가 열정이 삶의 질에 직접 긍정적인 영향을 미친다고 단언할 수는 없지만, 여가 열정이 높은 자기효능감과 여가몰입을 통해서 노 인의 삶의 질을 높인다는 측면에서 중요한 동기 및 영향요인이 될 수 있다 는 점을 확인하였다. 이에 따라서 본 연구는 주요 함의와 논의점을 제시하면 서 노인의 삶의 질 향상에 기여하는 노인 여가 차원의 방안들을 제언하였다.

본 연구는 미용 전공 대학생의 비대면 수업 경험이 학습몰입에 미치는 영향에 대해 알아보고 With Corona 시대에 맞는 미용 교육산업에 기초자료를 제공하기 위함에 목적이 있다. 미용 전공 대학생 300명을 대상으로 2022년 06월 07일부터 06월 21일까지 자가기입식 설문법을 실시하였으며 총 286부를 표본으로 실증 분석하였다. SPSS ver. 21.0 프로그램을 활용하여 빈도분석, 요인분석, 탐색적 요인분석, 기 술통계분석, 상관관계분석, 다중회귀분석법을 사용하여 연구하였다. 그 결과, 비대면 학습경험을 요인 분석 한 결과 수업만족 2개의 하위요인으로 분석되었으며 학습몰입을 요인 분석한 결과 학습 즐거움과 학습몰입 의 2개의 하위요인으로 분석되었다. 수업 활동이 학습몰입의 하위요인인 학습 즐거움(β=.279, p<.007)과 학습몰입(β=.221, p<.031)에 통계적으로 유의미한 정(+)의 영향을 미치는 것으로 나타났다(p<.05). 수업 만족이 학습몰입의 하위요인인 학습몰입(β=.223, p<.041)에 통계적으로 유의미한 정(+)의 영향을 미치는 것으로 나타났다(p<.05). 본 연구결과를 토대로 비대면 수업 경험이 학습몰입에 영향을 미친다는 사실을 알 수 있었으며 이를 통해 시대에 맞는 효율적 비대면 교육 방안이 활발히 모색되기를 기대하는 바이다.

The shell & tube-type heat exchanger has been frequently used because it shows simple structure, easy manufacturing and wide operation conditions among many heat exchangers. This study aims to investigate the characteristics for thermal flow of coolant and the possibility of damage for tube equipped with shell due to thermal stress. For these purposes, The thermal flow of coolant in tube was simulated using ANSYS-CFX program and thus the behaviors of coolant were evaluated with standard k-ε turbulence model. As the results, as the flow rate of coolant in tube was increased, the mean relative pressure was also increased with quadratic curve, however, as the surface temperature of tube was increased, mean temperature difference was linearly increased. Finally it showed that the damage of tube could be predicted, that is, which tube was the most weak due to thermal stress.

Given the domestic situation, all nuclear power plants are located at the seaside, where interim storage sites are also likely to be located and maritime transportation is considered inevitable. Currently, Korea does not have an independently developed maritime transportation risk assessment code, and no research has been conducted to evaluate the release rate of radioactive waste from a submerged transportation cask in the sea. Therefore, secure technology is necessary to assess the impact of immersion accidents and establish a regulatory framework to assess, mitigate, and prevent maritime transportation accidents causing serious radiological consequences. The flow rate through a gap in a containment boundary should be calculated to determine the accurate release rate of radionuclides. The fluid flow through the micro-scale gap can be evaluated by combining the flow inside and outside the transportation cask. In this study, detailed computational fluid dynamic and simplified models are constructed to evaluate the internal flow in a transportation cask and to capture the flow and heat transfer around the transportation cask in the sea, respectively. In the future, fluid flow through the gap will be evaluated by coupling the models developed in this study.

In this paper, numerical simulations were conducted to secure both flow distribution and uniform flow discharge through a wall mount type air sterilizer. In order to increase the reliability of the simulation results where there is no well-known validation case for air sterilizer, mesh sensitivity study was performed under the constraint that y+ set to one for k-w SST turbulent modeling for both the air sterilizer and the fan. The installation of various guides and structures was reviewed in the point of flow distribution and pressure drop inside the sterilizer, and the exhaust pressure conditions were predicted to secure uniform flow discharge at outlets. This study has been done based on the computational analysis during the development stage of the air sterilizer, and the results will be verified through physical testing after production of prototype.

본 연구에서는 대마난류(Tsushima Warm Current, TWC)의 유동 변화에 영향을 주는 요소를 파악하기 위하여 TWC의 수송량과 태 평양 순년진동(Pacific Decadal Oscillation, PDO) 및 엘니뇨 남방진동(El Niño - Southern Oscillation, ENSO)의 상호 관계 분석을 실시하였다. 25 년(1993~2018년) 동안의 TWC의 월별 수송량을 계산해보면 하계에 가장 크고 동계에 가장 작게 나타나는 계절변동 주기가 뚜렷하다. TWC 수송량과 PDO 및 ENSO의 한 척도인 Oceanic Niño Index(ONI) 각각의 주기성 파악을 위한 power spectrum 분석결과, TWC 수송량은 1년 주기 에서 peak를 보이지만 PDO 및 ONI는 뚜렷한 주기가 나타나지 않았다. 또한, TWC 수송량과 PDO 및 ONI의 상호 관계 파악을 위해 coherence 추정 방법을 이용하여 분석하였다. PDO 및 ONI의 coherence는 3년 이상의 장주기 변동에서 상호 기여도가 높으나 1년 이내의 단주기 변동 에서는 상호 기여도가 낮다. 그러나 TWC 수송량과 PDO 두 요소 간 0.8~1.2년 주기에서 coherence 값은 0.7로 상호 기여도가 높다. 한편 서수 도를 통과하는 TWC 수송량과 PDO는 Ⅰ기간(1993~2002년)과 Ⅲ기간(2010~2018년)에 역상관 관계성을 가진다. TWC 최대 수송량 (2.2 Sv 이 상)이 높게 나타나는 시기에 PDO 지수가 –1.0 이하의 음의 값, 2.2 Sv 이하로 작은 시기에 PDO 지수가 양의 값을 나타낸다. 따라서 장기적 인 PDO 지수 자료를 이용하면 TWC 수송량 변동 및 동해 연안역의 수온변화를 예측 또한 가능할 것으로 판단된다.

In this study, two ventilation holes were considered to prevent condensation in the circular column supporting the provision crane on a training ship(Saenuri) for Mokpo National Maritime University. The ventilation holes could be understood as the most simple and inexpensive way to prevent condensation because it was formed only by drilling. If sufficient ventilation is provided, the insulation and corrosion of an electric motor can be improved, and a comfortable state can be ensured in the circular column. The circular column had an electric motor for driving the provision crane so that the basic principle was to utilize the kinetic energy for the flow field from a cooling fan in the circular column. The ventilation holes attenuated the low-velocity area in the circular column and contributed to internal flow circulation with updrafts. The results were discussed through numerical analysis based on computational fluid dynamics.

AlSi10Mg alloys are being actively studied through additive manufacturing for application in the automobile and aerospace industries because of their excellent mechanical properties. To obtain a consistently high quality product through additive manufacturing, studying the flowability and spreadability of the metal powder is necessary. AlSi10Mg powder easily forms an oxide film on the powder surface and has hydrophilic properties, making it vulnerable to moisture. Therefore, in this study, AlSi10Mg powder was hydrophobically modified through silane surface treatment to improve the flowability and spreadability by reducing the effects of moisture. The improved flowability according to the number of silane surface treatments was confirmed using a Carney flowmeter. In addition, to confirm the effects of improved spreadability, the powder prior to surface treatment and that subjected to surface treatment four times were measured and compared using s self-designed recoating tester. The results of this study confirmed the improved flowability and spreadability based on the modified metal powder from hydrophilic to hydrophobic for obtaining a highquality additive manufacturing product.

The Korea government decided to shut down Kori-1 and Wolsung-1 nuclear power plants (NPPs) in 2017 and 2019, respectively, and their decommissioning plans are underway. Decommissioning of a NPP generates various types of radioactive wastes such as concrete, metal, liquid, plastic, paper, and clothe. Among the various radioactive wastes, we focused on radioactive-combustible waste due to its large amount (10,000–40,000 drums/NPP) and environmental issues. Incineration has been the traditional way to minimize volume of combustible waste, however, it is no longer available for this amount of waste. Accordingly, an alternative technique is required which can accomplish both high volume reduction and low emission of carbon dioxide. Recently, KAERI proposed a new decontamination process for volume reduction of radioactivecombustible waste generated during operation and decommissioning of NPPs. This thermochemical process operates via serial steps of carbonization-chlorination-solidification. The key function of the thermochemical decontamination process is to selectively recover and solidify radioactive metals so that radioactivity of the decontaminated carbon meets the release criteria. In this work, a preliminary version of mass flow diagram of the thermochemical decontamination process was established for representative wastes. Mass balance of each step was calculated based on physical and chemical properties of each constituent atoms. The mass flow diagram provides a platform to organize experimental results leading to key information of the process such as the final decontamination factor and radioactivity of each product.

In high-level radioactive waste disposal, a high temperature is generated from the canister containing the waste in the engineered barrier, while groundwater flows into the buffer system from the host rock. The temperature increase and groundwater inflow result in the water phase change and saturation variation. Saturation change is related to the thermal conductivity of buffer material; hence the phase change and saturation strongly interact with the temperature evolution. The complex coupled behavior affects the stability of the whole disposal system, and the security of the repository is critical to human-being life. However, it is difficult to predict the long-term coupled behavior in the disposal system due to the considerable field-test scale, and therefore a numerical simulation is a suitable method having repeatability and cost-effectiveness. DECOVALEX is an international cooperating project for developing numerical methods and models for thermo-hydro-mechanical-chemical (THMC) interaction. DECOVALEX has a four-year cycle with various topics. At the current phase, Task C aims to simulate the full-scale emplacement (FE) experiment performed at Mont Terri underground rock laboratory. Nine research groups are participating in the task, and among them, KAERI simulates the experiment using OGS-FLAC. The simulator combines OpenGeoSys for TH simulation and FLAC3D for M simulation. Through the benchmark simulation, we verified OGS-FLAC for the two-phase flow analysis in the disposal system and finally modeled the FE experiment with a three-dimensional grid. We performed a simple sensitivity analysis to investigate the effect of input parameters on the two-phase flow system and confirmed that the compressibility and permeability affected the flow behavior. We also compared the simulation results to the field data and obtained well-matched results from a series of simulation.

As the saturation rate of temporary storage facilities for spent nuclear fuel increases, regulatory demands such as interim storage and permanent disposal of spent nuclear fuel are expected to begin in earnest. Considering the domestic situation where all nuclear power plants are located on the waterfront site, the interim storage site is also likely to be located on the waterfront site, and maritime transportation is one of the essential management stages. Currently, there are no independently developed maritime transportation risk assessment code in Korea, and no research has been conducted to evaluate the release of radioactive waste due to the sinking of transport container. Therefore, it is necessary to secure technology to properly reflect the domestic maritime transportation environment and to assess the impact of the sinking accident and to carry out safety regulations. To accurately calculate the releaser rate of radionuclides contained in a cask with breached containment boundary, the flow rate through the gap generated in the containment boundary should be calculated. The fluid flow through this gap which is probably in micro scale in most situations should be evaluated combining the fluid flow inside and outside the cask. In this study, a detailed computational fluid dynamics model to evaluate the internal fluid flow in the cask and a simplified model to capture the fluid flow and the heat transfer around the cask in the sea are constructed. The results for the large scale model are compared with the analytic formula for verification of heat transfer coefficient and they showed good agreements. The heat transfer coefficient thus found can be used in the detailed model to provide more realistic data than those obtained from assumed heat transfer coefficient around the surface of the cask. In the future, fluid flow through the gap between the lid and the body of the cask will be evaluated coupling the models developed in this work.

Material balance evaluation is an important measure to determine whether or not nuclear material is diverted. A prototype code to evaluate material balance has been developed for uranium fuel fabrication facility. However, it is difficult to analyze the code’s functionality and performance because the utilization of real facility data related to material balance evaluation is very limited. It is also restricted to deliberately implement various abnormal situations based on real facility data, such as nuclear diversion condition. In this study, process flow simulator of uranium fuel fabrication facility has been developed to produce various process data required for material balance evaluation. The process flow simulator was developed on the basis of the Simulink-SimEvents framework of the MathWorks. This framework is suitable for batch-based process modeling like uranium fuel fabrication facility. It dynamically simulates the movement of nuclear material according to the time function and provides process data such as nuclear material amount at inputs, outputs, and inventories required for Material Unaccounted For (MUF) and MUF uncertainty calculation. The process flow simulator code provides these data to the material balance evaluation code. And then the material balance evaluation code calculates MUF and MUF uncertainty to evaluate whether or not nuclear material is diverted. The process flow simulator code can simulate the movement of nuclear material for any abnormal situation which is difficult to implement with real process data. This code is expected to contribute to checking and improving the functionality and performance of the prototype code of material balance evaluation by simulating process data for various operation scenarios.