Reducing underwater radiated noise from a ship is a critical issue for ensuring the survivability of the vessel. As high-speed signal processing and interlocking algorithms become more sophisticated, the heat intensity of shipboard equipment is increasing per unit volume. When designing shipboard equipment, it is necessary to consider the trade-off between heat dissipation and noise reduction. Following an analysis of the trade-offs, it was determined that the arrangement of Fan Ass'y A and B exhibited excellent noise and heat dissipation characteristics. Based on this, PWM control operating zones were derived. It was determined that the placement of Fan Ass'y A and B in the operating zone would increase the PWM duty cycle from 33% to 58% using a signal frequency of 25kHz band with guaranteed reliability. This would increase the noise by approximately 9dB(A) but reduce the internal board reference temperature by up to 15℃.

This study focuses on analyzing the energy-saving effects of the recirculation aquaculture system using seawater source heat pumps and solar power generation. Based on the thermal load analysis conducted using the transient system simulation tool, the annual energy consumption of the recirculation aquaculture system was analyzed and the energy-saving effects of utilizing the photovoltaic system was evaluated. When analyzing the heat load, the sea areas where the fish farms are located, the type of breeding tank, and the circulation rate of breeding water were taken into consideration. In addition, a method for determining the appropriate capacity for each operation time was examined when applying the energy storage system instead of the existing diesel generator as an emergency power, which is required to maintain the water temperature of breeding water during power outage. The results suggest that, among the four seas considered, Jeju should be estimated to achieve the highest energy-saving performance using the solar power generation, with approximately 45% energy savings.

A computational analysis was performed to study the thermal characteristics within the injection molding process of polygon mirrors in LiDAR systems. Such polygon mirrors are significantly influenced by the geometric shape of the injection mold as well as temperature and operating conditions. The analysis included the temperature distribution, heat flux, and variations in heat transfer rate of the polygon mirror from initial conditions. From the beginning of the injection process, temperature of the polygon mirror changes rapidly, leading to conductive heat transfer to the mold. There are large variations in the mirror temperature change depending on local position, and surface heat flux are affected by internal cooling path. These results are expected to be used as thermal design data for various polygon mirror processes.

The PCHE(Printed Circuit Heat Exchanger)-type heat exchanger, which was fabricated by etching and diffusion bonding, was used to hydrogen station, VHTR(Very High Temperature Reactor), SMR and so on. The hydrogen station equipped with PCHE-type heat exchanger is necessary to inject the hydrogen gas into facilities, for instance, such as HFCV(Hydrogen Fuel Cell Vehicle) and power systems. The purpose of this study is to investigate the thermal characteristics of thin plate of PCHE depending on constraint conditions through numerical analysis. As the results, it showed that thermal stress of thin plate, which was not performed diffusion bonding at all, was larger than that, which was performed perfect diffusion bonding, and its maximum difference was about 3 times. Further it was confirmed that the thermal characteristics of thin plate could be obtained by investigating the heat flux.

In this research, a detailed analysis of the decay heat contributions of both actinides and non-actinides (fission fragments) from spent nuclear fuel (SNF) was made after 50 GWd·tHM−1 burnup of fresh uranium fuel with 4.5% enrichment lasted for 1,350 days. The calculations were made for a long storage period of 300 years divided into four sections 1, 10, 100, and 300 years so that we could study the decay heat and physical disposal ratios of radioactive waste in medium- and long-term storage periods. Fresh fuel burnup calculations were made using the code MCNP, while isotopic content and then decay heat were calculated using the built-in stiff equation solver in the MATLAB code. It is noted that only around 12 isotopes contribute more than 90% of the decay heat at all times. It is also noted that the contribution of actinides persists and is the dominant ether despite decreasing decay heat, while the effect of fission products decreases at a very rapid rate after about 40 years of storage.

The research aimed to develop a high-efficiency plate-type heat exchanger for exhaust gas using computational fluid dynamics (CFD) thermal analysis based on the plate shape, and to identify the optimal shape. Following this, a water/air plate heat exchanger was manufactured, and its characteristics were studied experimentally. As the Re number increases on the gas (or air) side, the heat transfer rate increases significantly, whereas an increase in the Re number on the water side leads to a smaller increase in heat transfer. This is attributed to the larger convective heat resistance on the gas side, causing a substantial reduction in gas-side heat resistance as gas velocity increases, resulting in a considerable overall reduction in heat resistance. The fluid flow pressure drop showed similar results between the CFD calculations and experimental outcomes.

Dry active wastes (DAWs) are combustible waste generated during the operation and decommissioning of nuclear facilities, and are known to be generated in the amount of approximately 10,000 to 40,000 drums (based on 200 L) per unit. It consists of various types of protective clothing, paper, and plastic bags, and is stored in radioactive waste storage facilities. Therefore, reducing the volume of DAWs is an important issue in order to reduce storage costs and utilize the limited space of waste storage facilities. Heat treatment such as incineration can dramatically reduce the volume of waste, but as the waste is thermally decomposed, CO2, a global warming gas, is generated and there is a risk of emissions of harmful gases including radionuclides. Therefore, a heat treatment process that minimizes the generation of CO2 and harmful gases is necessary. One of the alternatives to incineration is to carbonize DAWs, dispose of carbonized materials below the release standard as non-radioactive waste, and selectively separate and stabilize inorganic components, including radionuclides, from carbonized DAWs. In this study, 13 types of DAWs generated from nuclear power plants were selected and their thermal decomposition characteristics were investigated to design a heat treatment process that replaces incineration. As a result of TGA analysis, the temperature at which thermal decomposition of each waste begins is 260-300°C for cotton, 320-330°C for paper, 315-420°C for synthetic fiber, 350°C for latex gloves. The mass of most samples decreased to less than 1 % of the initial weight after heat treatment, and dust suit and latex gloves had residues of 13.83% and 13.71% of the initial mass, respectively. The metal components of the residue produced after heat treatment of the sample were analyzed by EDS. According to the EDS results, cotton contains Ca and Al, paper contains Ca, Al and Si, synthetic fiber contains Ca, Cu and Ti, latex gloves contain Ca and Mg. Additionally, ICP analysis was performed to quantify the inorganic components. These results are expected to be applicable to the processing of DAW generated at nuclear facilities in the future.

The design and fabrication of suitable waste forms with high thermal and structural stability are essential for the safe management and disposal of radioactive wastes. In particular, the thermal properties and temperature distribution of waste form containing high heat-generating nuclides such as Cs and Sr can be used to evaluate its thermal stability, but also provide useful information for the design of canisters, storage systems, and repositories. In this study, a new program code-based thermal analysis framework has been developed to facilitate the characterization, design, and optimization of the waste form. Matlab was used as a software development platform because it provides powerful mathematical computation and visualization components such as the partial differential equation (PDE) toolbox for solving heat transfer problems using finite element method, the App Designer for graphical user interface (GUI), and the MATLAB Compiler for sharing MATLAB programs as standalone applications and web applications. The thermal analysis results such as temperature distribution, heat flux, maximum/ minimum temperature, and centerline/surface temperature profile are visualized with graphs and tables. To evaluate the effectiveness of the developed program, several design and optimization studies were carried out for the SrTiO3 waste form, selected as a stable form of strontium nuclide.

In general, systems are developed by repeatedly performing the processes of design, analysis, manufacturing, and performance testing. In particular, systems with temperature, pressure, and flow rate often utilize computational fluid dynamics tools at the design stage. In this paper, we aim to verify the reliability of the analysis results of Solidworks Flow Simulation, which is widely used in heat flow analysis at the design stage. A tube furnace was manufactured, various experiments were performed, and a study was conducted to compare the analysis results. The details of the experiment are as follows. First, an experiment was conducted in which the heater was heated to 900°C without insulating the exposed part of the tube. The detailed contents of the experiment are as follows; - Heating heater and measuring temperature without supplying flow inside the tube, - Tube flow supply (25°C, 15 lpm air) and heater heating/temperature measurement. Second, an experiment was performed in which the exposed part of the tube was insulated (thickness 50 mm) and the heater was heated to 900°C. The detailed contents of the experiment are as follows; - Insulate the outside of the tube except for the flanges at both ends of the tube, and heat the heater and measure the temperature without supplying flow inside the tube. - Insulate the outside of the tube except for the flanges at both ends of the tube, supply flow rate inside the tube (25°C, 15 lpm air) and measure heater heating/temperature. - Insulate the flange of the flow supply section, heat the heater and measure temperature without supplying flow inside the tube. - Insulate the flange of the flow supply section, heat the supply air (277°C, 15 lpm) and measure the temperature using a heating gun without heating the heater. - Insulate the flange of the flow supply section, supply heated air (277°C, 15 lpm) and measure heater heating/temperature. - Insulate the flange of the flow supply section and measure temperature according to heater heating (900°C) and supply temperature (25°C, 277°C 15 lpm). The following results were derived from the experimental and analysis results. - When the exposed part of the tube is insulated, the temperature inside the tube increases and the steady-state power decreases compared to non-insulated. - In areas with insulation, the temperature error between experiment and analysis results is not large. - When flow rate is supplied, there is a large temperature error in experiment and analysis results. - The temperature change after the center of the heater is not large for a temperature change of 15 lpm flow rate. From these results, it can be seen that Solidworks Flow Simulation has a significant difference from the experimental results when there is a flow rate in the tube. This was thought to be because the flow rate acts as a disturbance, and this cannot be sufficiently accounted for in the analysis. In the future, we plan to check whether there is a way to solve this problem.

The solid-state chemistry of uranium is essential to the nuclear fuel cycle. Uranyl nitrate is a key compound that is produced at various stages of the nuclear fuel cycle, both in front-end and backend cycles. It is typically formed by dissolving spent nuclear fuel in nitric acid or through a wet conversion process for the preparation of UF6. Additionally, uranium oxides are a primary consideration in the nuclear fuel cycle because they are the most commonly used nuclear fuel in commercial nuclear reactors. Therefore, it is crucial to understand the oxidation and thermal behavior of uranium oxides and uranyl nitrates. Under the ‘2023 Nuclear Global Researcher Training Program for the Back-end Nuclear Fuel Cycle,’ supported by KONICOF, several experiments were conducted at IMRAM (Institute of Multidisciplinary Research for Advanced Materials) at Tohoku University. First, the recovery ratio of uranium was analyzed during the synthesis of uranyl nitrate by dissolving the actual radioisotope, U3O8, in a nitric acid solution. Second, thermogravimetric-differential thermal analysis (TG-DTA) of uranyl nitrate (UO2(NO3)2) and hyper-stoichiometric uranium dioxide (UO2+X) was performed. The enthalpy change was discussed to confirm the mechanism of thermal decomposition of uranyl nitrate under heating conditions and to determine the chemical hydrate form of uranyl nitrate. In the case of UO2+X, the value of ‘x’ was determined through the calculation of weight change data, and the initial form was verified using the phase diagram for the U-O system. Finally, the formation of a few UO2+X compounds was observed with heat treatment of uranyl nitrate and uranium dioxide at different temperature intervals (450°C-600°C). As a result of these studies, a deeper understanding of the thermal and chemical behavior of uranium compounds was achieved. This knowledge is vital for improving the efficiency and safety of nuclear fuel cycle processes and contributes to advancements in nuclear science and technology.

Once discharged, spent nuclear fuel undergoes an initial cooling process within deactivation pools situated at the reactor site. This cooling step is crucial for reducing the fuel’s temperature. Once the heat has sufficiently diminished, two viable options emerge: reprocessing or interim storage. A method known as PUREX, for aqueous nuclear reprocessing, involves a chemical procedure aimed at separating uranium and plutonium from the spent nuclear fuel. This separation not only minimizes waste volume but also facilitates the reuse of the extracted materials as fuel for nuclear reactors. The transformation of uranium oxides through dissolution in nitric acid followed by drying results in uranium taking the form of UO2(NO3)2 + 6H2O, which can then be converted into various solid-state configurations through different heat treatments. This study specifically focuses on investigating the phase transitions of artificially synthesized UO2(NO3)2 + 6H2O subjected to heat treatment at various temperatures (450, 500, 550, 600°C) using X-ray Diffraction (XRD) analysis. Heat treatments were also conducted on UO2 to analyze its phase transformations. Additionally, the study utilized XRD analysis on an unidentified oxidized uranium oxide, UO2+X, and employed lattice parameters and Bragg’s law to ascertain the oxidation state of the unknown sample. To synthesize UO2(NO3)2 + 6H2O, U3O8 powder is first dissolved in a 20% HNO3 solution. The solid UO2(NO3)2 + 6H2O is obtained after drying on a hotplate and is subsequently subjected to heat treatment at temperatures of 450, 500, 550, and 600°C. As the heat treatment temperature increases, the color of the samples transitions from orange to dark green, indicating the formation of different phases at different temperatures. XRD analysis confirms that uranyl nitrate, when heattreated at 500 and 550°C, oxidizes to UO3, while the sample subjected to 600°C heat treatment transforms into U3O8 due to the higher temperature. All samples exhibit sharp crystal peaks in their XRD spectra, except for the one heat-treated at 450°C. In the second experiment, the XRD spectra of the heat-treated UO2 consistently indicate the presence of U3O8 rather than UO3, regardless of the temperature. Under an oxidizing atmosphere within a temperature range of 300 to 700°C, UO2 can be oxidized to form U3O8. In the final experiment, the oxidation state of the unknown UO2+X was determined using Bragg’s law and lattice parameters, revealing that it was a material in which UO2 had been oxidized, resulting in an oxidation state of UO2.24.

In electric vehicles, the core is a secondary cell battery. Raw material is pulverized by the grinding disc in the Classifier Separator Mill (CSM) and rises through the Classifier Wheel. Both require characteristics to withstand high-speed rotation, including abrasion, corrosion, and shock. Our study analyzes the impact of RPM and heat source on temperature, convergence, and durability. In conclusion, high heat increases flow, while high RPM reduces the maximum temperature but may harm durability. Proper RPM settings enhance durability.

Hydrogen is considered as one of the most promising future energy carriers due to its noteworthy advantages of renewable and high calorific value. The long-term storage of liquid hydrogen with low heat leakage is essential for future deep space exploration. Because of low critical temperature and volatility, liquid hydrogen tank poses severe requirements to multi-layer insulation (MLI). In order to reduce heat leak into tank, vapor cooled shield (VCS) was set up to cool MLI by retrieving the heat of discharged cryogenic gas hydrogen. This paper presents an parametric study on insulation system in liquid hydrogen storage vessel with MLI and VCS. Thermal model was developed, and heat transfer analysis by varying VCS position was conducted. Temperature and heat flux distributions along time passing were derived, and effect of VCS position on insulation performance was investigated.

본 연구에서는 육계사에 차열 페인트와 히트펌프의 적용에 따른 내부 온도 변화를 분석 하였다. 이를 위하여 환기율, 환기 방법, 시간별 환기 변화에 따른 실험 조건을 설정하였으며 육 계사 외부 및 내부 기온을 측정하였다. 그 결과, 차열 페인트를 도포한 육계사에서는 최대 1－2°C 실내 기온 상승을 억제하 는 효과가 나타났으며 히트펌프를 가동한 육계사에서는 외기 온도의 영향을 제일 적게 받는 환기율 0%일 때 내부 기온 감소 가 제일 크게 나타났다. 계사 내부의 온도가 외기 온도보다 높 을 경우에는 환기율을 높게 설정하여 환기팬을 이용한 냉방이 더욱 효과적이나 계사 내부 온도가 외기 온도와 유사하거나 낮을 경우에는 히트펌프를 이용하는 것이 가장 효과적일 것으 로 판단된다. 히트펌프 가동 시 외기 온도의 영향이 적은 환기 율을 0%로 설정하였을 때 내부 기온이 가장 큰 폭으로 감소하 였으나 실제 육계사에서는 분진, 이물질, 암모니아 등을 고려 하여 최소환기율 정도로 환기율을 설정한 후 히트펌프를 가동 하는 것이 가장 효율적일 것으로 판단된다. 본 연구는 실험 기 간이 짧아 데이터가 많지 않으며 실제 육계가 사육되고 있는 환경에서 실험을 진행한 것이 아니라는 한계가 있다. 향후 후 속 연구로 실제 닭이 사육되고 있는 환경에서의 히트펌프 효 과 분석과 히트펌프의 전력사용량, 냉방부하, 환기팬 가동시 간 등 다양한 환경인자를 포함한 연구가 진행되어야 할 것으 로 판단된다.

현재, 국내에서는 가공식품인 식용유지에 대한 잔류농약 허용기준이 설정되어 있지 않아 잔류농약은 식용유 품질평 가의 사각지대라 할 수 있다. 본 연구에서는 식용유지에서 가열증류법을 이용하여 68종의 농약을 대상으로 추출 및 정 제법을 최적화하여 GC-MS/MS 분석법을 확립하였다. 가열 증류법은 가열온도 및 시간의 영향을 받았으며 이동상의 역 할을 하는 질소의 유량과 용출용매의 종류에는 큰 영향을 받지 않는 것으로 나타났다. 본 연구에서 잔류농약의 결정 계수(R2)는 0.99 이상으로 나타났고, 정량한계(LOQ)는 0.01- 0.02 mg/L이었으며, 대두유를 이용하여 0.01, 0.02, 0.1, 0.5 mg/L 수준으로 회수율 실험 결과 평균 회수율(n=5)은 66.1- 120.0%이었고 상대표준편차는 ±10%이하로 나타났다. 또한 실험실내 일간정밀도는 11%이하로 조사되어, 식품의약품안 전평가원의 ‘식품등 시험법 마련 표준절차에 관한 가이드라 인(2016)’에 적합한 수준임을 확인하였다. 따라서 본 연구에 서 개발한 시험법은 식용유지의 잔류농약 안전관리를 위한 시험법으로 활용이 가능할 것으로 기대된다.

Nowadays, transferred type arc plasma torches have been widely present in industrial applications, in particular, using melting pool of electrically conducting materials such as arc furnace, welding and volume reduction of radioactive wastes. In these applications, the melting pools are normally employed as an anode, thus, heat flux distributions on anode melting pool need to be characterized for optimum design of melting pool system. For this purpose, we revisited the one-dimensional model of the anode boundary layer of arcs and solved governing equations numerically by using Runge-Kutta method. In addition, the direct melting process of non-combustible wastes in the crucibles were discussed with the calculation results.

This study deals with the maximum thermal load analysis and optimal capacity determination method of tank culture system for applying seawater source heat pump to save energy and realize zero energy. The location of the fish farm was divided into four sea areas, and the heat load in summer and winter was analyzed, respectively. In addition, two representative methods, the flow-through aquaculture system and the recirculation aquaculture system were reviewed as water treatment methods for fish farms. In addition, the concept of the exchange rate was introduced to obtain the maximum heat load of the fish farms. Finally, power consumption for heat pumps was analyzed in the view point of sea areas, tank capacity, and exchange rate based on the calculated maximum thermal load.

In this study, we performed thermal safety design of the electric module of a heat-loaded equipment with consideration of its heat dissipation performance. Initially, we calculated the heat dissipation of natural convection to choose a cooling method. Based on this, we found that some modules required forced convection and selected an air-cooling method with an outdoor temperature of 43 degrees Celsius, which is the maximum temperature in Korea. Prior to module production, we performed thermal analysis of each module and proceeded with a design to increase the thermal conductivity of the module as a primary step, and subsequently proceeded with Heat Sink design to maximize the heat dissipation performance. After considering various constraints according to the system requirements and designing the cooling path, we experimentally and analytically secured thermal safety at the operating temperature of the equipment.

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.