• Journal of the Korea Academia-Industrial cooperation Society
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• 제22권6호
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• pp.460-468
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• 2021

This study investigated the enhanced combustion efficiency of an "air-cooled combustion system" with single F.D. fan, and performed a numerical analysis for the operation and design conditions to increase the combustion efficiency. The combustion efficiency in an actual combustor was compared before and after the structure modification. Numerical analysis for application of a single fan revealed the difficulty of forming a turbulence for circular combustion conditions. This is because the supply ratio of combustion air supplied into 2 flow paths becomes irregular in the combustion furnace due to a change in friction force and pressure in each flow path. Subsequently, two methods of supplying air into the combustion furnace were analyzed numerically to obtain the optimal combustion conditions of an air-cooled combustion system. The first method involved injecting the preheated combustion air after a 180~360 degree rotation from the outer wall, whereas in the second method, the combustion air was injected into the combustion furnace in a tangential direction after primary heat exchange outside the combustion furnace, by applying a rotatable vane structure in the combustion furnace. Results reveal that application of a single F.D. fan to the air injection into a rotatable combustion furnace is desirable for optimization of the combustion conditions for applying a duct structure having a dual cooling wall for the cooling of the outer wall of the combustion furnace, and for maintaining perfect mixing in the combustion furnace. We therefore confirmed enhanced combustion efficiency by comparing the actual combustion efficiency before and after structure modification.

• Journal of Advanced Navigation Technology
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• 제22권2호
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• pp.76-83
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• 2018

In order to prevent overusing the fishing gear and to reduce discarded fishing gear, there is a need for a technique that can efficiently transmit the information including the type and location of the fishing gear and the user's real name to the fishing boat and the control center using IoT-based communication. In order to do this, it is necessary to be able to confirm the position information of a plurality of buoys that can be identified by the base stations on the land. In this paper, in order to service the maritime IoT communication system, we calculate the link budget between the land base station and the targets on the sea to derive the service coverage. To design a marine IoT radio network for building a fishing gear monitoring system, we calculate link budget for wireless service optimization at sea for NB-IoT using 1.8 GHz frequency band and LoRa service using 900 MHz frequency band. In addition, the link budget between the land base station and buoy, the link budget between the land base station and fishing boat are calculated and the results are analyzed.

• Applied Chemistry for Engineering
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• 제22권2호
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• pp.161-166
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• 2011

The $CO_2$ dry reforming reaction, which converts carbon dioxide to hydrogen and carbon monoxide, is typical endothermic reaction, and also known as adverse reaction owing to thermodynamics. In order to overcome the problem, the development studies of suitable catalyst based on precious metals for high durability of thermal and optimization of life time have been examined but it had economical problem by high cost. In this study, we confirmed optimum contents of Pt and La with such different contents of Pt (0.02~0.2 wt%) or La (2~20 wt%) over $Co/SiO_2$ which prepared for excellent activity and cost-effective catalysts. As a result, the promoted catalysts with 0.04 wt% Pt or 9 wt% La over $Co/SiO_2$ showed the highest activity which is 57% and 55% $CO_2$ conversion respectively. Also, the particle size of cobalt on the promoted catalysts with 0.04 wt% Pt or 9 wt% La by characterization of catalyst could confirm the smallest particle size in this study. Therefore, it could know that particle size of cobalt had effected the stability and reactivity of catalysts due to the contents of Pt and La.

• Journal of Communication Design
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• 제65권
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• pp.530-538
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• 2018

Recently, museums are attracting the attention of visitors and society. However, research on museum interpretation conducted at domestic and foreign is relatively limited. The plan design of the museum commentary system was mainly based on the perspective of the experts, and most of them do not reflect the desire of the visitors. This study focused on visitors' experience of using museum Interpretation system. Through analyzing the effect of the Interpretation system of the museum that the visitor feels, we examined whether the Interpretation system of the museum meets the cultural needs of the visitors and identified the problems and deficiencies in the system. After that, the problems were rearranged and suggested the main elements of the commentary system of the museum finally, so as to help improve the museum commentary system and the educational function.In the first part of the study, the four major explanatory methods existing in the museum were confirmed. After that, we conducted in - depth interviews on four types of commentary methods and collected existing problems and deficiencies. The results of the type analysis were grouped into 14 types and the questionnaire was used to conduct a general survey on 14 problems. In this study, the user 's discomfort and problems were identified in the museum Interpretation system, and based on this, five key elements necessary for the museum Interpretation system were derived. Among them, inhalation is the weakest element in the museum commentary system, and future research will be conducted on how to apply each factor. I hope that you will be a reference material when you carry out research on the optimization of the Interpretation system of the museum and the improvement of the Interpretation experience.

• Electronic Materials Letters
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• 제14권6호
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• pp.718-724
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• 2018

With the development of photovoltaic industry, the cost of photovoltaic power generation has become the significant issue. And the metallization process has decided the cost of original materials and photovoltaic efficiency of the solar cells. Nowadays, double printing process has been introduced instead of one-step printing process for front contact of polycrystalline silicon solar cells, which can effectively improve the photovoltaic conversion efficiency of silicon solar cells. Here, the relative cheap Cu paste has replaced the expensive Ag paste to form Ag/Cu composite front contact of silicon solar cells. The photovoltaic performance and the cost of photovoltaic power generation have been investigated. With the optimization on structure and height of Cu finger layer for Ag/Cu composite double-printed front contact, the silicon solar cells have exhibited a photovoltaic conversion efficiency of 18.41%, which has reduced 3.42 cent per Watt for the cost of photovoltaic power generation.

• Applied Chemistry for Engineering
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• 제32권3호
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• pp.326-331
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• 2021

In this study, the preparation conditions for a TiO₂-based vanadium-based catalyst for oxidizing hydrogen sulfide at room temperature were optimized. Four types of commercial TiO₂ were used as a catalyst support and the performance evaluation of hydrogen sulfide oxidation at room temperature of V/TiO₂ by varying vanadium contents prepared using the impregnation method was performed. Among the types of TiO₂ tested, it was confirmed that the catalyst with the vanadium content of 5% and based on TiO₂(A) has the best hydrogen sulfide conversion rate of 58%. By comparing the physical and chemical properties of the catalyst, the specific surface area of the support and the species of dominant vanadium are the major factor in catalyst performance. In order to confirm the regeneration characteristics of the catalyst with reduced activity, heat treatment was performed at 400 ℃ for 2 h, and the amount of hydrogen sulfide oxidation decreased by 10% due to the partial deposition of sulfur in the regenerated catalyst, but it was confirmed that the initial performance was similar.

• Environmental and Resource Economics Review
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• 제30권2호
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• pp.237-268
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• 2021

As variable renewable sources rapidly increase due to the Energy Transition plan, integration cost of renewable sources to the power system is rising sharply. The increase in variable renewable energy reduces the capacity factor of existing traditional power capacity, and this undermines the efficiency of the overall power supply, and demand resources are drawing attention as a solution. In this study, we analyzed how much electric vehicle demand resouces, which has great potential among other demand resources, can reduce power supply costs if it is used as a flexible resource for renewable generation. As a methodology, a stochastic form of power system optimization model that can effectively reflect the volatile characteristics of renewable generation is used to analyze the cost induced by renewable energy and the benefits offered by electric vehicle demand resources. The result shows that virtual power plant-based direct control method has higher benefits than the time-of-use tariff, and the higher the proportion of renewable energy is in the power system, the higher the benefits of electric vehicle demand resources are. The net benefit after considering commission fee for aggregators and battery wear-and-tear costs was estimated as 67% to 85% of monthly average fuel cost under virtual power plant with V2G capability, and this shows that a sufficient incentive for market participation can be offered when a rate system is applied in which these net benefits of demand resources are effectively distributed to consumers.

• Journal of the Korean Society of Radiology
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• 제15권3호
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• pp.355-359
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• 2021

In this study, the purpose of this study was to analyze the degree of exposure of radiation workers assigned to the Department of Radiology and frequent visitors during on-campus practice, and to conduct a basic study on the feasibility and optimization of the radiation protection of the Nuclear Safety Act for the Department of Radiology. . The average exposure dose of occupational workers by year was 0.01 mSv, the lowest in 2014 and 2016. The highest figure was 0.12 mSv in 2018. The average exposure dose of frequent visitors by year was the lowest at 0.013 mSv in 2018, and the highest at 0.022 mSv in 2016. According to this study, the annual exposure dose received by professors, practical assistants, and students in the department of radiology (department) who use only radiation generators in the course of in-school practice is less than 1 mSv, which is the dose limit for the general public. Therefore, at the time when the radiation dose of students in the Department of Radiology is lower than the dose limit of the general public, the current safety regulation of the Nuclear Safety law is judged to be excessive regulation. Therefore, it is considered necessary to revise the regulations for radiation generators in the current Nuclear Safety law or to revise the radiation safety management system for university students.

• Journal of Korea Water Resources Association
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• 제54권2호
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• pp.105-119
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• 2021

An increase in the frequency and intensity of both floods and droughts has been recently observed due to an increase in climate variability. Especially, land-use change associated with industrial structure and urbanization has led to an imbalance between water supply and demand, acting as a constraint in water resource management. Accurate rainfall-runoff analysis plays a critical role in evaluating water availability in the water budget analysis. This study aimed to explore various continuous rainfall-runoff models over the Soyanggang dam watershed. Moreover, the ensemble modeling framework combining multiple models was introduced to present scenarios on streamflow considering uncertainties. In the ensemble modeling framework, rainfall-runoff models with fewer parameters are generally preferred for effective regionalization. In this study, more than 40 continuous rainfall-runoff models were applied to the Soyanggang dam watershed, and nine rainfall-runoff models were primarily selected using different goodness-of-fit measures. This study confirmed that the ensemble model showed better performance than the individual model over different flow regimes.

• Korean Journal of Food Science and Technology
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• 제53권1호
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• pp.29-33
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• 2021

The fish cake industry is attempting to overcome the standstill by adopting new production technologies, such as 3D printing technology. The characteristics of food 3D printing ink, including viscosity, hardness, and adhesiveness, are essential in food 3D printing technology. Therefore, in this study, the effect of salt on the gelation of surimi 3D ink and its texture for 3D printing were examined. After adding salt (1-4%) to fish meat, the viscosity and adhesiveness of fish meat was found to be increased by gelation. Among the fish surimi with various salt contents, surimi with 3% salt showed the most suitable characteristics, including viscosity, adhesiveness, and hardness, for a whirlwind and λ 3D printing model. Scanning electron microscopy showed that the addition of 3% salt resulted in the most adhesive surimi and less porous spaces. Overall, our study found that 3% salt would be suitable for 3D printing ink using fish surimi.