• Proceedings of the Korean Institute of Building Construction Conference
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• 2021.11a
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• pp.158-159
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• 2021

When the porous concrete is exposed to the external environment, the internal relative humidity changes from time to time due to the inflow and outflow of moisture. This change in moisture is affected by temperature. The temperature and humidity of concrete is dominant in the carbonation rate, the largest cause of deterioration of concrete. In this study, actual weather data were used as boundary conditions. A carbonization model of concrete temperature and humidity and calcium hydroxide was constructed to perform long-term analysis. There is a slight error in the carbonation formula of the Japanese Academy of Architecture applying the Kishtani coefficient, a representative experimental formula related to carbonization, and the analysis result values. However, considering that it behaves very similarly, it is thought that a fairly reliable numerical analysis model has been established. A slight error is believed to be due to the fact that the amount of residual calcium hydroxide in the carbonated site has not yet been clearly identified.

• Journal of Internet of Things and Convergence
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• v.10 no.2
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• pp.125-130
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• 2024

With the rapid growth of mobility technology, the industrial sector is demanding storage devices that can reliably process data from various equipment and sensors in vehicles. NAND flash memory is being utilized as a storage device in mobility environments because it has the advantages of low power and fast data processing speed as well as strong external shock resistance. However, flash memory is characterized by data corruption due to long-term exposure to high temperatures. Therefore, a dedicated system for temperature management is required in mobility environments where high temperature exposure due to weather or external heat sources such as solar radiation is frequent. This paper designs a dedicated temperature management system for managing storage device temperature in a mobility environment. The designed temperature management system is a hybrid of traditional air cooling and water cooling technologies. The cooling method is designed to operate adaptively according to the temperature of the storage device, and it is designed not to operate when the temperature step is low to improve energy efficiency. Finally, experiments were conducted to analyze the temperature difference between each cooling method and different heat dissipation materials, proving that the temperature management policy is effective in maintaining performance.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.34 no.3
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• pp.325-331
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• 2010

Three-cup anemometers are popular devices for measuring wind speeds in automated weather stations, environmental monitoring systems, and wind turbines. Cup anemometers usually suffer from lack of long-term stability owing to the wear of the bearing systems that support the rotational parts. The bearing systems are susceptible to external pollutants, vibrations, and gusts. Therefore, these anemometers have to be calibrated regularly to maintain the desired characteristics for measuring wind speed. In the present study, a new in-situ calibration system to help reduce cost and save time by calibrating the cup anemometers at the installation site is proposed. A portable in-situ calibrator was fabricated. After the characteristics of this calibrator were verified, it was used to calibrate cup anemometers. Some of the calibration results were compared with the data obtained by wind tunnel testing.

• Journal of The Korean Society of Agricultural Engineers
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• v.65 no.1
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• pp.41-49
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• 2023

To utilize the hydraulic and hydrological models when simulating floods in agricultural watersheds, it is necessary to consider agricultural reservoirs, farmland, and farmland drainage system, which are characteristics of agricultural watersheds. However, most of them are developed individually by different researchers, also, each model has a different simulation scope, so it is hard to use them integrally. As a result, there is a need to link each hydraulic and hydrological model. Therefore, this study established an integrated flood simulation system for the comprehensive flood simulation of agricultural reservoir watersheds. The system can be applied easily to various watersheds because historical weather data and the SSP (Shared Socio-economic Pathways) climate change scenario database of ninety weather stations were built-in. Individual hydraulic and hydrological models were coded and coupled through Python. The system consists of multiplicative random cascade model, Clark unit hydrograph model, frequency analysis model, HEC-5 (Hydrologic Engineering Center-5), HEC-RAS (Hydrologic Engineering Center-River Analysis System), and farmland drainage simulation model. In the case of external models with limitations in conceptualization, such as HEC-5 and HEC-RAS, the python interpreter approaches the operating system and gives commands to run the models. All models except two are built based on the logical concept.

• Journal of the Korean Society of Marine Environment & Safety
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• v.24 no.6
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• pp.646-653
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• 2018

Marine accidents caused by dragging anchors occur constantly due to enlargement of ships' size and unusual weather conditions. Nevertheless, vessel operators rely on their experience because the calculations of actual holding power and external forces are complex and inconvenient. The purpose of this study was to propose a program for the anchor dragging risk assessment in order to provide crew and VTSO with the information to determine easily the danger of dragging and take appropriate action. The input data in this program were composed of the ship's basic particulars, anchoring condition, and external environment etc. on calculating for the wind pressure, frictional force, drift force, and holding power. Three dragging anchor accidents were applied to the program's data input at the time of the day, then the result was assessed by 'warning', which was verified with a high confidence. As a result, the risk of dragging anchors can be predicted in advance through this program. In further studies, it is necessary to simplify the input data and improve user convenience through automatic input from various equipment.

• Journal of the Architectural Institute of Korea Planning & Design
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• v.35 no.8
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• pp.23-34
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• 2019

The façade, a fundamental function as a skin that protects human life from external environment such as cold and hot weather, snow, rain, and wind, etc, has served as a media for communication between indoor space of the building and outside space. From the media for communication point of view, the approach to envelope design, in which environmental elements are transmitted internally through the filtering of external environments, has been evolving in various ways from the past to the present. Today, modern architecture technologies including curtain wall systems and user-friendly computer programming and environmental analysis programs demonstrate a differentiated approach to envelope design related to the indoor environment. For this reason, it is worth noting that the envelope design factors and trends that appear variously in the UNStudio's projects before and after the 2000s. The factors reflected in the envelop design in conjunction with the indoor environment obtained through the case study of the UNStudio's office projects were daylight environment, thermal environment, ventilation, noise, privacy and view, and consideration for daylight environment and thermal environment was reflected in many cases through the case study. Looking at the changes in the diagrams in order of year, it can be seen that the envelope design using the environmental analysis tool has been performed since 2006. This is a clue to show the envelop design changes from the conceptual method to the data-based one. The diagrams and analysis results related to the envelop design showed that the thermal environment related to solar radiation was the most, and no diagrams and analysis related to the indoor illumination were found. Since 2010, PV panel installation has been shown in the envelope design, which can be found in the increased efficiency of PV panels due to the technological advances and the decrease in production cost.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2002.11a
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• pp.560-565
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• 2002

In this paper, we implemented the sign board system that displays user's image, user's sentence, the information from DARC an[1 information based position by GPS module for vehicle. The existing sign board is displaying only user's image and sentence. Or other existing sign board is displaying the information via CDMA network. However, our system is also able to display the user's message like other system and gain the information more cheap by DARC. This system consists of 6 parts. The DARC control part classes the DARC information - news, weather, stock and time. The GPS control part gains moment and item to display with calculating the information of global position, direction, speed and satellite. The LED control part has two buffers to store and handle the image. The buffers help the system display various effected images on LED board. An external memory card includes the location based data, the option file and the displayed data files. The data files are stored by FAT 16 with the folder structure on external memory card. The USB controls the communication with PC. PC programs can control and monitor this system. This system is using G72l voice file format, for casting the information. This system was established at the vehicle and we monitored this system. The system displayed the DARC data , user's data and the location based data on the LED board, successfully.

• Journal of Urban Science
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• v.8 no.1
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• pp.25-31
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• 2019

Infiltration affects indoor environmental and air quality and energy consumptions in buildings. Especially, airflow and the infiltration are more remarkable in high-rise buildings due to the air-driving forces (stack and wind effects). Thus, it is important to understand infiltration distributions in high-rise residential buildings. In this study, the weather-driven infiltration is characterized from the viewpoint of interactions between external wind and stack effect in high-rise residential buildings. To calculate accurately the annual infiltration distributions, this study also suggests an airflow and thermal simulation method with a two-step calibration of air-leakage data. The simulated results show (1) how the interaction between stack and wind effects induce infiltration types (outdoor and interzone air infiltration) and (2) how much the interzone air infiltration (being ignored in previous studies) occurs due to the stack effect, as well as the outdoor air infiltration rates.

• Journal of the Architectural Institute of Korea Structure & Construction
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• v.35 no.8
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• pp.177-184
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• 2019

Recently, electric power usages and peak loads from buildings are increasing due to higher outdoor air temperatures and/or abnormal climate during the summer period. As one of the eco-friendly measures, a renewable energy system has been received much attention. Particularly, interest on a photovoltaic (PV) system using solar energy has been rapidly increasing in a building sector due to its broad applicability. In using the PV system, one of important factors is the PV efficiency. The normal PV efficiency is determined based on the STC(Standard Test Condition) and the NOCT(Nominal Operating Cell Temperature) performance test. However, the actual PV efficiency is affected by the temperature change at the module surface. Especially, higher module temperatures generally reduce the PV efficiency, and it leads to less power generation from the PV system. Therefore, the analysis of the relation between the module temperature and PV efficiency is required to evaluate the PV performance during the summer period. This study investigates existing algorithms for calculating module surface temperatures and analyzes resultant errors with the algorithms by comparing the measured module temperatures.

• The Magazine of the Society of Air-Conditioning and Refrigerating Engineers of Korea
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• v.11 no.4
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• pp.6-18
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• 1982

The performance of two typical types of solar hot water heating system was tested in Seoul. Types of systems studied are single-tank internal external heat exchanger system and single-tank internal heat exchanger system. Comparing to experimental results, a transient system simulation program was made to analyze the performance of the selected system. The climate data, Standard Weather Year for Seoul, required for the simulation was provided. Computer simulations were used to estimate the effect of significant parameters upon system performance. The followings are obtained. 1. In the domestic solar water Heating system, the value $20-40kg/m^2\;h$ for flow rate through the collector is much better than the recommended value $72kg/m^2\;h$ in the solar heating system. 2. The effectiveness of collector heat exchanger and storage tank size are found to have only a small effect upon system performance. 3. The hot water draw pattern has a significant effect on system performance. A higher system efficiency achieved when draw-off occurred around noon than when it occurred around early morning. Using the above results, the reference solar hot water system which provides $300\ell$ of hot water per day, was selected as a guide for designer. And simplified graphical method was developed based on the modified f-chart method to determine required collector area. When the system design parameters of the proposed system differs from the reference system, required collector area can be calculated from area adjustment factors.