• Journal of the Korean Society for Heat Treatment
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• v.35 no.3
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• pp.121-129
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• 2022

Recently the growth of the renewable energy production has caused the flexible operation in LNG combined cycle power plant. Due to the rapid start and stop operations, large CrMoV castings used for turbine casings and valve bodies could be distorted and lead to replacement or welding repair. This study was performed to find out the characteristics of the repair welding for a damaged CrMoV casting steel. A typical field repair method (arc & TIG welding) was applied to making specimens. The degraded N2 packing head sample from the steam turbine was used. The evaluations of weldments were carried out in terms of microstructural characterization, microhardness measurements, tensile, creep-rupture and fatigue tests. Color etching was also applied for better understanding of welding microstructures. As the boundary between HAZ and base material was deteriorated by welding, it caused microstructural changes formed during PWHT and the shortening of the remaining residual life. By comparing the properties according to repair welding method, it was possible to derive what important welding factors were. As a result, arc welding method is more suitable for repair welding on CrMoV castings.

• Journal of architectural history
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• v.31 no.1
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• pp.7-17
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• 2022

The purpose of this thesis is to understand the shape of The Sijeon (Licensed-Markets) established around the Jongno and Namdaemun-ro Avenues in Hanyang during the Joseon Dynasty in the 19th and 20th centuries and then to examine the relationship with the urban structures of Hanyang City. By investigating the excavation results of the Cheongjin and Gongpyeong areas, drawings, photos, and documentary records related to the city, this study classified the building types in the Jonggak area. As a result, since the 19th century, the basic form of Sijeon with 2 Gan(間, bay) in the front facade and 3 Gan(間) on the side, in other words, 5M in the front and 8M in the side was arranged in parallel, and it was a type with a corridor-type courtyard inside. The inner sides of Jongno Avenue had an atypical flat shape that suited the more free lot, and a courtyard-type plan with a single entrance was also confirmed in the one or two Bang(房, district). This study reflected the operation method of the Sijeon buildings b between the one unit and the other units, which affected the internal spatial structures, and it found that the size and style of the Sijeon buildings were closely relevant to the size of the lots near Jongno Avenue.

• Journal of Software Assessment and Valuation
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• v.16 no.2
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• pp.109-115
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• 2020

In this paper, the problem that occurs when negative voltage is generated using an inexpensive buck device in an IT device that is supplied with a single power by an adapter or battery is analyzed. For the cause analysis, the principle of operation of the buck device and the principle of the inverter circuit were examined, and the circuit characteristics of the inverter circuit were analyzed using the buck device. As a result of the analysis, it was confirmed that the inverter circuit using the buck device initially needs a large starting current, and in particular, in the case of a current capacity that is less than the starting current in the circuit that supplies power, it was confirmed that it could fall into a state similar to the latch-up phenomenon. In order to confirm the analysis result, an experimental circuit was constructed and the input current was checked. If the supply current is sufficient, it is confirmed that over-current flows and starts. If the supply current is insufficient, the circuit cannot start and a latch-up phenomenon occurs.

• Journal of People, Plants, and Environment
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• v.24 no.4
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• pp.329-339
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• 2021

Background and objective: This study was conducted to obtain empirical data for deriving necessary items for the creation and management of gardens in urban agricultural parks while maintaining the publicness of the place by examining the difference in perception among park visitors about the gardens in the public parks. Methods: A survey was conducted on users of urban agricultural parks in 6 locations and 113 copies of the questionnaire were collected. After understanding the demographic characteristics and the current use of the garden, we identified the importance of the necessary items for the public gardens. Results: 108 subjects(95.6%) responded that gardens are needed in urban parks, for psychological and emotional health (26.2%) and for interaction and friendship with family and neighbors(23.2%). For use of garden crops, most were private sales(96 subjects, 64.4%), and both sales preferred to partially donate their crops. Most used communal gardens operated by public institutions(30.1%). It was found that 96.4% of the respondents were satisfied with gardening activities, and 107(94.7%) of them showed their intention to participate in the gardening in the future. The Kaiser Meyer Olkin value was .848 and the significance level was .001, proving the validity of factor analysis. The factors were named composition elements(Factor 1), management items(Factor 2), convenience elements(Factor 3), and operational facilities(Factor 4). In the survey on the creation and management of gardens in urban agricultural parks, there were no statistically significant differences, but all items had correlations. Conclusion: The results have reflected the needs of actual users in establishing the plans to operate urban gardens, thereby having great utility value as the basic data for continuous garden management. Further research can be conducted to derive detailed elements that can guarantee sustainability of urban gardens and suggest high-quality data for management of gardens in urban agricultural parks.

• Journal of the Korea Society of Computer and Information
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• v.27 no.12
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• pp.171-178
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• 2022

In this paper, we propose a classification method according to the type and characteristics of stablecoins for risk analysis, and analyze the risk factors of each stablecoin based on this classification. First, this paper explains the technologies and ecosystem of blockchain and decentralized finance(DeFi) to understand stablecoins. In addition, the operation principle of the major stablecoins currently released and used is explained for each proposed classification type. Based on this, the risk type and risk factors of each stablecoin are derived. The risk types proposed in this paper are classified as defegging, liquidation, and exploit, and the risk factors are classified as depegging due to reliability of operator, depegging due to reliability of algorithm, depegging due to failure of algorithm, liquidation due to high volatilty and oracle attack. Based on the proposed classification, we analyze the risk factors of major stablecoins currently circulating in the crypto market.

• Journal of the Korean Society of Industry Convergence
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• v.25 no.6_3
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• pp.1147-1154
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• 2022

Now that the development of autonomous driving is progressing, LiDAR has become an indispensable element. However, LiDAR is a device that uses lasers, and laser side effects may occur. One of them is the much-talked-about eye-safety, and developers have been satisfying this through laser characteristics and operation methods. But eye-safety is just one of the problems lasers pose. For example, irradiating a laser with a specific energy level or higher in a dusty environment can cause deterioration of the dust particles, leading to a sudden explosion. For this reason, the dust ignition proof regulations clearly state that "a source with a pulse period of less than 5 seconds is considered a continuous light source, and the average energy does not exceed 5 mJ/mm 2 or 35 mW" [2]. Energy of output optical power is limited by the law. In this way, the manufacturer cannot define the usage environment of the LiDAR, and the development of a LiDAR that can be used in such an environment can increase the ripple effect in terms of use in application fields using the LiDAR. In this paper, we develop a LiDAR with low optical power that can be used in environments where high power lasers can cause problems, evaluate its performance. Also, we discuss and present one of the directions for the development of LiDAR with laser power limited by dust ignition proof regulations.

• Journal of the Korean Society of Marine Environment & Safety
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• v.28 no.6
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• pp.992-1001
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• 2022

The maritime traffic analysis has been conducted in various ways to solve problems arising from the complex marine environment. However, recent trends in the maritime industry, such as the development of the maritime autonomous surface ships (MASS), suggest that maritime traf ic analysis needs change. Accordingly, based on the studies conducted over the past decade for improvements, automatic identification system (AIS) data is mainly used for maritime traffic analysis. Moreover, the use of geographic information that directly af ects ship operation is relatively insufficient. Therefore, this study presented a method of using a combination of shape format data and AIS data to enhance maritime traffic analysis in preparation for the commercialization of autonomous ships. Consequently, extractable marine traffic characteristics were presented when shape format data were used for marine traffic analysis. This is expected to be used for marine traffic analysis for the introduction of autonomous ships in the future.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.25 no.12
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• pp.1846-1852
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• 2021

In modern society, various digital devices are being distributed in a wide range of fields due to the fourth industrial revolution and the development of IoT technology. However, noise is generated in the process of acquiring or transmitting an image, and not only damages the information, but also affects the system, causing errors and incorrect operation. AWGN is a representative noise among image noise. As a method for removing noise, prior research has been conducted, and among them, AF, A-TMF, and MF are the representative methods. Existing filters have a disadvantage that smoothing occurs in areas with high frequency components because it is difficult to consider the characteristics of images. Therefore, the proposed algorithm calculates the standard deviation distribution to effectively eliminate noise even in the high frequency domain, and then calculates the final output by applying the probability density function weight of the Laplace distribution using the curve fitting method.

• The Journal of the Convergence on Culture Technology
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• v.8 no.6
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• pp.135-140
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• 2022

In this study, we conducted a care farm program that is currently being operated as a pilot in a care farm in Korea, interviewed the experiences and feelings of dementia patients who experienced this as a patient care-giver, and confirmed the strengths and weaknesses of the care farm program. Accordingly, we investigated the points for improvement and the characteristics of the program in the care farm program and operation. In particular, opinions are gathered on the use of a care farm in the early stages of dementia, accessibility issues from residence to the care farm, continuity of various programs and programs, and development of seasonal content. In order to develop a program related to care agriculture for dementia patients by using healing agriculture in future care farms, it is necessary to consider factors such as use problems, accessibility, diversity, continuity, and seasonality of early dementia patients.

• Journal of the Korean Society for information Management
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• v.39 no.3
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• pp.133-163
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• 2022

This study aims to analyze the effect of marketing using Chinese public library WeChat official accounts on the perception of the library and loyalty. For this purpose, research possibilities were explored, and a questionnaire was developed through in-depth interviews with users who subscribed to the Chinese public library WeChat official accounts and those who did not. A survey was conducted with the questionnaire for public library users in six regions of China. As a result, it was confirmed that the characteristics of the official account operation had a positive effect on the perception of the libraries and users' loyalty. This study is meaningful in that it verified how Chinese public library marketing using SNS affected users' purpose on the use of libraries, perception of libraries, and users' loyalty, and suggested how to deal with WeChat official accounts among SNS types.