• Journal of the Korea Academia-Industrial cooperation Society
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• v.7 no.6
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• pp.1047-1055
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• 2006

We patterned nano-width lines on a super hard bulk diamond substrate by varying the ion beam current and ion beam sources with a dual beam field ion beam (FIB). In addition, we successfully fabricated two-dimensional nano patterns and three-dimensional nano plate modules. We prepared nano lines on a diamond and a silicon substrate at the beam condition of 30 kV, 10 pA $\sim$ 5 nA with $Ga^+$ ion and $H_2O$ assisted ion sources. We measured each of the line-width, line-depth, etched line profiles, etch rate, and aspect ratio, and then compared them. We confirmed that nano patterning was possible on both a bulk diamond and a silicon substrate. The etch rate of $H_2O$ source can be enhanced about two times than that of Ga source. The width of patterns on a diamond was smaller than that on a silicon substrate at the same ion beam power The sub-100 nm patterns on a diamond were made under the charge neutralization mode to prevent charge accumulation. We successfully made a two-dimensional, 240 nm-width text of the 300-lettered Lord's Prayer on a gem diamond with 30 kV-30 pA FIB. The patterned text image was readable with a scanning electron microscope. Moreover, three dimensional nano-thick plate module fabrication was made successfully with an FIB and a platinum deposition, and electron energy loss spectrum (EELS) analysis was easily performed with the prepared nano plate module.

• Journal of Digital Convergence
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• v.19 no.9
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• pp.189-199
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• 2021

In order to increase the self-reliance rate of new and renewable energy in order to respond to the mandatory domestic zero-energy buildings, the taller the building, the more limited the site area, and installing PV modules on the roof is not enough. Therefore, BIPV (Building integrated photovoltaic, hereinafter BIPV) is the industry receiving the most attention as a core energy source that can realize zero-energy buildings. Therefore, this study conducted a survey on the problems of the BIPV industry in a self-discussing method for experts with more than 10 years of experience of designers, builders, product manufacturers, and maintainers in order to suggest the right direction and revitalize the BIPV industry. Industrial problems of BIPV adjustment are drawn extention range of standard and certification for products, range improvement for current small condition of various kind productions, need to revise standards for capable of accomodating roof-type, color-module and louver-module, necessary of barrier in flow of foreign modules into korea through domestic certification mandatory, difficulty in obtaining BIPV information, request to prevent confusion among participants by exact guidelime about architectural application part of BIPV, and lack of the BIPV definition clearness, support policy, etc. Based on the improvements needed for the elements, giving change and competitiveness impacts aims to present and propose counter measures and direction.

• Journal of the Microelectronics and Packaging Society
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• v.27 no.4
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• pp.55-60
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• 2020

The PERC photovoltaic (PV) modules installed in PV power plant are still reports potential-induced degradation (PID) degradation due to high voltage potential differences. This is because Na+ ions in the cover glass of PV modules go through the encapsulant (EVA) and transferred to the surface of solar cells. As positive charges are accumulated at the ARC (SiOx/SiNx) interface where many defects are distributed, shunt-resistance (Rsh) is reduced. As a result, the leakage current is increased, and decrease in solar cell's power output. In this study, to prevent of this phenomenon, a Moth-eye nanostructure was deposited on the rear surface of an optical film using Nano-Imprint Lithography method, and a solar mini-module was constructed by inserting it between the cover glass and the EVA. To analyze the PID phenomenon, a cell-level PID acceleration test based on IEC 62804-1 standard was conducted. Also analyzed power output (Pmax), efficiency, and shunt resistance through Light I-V and Dark I-V. As a result, conventional solar cells were decreased by 6.3% from the initial efficiency of 19.76%, but the improved solar cells with the Moth-eye nanostructured optical film only decreased 0.6%, thereby preventing the PID phenomenon. As of Moth-eye nanostructured optical film, the transmittance was improved by 4%, and the solar module output was improved by 2.5%.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.22 no.5
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• pp.543-553
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• 2021

As a key policy for achieving the goal of reducing GHG in the building sector, Korea has enforced the mandatory certification of zero-energy buildings for new buildings in the public sector from 2020. This study evaluated a policy to achieve Net Zero by identifying the trend of changes in building energy performance according to policy and presenting a methodology to analyze the current performance state of energy technology applied to buildings. The final goal was to help stakeholders apply appropriate energy technologies for new buildings. For this study, data collected on building energy efficiency certification over the last four years have shown a gradual increase in energy performance. In addition, K-means cluster analysis was used to analyze the performance status of energy technologies applied to buildings. The high and low clusters of education and office facilities were used to analyze the comparative group (2016-2020, 2020). As a result, the solar module area in both high and low clusters of education facilities increased by 261.1% and 283.5%. In contrast, the solar module area decreased by both high and low clusters of office facilities. The most passive and active technologies showed an increase in energy performance.

• Journal of Korean Library and Information Science Society
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• v.54 no.1
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• pp.25-44
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• 2023

This study was to prepare a development plan for nationwide authority control system based on national authority sharing system of NLK through the survey targeting on libraries which do not participate in the system. Six plans were suggested to establish a nationwide authority control system based on this survey. First, an authority data construction module and a module linked to the national authority sharing system should be developed. Second, describing external identifiers such as ISNI to the national authority sharing system is to provides reliability of data and to utilizes to build linked data. Third, it is necessary to prepare strategies for promoting the national authority sharing system and diversifying services. Fourth, both authority establishment and non-establishment show difficulties and diversity in the selection and description of authorized access point, so it is necessary to prepare rules related to authorized access points. Fifth, since the data described in authority records is not enough, it is necessary to improve and upgrade authority records by using bibliographic records. Sixth, it is necessary to educate librarians about the necessity and function of authority control. As such, this study is meaningful in that it investigated the current status and requirements of libraries that do not participate in the nationwide authority system and sought ways to establish a nationwide cooperative authority control system.

• Journal of the Korean Geotechnical Society
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• v.26 no.3
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• pp.59-68
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• 2010

Systematic risk management is necessary in grand scaled urban construction because of the existence of complicated and various risk factors. Problems of obstructions, adjacent structures, safety, environment, traffic and geotechnical properties need to be solved because urban construction is progressed in limited space not as general earthwork. Therefore the establishment of special risk management system is necessary to manage not only geotechnical properties but also social and cultural uncertainties. This research presents the technique analysis by the current state of risk management technique. Risk factors were noticed and the importance of each factor was estimated through survey. The systemically categorized database was established. Risk extraction module, matrix and score module were developed based on the database. Expected construction budget and time distribution can be computed by Monte Carlo analysis of probabilities and influences. Construction budgets and time distributions of before and after response can be compared and analyzed 80 the risks are manageable for entire whole construction time. This system will be the foundation of standardization and integration. Procurement, efficiency improvement, effective time and resource management are available through integrated management technique development and application. Conclusively decrease in cost and time is expected by systemization of project management.

• KIPS Transactions on Software and Data Engineering
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• v.12 no.10
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• pp.431-436
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• 2023

Recently the incorporation of artificial intelligence approaches in the field of software engineering has been one of the big topics. In the world, there are actively studying in two directions: 1) software engineering for artificial intelligence and 2) artificial intelligence for software engineering. We attempt to apply artificial intelligence to software engineering to identify and refactor bad code module areas. To learn the patterns of bad code elements well, we must have many datasets with bad code elements labeled correctly for artificial intelligence in this task. The current problems have insufficient datasets for learning and can not guarantee the accuracy of the datasets that we collected. To solve this problem, when collecting code data, bad code data is collected only for code module areas with high-complexity, not the entire code. We propose a method for exploring common weakness enumeration by learning the collected dataset based on transfer learning of the CodeBERT model. The CodeBERT model learns the corresponding dataset more about common weakness patterns in code. With this approach, we expect to identify common weakness patterns more accurately better than one in traditional software engineering.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.24 no.4
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• pp.135-140
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• 2024

It is said that PV power generation systems have a long lifespan compared to other renewable energy sources and require little maintenance. However, there are cases where the performance expected during initial design is not achieved due to shading, temperature rise, mismatch, contamination/deterioration of PV modules, failure of inverter, leakage current, and arc generation. Therefore, in order to solve the problems of these systems, the power generation amount and operation status are investigated qualitatively, or the performance is comparatively analyzed based on the performance ratio (PR), which is the performance index of the solar power generation system. However, because it includes large losses, it is difficult to accurately determine whether there are any abnormalities such as performance degradation, failure, or defects in the PV power generation system using only the performance coefficient. In this paper, we studied a status diagnosis algorithm for shading, inverter failure, leakage, and arcing of PV modules to optimize the power generation of PV power generation systems according to changes in the surrounding environment. In addition, using the studied algorithm, we examined the results of an empirical test on condition diagnosis for each area and the resulting optimized operation of power generation.

• Journal of KIISE:Information Networking
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• v.35 no.2
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• pp.99-111
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• 2008

In recent years, the needs for WLANs(Wireless Local Area Networks) technology which can access to Internet anywhere have been dramatically increased particularly in SOHO(Small Office Home Office) and Hot Spot. However, unlike wired networks, there are some unique characteristics of wireless networks. These characteristics include the burst packet losses due to unreliable wireless channel. Note that burst packet losses, which occur when the distance between the wireless station and the AP(Access Point) increase or when obstacles move temporarily between the station and AP, are very frequent in 802.11 networks. Conversely, due to burst packet losses, the performance of 802.11 networks are not always as sufficient as the current application require, particularly when they use TCP at the transport layer. The high packet loss rate over wireless links can trigger unnecessary execution of TCP congestion control algorithm, resulting in performance degradation. In order to overcome the limitations of WLANs environment, MAC-layer LDA(Loss Differentiation Algorithm)has been proposed. MAC-layer LDA prevents TCP's timeout by increasing CRD(Consecutive Retry Duration) higher than burst packet loss duration. However, in the wireless channel with high packet loss rate, MAC-layer LDA does not work well because of two reason: (a) If the CRD is lower than burst packet loss duration due to the limited increase of retry limit, end-to-end performance is degraded. (b) energy of mobile device and bandwidth utilization in the wireless link are wasted unnecessarily by Reducing the drainage speed of the network buffer due to the increase of CRD. In this paper, we propose a new retransmission module based on Cross-layer approach, called BLD(Burst Loss Detection) module, to solve the limitation of previous link layer retransmission schemes. BLD module's algorithm is retransmission mechanism at IEEE 802.11 networks and performs retransmission based on the interaction between retransmission mechanisms of the MAC layer and TCP. From the simulation by using ns-2(Network Simulator), we could see more improved TCP throughput and energy efficiency with the proposed scheme than previous mechanisms.

• Journal of the Korean Solar Energy Society
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• v.32 no.spc3
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• pp.245-254
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• 2012

In photovoltaic system, the characteristics of photovoltaic module such as open circuit voltage and short circuit current will be changed because of cell temperature and solar radiation. Therefore, the boost converter of a PV system connects between the output of photovoltaic system and DC link capacitor of grid connected inverter as controlling duty ratio for maximum power point tracking(MPPT). This paper shows the dynamic characteristics of the boost converter by comparing single-loop and two-loop control algorithm using both analog and digital control. Both proposed compensation methods have been verified with computer simulation to demonstrate the validity of the proposed control schemes.