• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.7
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• pp.704-712
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• 2016

Recently, the installation of photovoltaic (PV) systems has been increasing due to the worldwide interest in eco-friendly and infinitely abundant solar energy. However, the output power of PV systems is highly influenced by the surrounding environment. For instance, a string of PV systems composed of modules in series may become inoperable under cloudy conditions or when in the shade of a building. In other words, under these conditions, the existing control method of PV systems does not allow the string to be operated in the normal way, because its output voltage is lower than the operating range of the grid connected inverter. In order to overcome this problem, we propose a new control method using a DC-DC voltage regulator which can compensate for the voltage of each string in the PV system. Also, based on the PSIM S/W, we model the DC-DC voltage regulator with constant voltage control & MPPT (Maximum Power Point Tracking) control functions and 3-Phase grid connected inverter with PLL (Phase-Locked Loop) control function. From the simulation results, it is confirmed that the present control method can improve the operating efficiency of PV systems by compensating for the fluctuation of the voltage of the strings caused by the surrounding conditions.

• Korean Journal of Plant Resources
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• v.33 no.5
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• pp.436-445
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• 2020

Goji berry (Lycium chinense Mill.) is one of medicinal plants. Its leaves has been used to manufacture the functional foods by replacing the dried-fruit because of low production costs. In order to produce the leaves of uniform quality, continuous selection and the establishment of cultivation techniques were required. Among the eleven recommended cultivars, 'Myeongan' showed high yielding and rapid regeneration after cutting. The dried-leaf yield was linearly increased from 106 kg/10a on May 16 to 287 kg/10a on June 20. An appropriate cutting date and cutting length (about 60-70 cm) was important factors for its efficient regeneration. The late cutting times were not suitable due to difficulties during plant harvesting because of stem rigidity and thorn generation. The betaine content of leaves ranged from 1.43 ~ 2.63% and significantly affected by the varieties and the cutting dates. The main physiological functionality of leaf was Angiotesin-1-converting enzyme (ACE) inhibitory activity, representing the anti-hypertensive. The other physiological functionalities, XOD inhibitory activity, antioxidant activity, tyrosinase inhibitory activity, SOD-like activity, α-glucosidase inhibitory activity and fibrinolytic activity, were not detected or less than 20%.

• Korean Journal of Weed Science
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• v.4 no.2
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• pp.211-218
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• 1984

In order to establish the chemical weed control systems in orchard, field experiments were conducted to evaluate the effects of spray methods and mixing of herbicides. The mixtured dosage of glyphosate 100cc/10a and 2,4-D 75㏄/10a showed higher control effects than mono-treatment of glyphosate and paraquat on Artemisia vulgaris var. indica and Polygonum hydropiper L. And oxyfluorfen was more effective in reducing the cover rate and dry weight of weeds than simazine and alachlor on 75th day after treatment. In the mixing experiment of land and foliar appling herbicides. The effect of glyphosate on May 17 followed by oxyfluorfen on June 12 showed the best control effect.

• The Journal of Engineering Geology
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• v.22 no.2
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• pp.233-241
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• 2012

The objectives of this study were to test geothermal conductivity (k), water velocity, water quantity, and pipe pressure from a ground heat exchanger in the field, and then to analyze these data in relation to the effectiveness and economical efficiency for application of geothermal energy. After installation of the apparatus required for field tests, geothermal conductivity values were obtained from three different cases (second, third, and fourth). The k values of the second case (506 m depth) and third case (151 m depth) are approximately 2.9 and 2.8, respectively. The k value of the fourth case (506 m depth, double pipe) is 2.5, which is similar to the second and third cases. This result indicates that hole depth is a critical factor for geothermal applications. Analysis of the field data (k, water velocity, water quantity, and pipe pressure) reveals that a single geothermal system at 506 m depth is more economically efficient than three geothermal systems at depths intervals of 151 m. Although it is more expensive to install a geothermal system at 506 m depth than at 151 m depth, test results showed that the geothermal system of the fourth case (506 m, double pipe) is more economically efficient than the system at 151 m depth. Considering the optional cost of maintenance, which is a non-operational expense, the geothermal system of the fourth case is economically efficient. Large cities and areas with high land prices should make greater use of geothermal energy.

• Journal of Energy Engineering
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• v.27 no.4
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• pp.1-12
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• 2018

The code and standards related to fuel cells were analyzed to derive the SOFC(Solid Oxide Fuel Cell) stack safety performance evaluation items and evaluation methode. Safety performance evluation of the SOFC stack was tested by quoting derived test items. The stack used in the test is an anode-supported type 2 Cell stack (Active surface area : 220cm) manufactured by MICO Inc, and SOFC stack safety performance evaluation system used for the test is self-manufactured. We conducted a leakage test, current voltage characteristic test, rated output test, and power response characteristics test. In the safety performance evaluation test, the stack showed no gas leakage, the maximum output and rated output was recorded to 65.6 W(1.41 V, 46.5 A, $422mA/cm^2$), 62.3 W(1.57 V, 40 A, $363mA/cm^2$). In the power response characteristics test verified that the output is kept stable within two seconds. At the maximum load (40 A) and the minimum load (8 A), the output was recorded 62 W and 16W in $750^{\circ}C$. This study will contribute to the universalization and to provide much safe environment of operating the solid oxide fuel cell system.

• Journal of Convergence for Information Technology
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• v.8 no.6
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• pp.367-374
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• 2018

The purpose of this research is to promote traditional markets, which are part of urban regeneration project, and to promote cultural and tourism market by applying characteristics and differentiated elements through story development through market-related resources in order to secure identity of the JeCheon Central market that lost function of the traditional market and regional aging of the traditional market. To this end, the basic survey and analysis of the Jecheon area and the current situation of the Jecheon Central Market were conducted to diagnose problems and to analyze keywords through surveys by local merchants and visitors. By drawing up measures to vitalize the Jecheon Central Market by floor and space, the Jecheon Central Market's design story is developed and applied so that it can restore the image of the local traditional market through regional and cultural elements and become a center of space and culture that can become a landmark for the region in the future. The storytelling designed for this purpose shall be linked to the spatial planning of each floor as well as the C.I. and exterior of the C.I. and the building of the Jecheon Central Market, and the identity of the Jecheon Central Market can be reestablishe.

• Journal of the Society of Disaster Information
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• v.15 no.1
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• pp.109-120
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• 2019

Purpose: This study is the analysis of the relationship between the physical safety of the urban spaces and the aging in place tendency of the elderly. Method: For analysis, the physical safety of the urban space is divided into four elements: outdoor space and building safety, pedestrian safety, transportation safety and living safety, and for aging in place, the 5-point Likert scale was used. A questionnaire survey was conducted for 411 elderly people aged 65 or older living in Seoul for each of the five urban community in Seoul. Results: 78.6% of the respondents answered that they are good at continuing to live in the present living area, the elderly living in Seoul has the high tendency of aging in place. The ratio of respondents who answered that good at living continuedly is in the order of southeast, northwest, southwest, northeast, and downtown. Conclusion: When the percentage of respondents who answered that they are good at staying in the current living area is high, not only the overall physical safety but also the average of the physical safety factors of the urban space are also high, physical safety of urban spaces is a factor affecting aging in place. Based on the results of the study, it can be applied as a method to create a safe city in the process of city development or urban renewal in the future.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.35 no.5
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• pp.277-286
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• 2022

The elastic and inelastic responses obtained from the experimental and analytical results of two RC building structures under the service level earthquake (SLE) and maximum considered earthquake (MCE) in Korea were used to weinvestigate the characteristics of the mechanisms resisting shear and torsional behavior in torsionally unbalanced structures. Equations representing the interactive effect of translational drift and torsional deformation on the shear force and torsional moment were proposed. Because there is no correlation in the behavior between elastic and inelastic forces and strains, the incremental shear forces and incremental torsional moments were analyzed in terms of their corresponding incremental drifts and incremental torsional deformations with respect to the yield, unloading, and reloading phases around the maximum edge-frame drift. In the elastic combination of the two dominant modes, the translational drift mainly contributes to the shear force, whereas the torsional deformation contributes significantly to the overall torsional moment. However, this phenomenon is mostly altered in the inelastic response such that the incremental translational drift contributes to both the incremental shear forces and incremental torsional moments. In addition, the given equation is used to account for all phenomena, such as the reduction in torsional eccentricity, degradation of torsional stiffness, and apparent energy generation in an inelastic response.

• Korean Journal of Construction Engineering and Management
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• v.24 no.5
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• pp.12-21
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• 2023

Green remodeling proposed in the Korean New Deal is a project to build or remodel eco-friendly and energy-efficient buildings using renewable energy facilities and high-performance insulation for public buildings. The government intends to achieve the carbon emission reduction target by conducting green remodeling. Major overseas cities that conduct green remodeling are actively promoting technology support and promotion along with energy performance evaluation according to building characteristics, subsidies for private revitalization, and tax benefits. With this background, the analysis of the current status and problems of the green remodeling project was performed and the Activation factors of Green Remodeling were derived from survey results. This study suggested strategic measures such as a participation of civil society, promotion, and priority selection of administration and policy measures such as a leading role of the public sector, expanding support for the socially underprivileged, and financial support and tax benefits. And this study results are expected to be utilized as basic data to promote the green remodeling project.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2021.10a
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• pp.582-583
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• 2021

As the production of new and renewable energy such as solar and wind power has diversified, microgrid systems that can simultaneously produce and consume have been introduced. . In general, a decrease in electricity prices through solar power is expected in summer, so producer protection is required. In this paper, we propose a transparent and safe gift power transaction system between users using blockchain in a microgrid environment. A futures is simply a contract in which the buyer is obligated to buy electricity or the seller is obliged to sell electricity at a fixed price and a predetermined futures price. This system proposes a futures trading algorithm that searches for futures prices and concludes power transactions with automated operations without user intervention by using a smart contract, a reliable executable code within the blockchain network. If a power producer thinks that the price during the peak production period (Hajj) is likely to decrease during production planning, it sells futures first in the futures market and buys back futures during the peak production period (Haj) to make a profit in the spot market. losses can be compensated. In addition, if there is a risk that the price of electricity will rise when a sales contract is concluded, a broker can compensate for a loss in the spot market by first buying futures in the futures market and liquidating futures when the sales contract is fulfilled.