• Korean Journal of Materials Research
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• v.29 no.4
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• pp.205-210
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• 2019

$Pb(Zr,Ti)O_3$ (PZT) is used for the various piezoelectric devices owing to its high piezoelectric properties. However, lead (Pb), which is contained in PZT, causes various environment contaminations. $(K,Na)NbO_3$ (NKN) is the most well-known candidate for a lead-free composition to replace PZT. A single crystal has excellent piezoelectric-properties and its properties can be changed by changing the orientation direction. It is hard to fabricate a NKN single crystal due to the sodium and potassium. Thus, $(Na,K)NbO_3-Ba(Cu,Nb)O_3$ (NKN-BCuN) is chosen to fabricate the single crystal with relative ease. NKN-BCuN pellets consist of two parts, yellow single crystals and gray poly-crystals that contain copper. The area that has a large amount of copper particles may melt at low temperature but not the other areas. The liquid phase may be responsible for the abnormal grain growth in NKN-BCuN ceramics. The dielectric constant and tan ${\delta}$ are measured to be 684 and 0.036 at 1 kHz in NKN-BCuN, respectively. The coercive field and remnant polarization are 14 kV/cm and $20{\mu}C/cm^2$.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.12
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• pp.265-271
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• 2018

This paper presents a method for detecting damage to a structure at low cost using its impedance. The impedance technique is a typical method to detect local damage for structural health monitoring. This is a common technique for estimating damage by monitoring the electro-mechanical admittance signal of the structure. To apply this technique, an expensive impedance analyzer is generally used. On the other hand, it is necessary to develop a low-cost variant to effectively disseminate the technique. In this study, a method based on the transfer impedance using a function generator and digital multimeter, which are generally used in the laboratory instead of an impedance analyzer, was developed. That is, this technique estimates the damage by comparing the damage index using the amplitude ratio of the output voltage measured in the healthy and damaged state. A transfer impedance test was carried out on a steel specimen. By comparing the damage index, the presence of damage could be assessed reasonably. This study is a basic investigation of an impedance-based low-cost damage detection method that can be used effectively for structural health monitoring if supplemented with future research to estimate the damage location and severity.

• Korean Journal of Breeding Science
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• v.50 no.4
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• pp.497-503
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• 2018

A strawberry variety 'Arihyang' was derived as an artificial cross between 'Tochiotome' and 'Seolhyang' in 2014. The seedling and line selections were conducted from 2014 to 2015. Preliminary and advanced yield trials of '14-5-5,' which was the final selected line, were conducted from 2015 to 2017. 'Arihyang' is suitable for forced cultivation and has strong plant vigor, uniformly large-sized fruit, and a high yield compared to those of the check variety, 'Seolhyang' and 'Maehyang.' Especially, vitamin C was at a significant level, which was approximately 15% higher than that of 'Seolhyang.' The average number of flowers per first flower cluster was 10.5, which could reduce the labor of thinning fruit. Its fruit has a conical shape, dark red color, and glossy skin. The fruit was of good quality but has recommendations for harvest at the fully ripened stage. 'Arihyang' has intermediate resistant to phytophthora crown rot, but is susceptible to powdery mildew, gray mold, anthracnose, and fusarium wilt. It is reguired to manage major diseases and pests using optimum cultivation techniques and chemical control.

• The Journal of the Korea institute of electronic communication sciences
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• v.16 no.4
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• pp.577-584
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• 2021

Electrical energy is an essential component in present societies, which is an important basis for our technological society. In the design of new power infrastructure, it is important to consider the psychological aspects of how our culture considers and aspects its development as an integral component of the community environment. The construction of new high voltage overhead transmission lines has become a controversial issue for public policy of government due to social opposition. The members of community are concerned about how these power lines may have an impact on their lives, basically caused by their effects on health and safety. The landscape and visual impact is one of the most impact that can be easily perceived for local community. The computer 3D simulation of new landscape is illustrated by a real life use corresponding to the selection of the power line route with least observability for local community. This paper used ArcGIS(geographic information system tool) for planning, survey, basic route and detailed route, route for implementation of transmission line corridor. Also, the paper showed the map of natural environment, living environment, safety and altitude using database of power line corridor, and transmission siting model was developed by this study. The suggested landscape of computer simulation with lowest visibility on a power line zone can contribute to reducing oppositions of local community and accelerating the construction of new power lines.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.31 no.4
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• pp.166-173
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• 2021

The rutile phase of TiO₂ forms a stable phase at high temperatures compared to anatase phase, but the stable temperature range of anatase changes depending on the synthesis conditions. In this study, nano-sized TiO₂ was synthesized by the Sol-gel method using TiOSO₄ and a mixed solvent of ethanol and distilled water, and the phase change of anatase and rutile according to pH and heat treatment temperature was investigated. Changes in the ratio of anatase and rutile were observed by changing the pH (3, 5, 7, 9) and heat treatment temperature (500, 600, 700, 800, 900℃) conditions of the prepared TiO₂. As a result of observing these changes through XRD and FE-SEM analysis, anatase TiO₂ at 500℃ and rutile TiO₂ at 900℃ were observed. According to the pH, at these intermediate temperatures of 600, 700 and 800℃, the ratio of anatase and rutile changes. At 700℃, it was concluded that pH = 3~5 had a larger ratio of anatase TiO₂, and pH = 7~9 had a larger ratio of rutile TiO₂.

• Journal of the Korean Institute of Traditional Landscape Architecture
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• v.39 no.3
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• pp.1-14
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• 2021

This study attempted to examine the loving pigeon culture practiced in traditional gardens and to illuminate the aspect of pigeons as a landscape animal material. In order to understand the culture of enjoying old garden through pigeons, the contents were analyzed for the translated version of the old literatures and paintings. Pigeons have been used as Jeonseo-gu(傳書鳩) and also for medicinal purposes and food. Pigeons have various symbolic meanings such as abundance, hospitality, and longevity. From the Goryeo Dynasty to the early Joseon Dynasty, pigeons were raised in the palace and private garden. In the late Joseon Dynasty, temporary trend of ornamental pigeon culture occurred. Pigeons were synesthesia materials that enriched the forest. Various beautiful pigeons created a variable landscape of the primeval forest as a moving landscape material. The bell sounds that appear differently depending on the pigeon's movement led to a rich auditory experience of the landscape. The pigeon house was an ornamental element that enriched the old garden along with the pigeon. The owners of garden were involved in gardening through the act of buying a pigeon house and placing it in the garden or making a pigeon house themselves. In addition, the writers planted plum trees, peach trees, apricot trees, and hawthorn trees as a symbol of spring and a source of food for pigeons, and expressed them in poems and paintings. This study has a limitation in that the translation of the old text was used as an analysis data. The follow-up studies on specific cases of raising pigeons in the old garden, in modern and contemporary landscape spaces are urged.

• Journal of The Korean Society of Integrative Medicine
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• v.9 no.4
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• pp.283-289
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• 2021

Purpose : The purpose of this study is to investigate the effect of mid frequency electrical stimulation during squat exercise on the muscle activity and muscle activity ratio of vastus medialis oblique and vastus lateralis, and to prepare scientific basic data for exercise intervention using mid frequency electrical stimulation. Methods : This study was conducted with students from University C located in Busan, and among a total of 123 subjects, 12 subjects who complained of knee joint dysfunction between 80 and 90 points using the Kujala patellofemoral score (KPS) were used. All subjects participated in the experiment for 3 days, and MVIC values were measured for normalization of muscle activity values on the first day. For the two days, participants participated in the experiment and performed squat exercise or squat exercise receiving mid-frequency electrical stimulation in random order. Measurements were taken in the squat position immediately after the squat exercise, and muscle activities of vastus medialis oblique and vastus lateralis were measured. The measured data were compared through the dependent t test, and the statistical significance level was set to .05. Results : According to the results of this study, in the case of applying mid-frequency electrical stimulation together in the ratio of vastus medialis oblique and vastus lateralis muscle activity during squat exercise, higher values were observed compared to the case of not applying mid-frequency electrical stimulation together, and statistically significant. Also, when mid-frequency electrical stimulation was applied to both vastus medialis oblique and vastus lateralis activities during the squat exercise, higher values were shown compared to the case where the mid-frequency electrical stimulation was not applied together, but there was no statistically significant difference. Conclusion : The results of this study reported that mid-frequency electrical stimulation provided to vastus medialis oblique increased the muscle activity ratio of vastus medialis oblique and vastus lateralis. Therefore, the improvement of coordination due to the enhancement of the activity of vastus medialis oblique through mid-frequency electrical stimulation will be more helpful in the treatment of patellofemoral pain syndrome patient. In addition, it is hoped that the electrical stimulation method applied to exercise will be widely used.

• Korean Journal of Materials Research
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• v.29 no.11
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• pp.720-726
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• 2019

Recently, research on cost reduction and efficiency improvement of crystalline silicon(c-Si) photovoltaic(PV) module has been conducted. In order to reduce costs, the thickness of solar cell wafers is becoming thinner. If the thickness of the wafer is reduced, cracking of wafer may occur in high temperature processes during the c-Si PV module manufacturing process. To solve this problem, a low temperature process has been proposed. Conductive paste(CP) is used for low temperature processing; it contains Sn57.6Bi0.4Ag component and can be electrically combined with solar cells and ribbons at a melting point of $150^{\circ}C$. Use of CP in the PV module manufacturing process can minimize cracks of solar cells. When CP is applied to solar cells, the output varies with the amount of CP, and so the optimum amount of CP must be found. In this paper, in order to find the optimal CP application amount, we manufactured several c-Si PV modules with different CP amounts. The amount control of CP is fixed at air pressure (500 kPa) and nozzle diameter 22G(outer diameter 0.72Ø, inner 0.42Ø) of dispenser; only speed is controlled. The c-Si PV module output is measured to analyze the difference according to the amount of CP and analyzed by optical microscope and Alpha-step. As the result, the optimum amount of CP is 0.452 ~ 0.544 g on solar cells.

• Korean Journal of Poultry Science
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• v.47 no.4
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• pp.275-283
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• 2020

This experiment was conducted to investigate the effect of the addition of enzymes and microorganisms to broiler feed on productivity, carcass characteristics, intestinal microflora, and feces odor. A total of one-hundred eighty 180 chicks (Ross 308) were randomly assigned to 5 treatments with 3 replications each having 12 birds per pen. The experimental group was divided into 0.1% EZ group (0.1% metallo-protease added to the feed), 0.2% EZ group (0.2% metallo-protease added to the feed), M group (2.0% Bacillus veleznesis CE 100 added to the feed), and MW group (2.0% Bacillus veleznesis CE 100 added to the feed and drinking water). In the results, final body weight, body weight gain, the feed conversion ratio, protein efficiency, and energy efficiency were not significantly different among all treatments in across all periods. Carcass weight, proventriculus, gizzard, heart, small intestine, cecum, and rectum weight were not significantly different among all of the treatments. However the liver weight was significantly higher in the 0.1% EZ group than in the control, M and MW groups (P< 0.05). E. coli was significantly lower in MW than in the control and M (P<0.05), and it was significantly higher in the M than 0.2% EZ and MW (P<0.05). H2S emissions in feces was not significantly different among all treatments, but NH3 emissions was were significantly higher in 0.1% EZ than in MW (P<0.05). In conclusion, the addition of 0.1% of metallo-protease was effective in the development of the liver of broilers.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.22 no.6
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• pp.591-598
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• 2021

One of the requirements of metro trains is to stop with precision to ensure that the train can stop precisely at the designated location on the platform. If this is not satisfied, interference with the screen door occurs, causing inconvenience to passengers and delays in operation. In the case of an automatic operated train, the current position is determined by the current speed information of the train, and control is performed by issuing an acceleration/deceleration command. Therefore, accurate control becomes impossible if the error of the speed information is large. In metro railroads, a Precision Stop Marker (PSM) is used to correct the position error, so that the error of stop control can be reduced by correcting the position error at a specific point. On the other hand, because the PSM itself has only position information, it does not compensate for the speed error. This paper proposes a method for performing in-place stop control by estimating the speed with the PSM progress information. The speed can be estimated when the train is operated at a constant deceleration speed, and the target deceleration can be obtained to perform stop control. The feasibility and excellence of the proposed method are shown through a numerical simulation.