• Explosives and Blasting
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• v.26 no.2
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• pp.38-44
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• 2008

Recently, planning road construction in South Korea is focused on upgrading of the existing road by rerouting or restructuring. For this, roads under current construction in Korea go for more straight in its alignments and routing. Straight routing makes it all the more required to construct many mountain tunnels and bridges in Korea where mountains are so widely spread. Some portal of mountain tunnel is not rarely planed at high steep slope of mountain valley where it is not easy to secure working space for tunnel excavation. Reverse excavation is an alternative measure for excavation of tunnel portal at high steep slope. Construction in reverse excavation method has three important points requiring careful consideration: 1)planning of pilot tunnel in proper width, height, and length etc., 2)measure against the effect of one-side earth pressure to the direction of tunnel portal, 3)securing tunnel safety against shallow ground condition at portal zone. This paper intends to suggest applicable range of pilot tunnel for reverse excavation at the portal zone located at high steep slope, and shows result of study on the appropriateness of a reverse excavation by means of 3D numerical analysis. Result of 3D numerical analysis for reverse excavation at high steep slope shows that pilot tunneling will be applicable to start from the point $20{\sim}25m$ before the portal from inside the tunnel.

• Journal of the Korean Geotechnical Society
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• v.34 no.7
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• pp.39-49
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• 2018

Jacked pile that involves the use of hydraulic jacks to press the piles into the ground is free from noise and vibration, and is possibly installed within a limited construction area. Thus, as an alternative to conventional pile driving methods, pile jacking could become widely accepted for the construction projects in urban area (e.g., reconstruction or remodeling construction projects). Great concern has arisen over the prediction of axially loaded jacked pile behavior. Against this background, a series of pile load tests were hence conducted on a jacked steel pipe pile installed in weathered zone (i.e., weathered soil and weathered rock). From the test results, base resistance and shaft resistance for each test condition were evaluated and compared with the values predicted by the previous driven pile resistance assessment method. Test results showed that the previous driven pile resistance assessment method highly underestimated both the base and shaft resistances of a jacked pile; differences were more obviously observed with the shaft resistance. The reason for this discrepancy is that a driven pile normally experiences a larger number of loading/unloading cycles during installation, and therefore shows significantly degraded stiffness of surrounding soil. Based on the results of the pile load tests, particular attention was given to the modification of the previous driven pile resistance assessment method for investigating the axially loaded jacked pile behavior.

• Journal of Digital Convergence
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• v.14 no.12
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• pp.405-411
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• 2016

Seoul city is publishing new plans to increase modal share rate of bicycle every year, such as, maintaining bicycle related facilities. But bicycle's modal share rate in Seoul stayed same for the last decade and people are still facing difficulties using bicycle related facilities. These problems are causing bicycle usage as connecting transportation of public transit to decrease. This study looked at the high bicycle modal countries, such as, Netherlands, Germany and Japan to find applicable solutions by analyzing cases and comparing them with cases of highly populated subway station of Sindorim in Seoul. For example, in Germany and Netherlands there is bicycle-parking system to help bikers to access subway easier, in Japan there is underground bicycle parking tower to safely keep high volume of bicycles with in small space. For Seoul city to increase its modal share rate, they should look at problems from users' prospective and solve it by fixing it and improving the services, not by making more facilities.

• Journal of Advanced Navigation Technology
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• v.24 no.4
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• pp.245-250
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• 2020

Currently, unmanned military vehicles under development in Korea have more devices to carry out various missions, and interface cables between them are also increasing. In addition, due to a small space problem inside the unmanned vehicle, devices are required to be miniaturized and integrated. For two reasons, connectors also need to be selected, which makes them vulnerable to noise due to the closer distance between the pins. In this paper, we analyzed how much the magnetic field produced by noise at the connector pin where cable twist is released affects the surrounding pin and presented the guide for optimal pin placement. First, the effect of magnetic field is greater than the crosstalk between pin and pin. Second, the magnetic field on both sides between + and - is strong when approaching one step with noise source. Third, the magnetic field strength is improved when setting the ground pin as the ground pin between the noise and the original signal when approaching the A noise source and the two steps. Fourth, in the case of a differential mode communication, the optimal placement area of the sensitive signal was presented according to positions Tx± and Rx±.

• Journal of the Korean Society of Marine Environment & Safety
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• v.27 no.7
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• pp.1124-1128
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• 2021

As regulations of emissions from ships become more stringent, electric propulsion systems have been increasingly used to solve this problem in vessels ranging from large merchant ships to small and medium-sized ships. Methods for improving the efficiency of the electric propulsion system include the improvement of power sources; the use of a system linked to environmentally friendly power sources, such as batteries, fuel cells, and solar power; and the development of hardware and control methodology for rectifiers, power conversion devices, and propulsion motors. The method using a phase-shifting transformer with diodes has been widely used for rectification. Power semiconductor devices with grid connection to an environmentally friendly power source using DC distribution, a variable speed power source, and the application of small and medium-sized electric propulsion systems have been developed. Accordingly, the demand for active front-end (AFE) rectifiers is increasing. In this study, a method using a neural network rather than a conventional proportional-integral controller was proposed to control the AFE rectifier. Tested controller data were used to design a neural network controller trained through MATLAB/Simulink. The neural network controller was applied to a rectification system designed using PSIM software. The results indicated the effectiveness of improving the waveform and power factor DC output stage according to the load variation. The proposed system can be applied as a rectification system for small and medium-sized environmentally friendly ships.

• Journal of the Korean Geotechnical Society
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• v.39 no.12
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• pp.93-102
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• 2023

Despite recent modifications to building structural standards emphasizing the seismic stability of building foundations, the current design focus remains solely on vertical support, resulting in insufficient consideration of horizontal loads during earthquakes. In this study, we evaluated the dynamic behavior of inclined tripod micropiles (ITMP), which provide additional seismic resistance against horizontal and vertical loads during earthquakes. A comparison of the dynamic characteristics, such as acceleration, displacement, bending moment, and axial force, of ITMP with a 15° installation angle and normal vertical micropiles with a 0° installation angle was performed using dynamic centrifuge model tests. Results show that under moderate seismic loads, the proposed ITMP exhibited lower acceleration responses than the vertical micropiles. However, when subjected to a long-period strong seismic excitation, such as sine (2 Hz), ITMP showed greater responses than the vertical micropiles in terms of acceleration and settlement. These results indicate that the use of ITMP reduces the amplif ication of short-period (high-f requency) contents compared with the use of vertical micropiles. Therefore, ITMP can be used to enhance seismic performance of structures.

• Land and Housing Review
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• v.5 no.1
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• pp.1-10
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• 2014

Health care services in a residential area would accelerate the aging in place. In addition, these changes would play a key role in terms of reducing healthcare costs and leading a healthy lifestyle. The purpose of this study draws the design methodology of community facilities and each dwelling with healthcare services in apartment complex, which the elderly people will enjoy a better health status. This paper presents the result focused on the welfare building in Gayang 7th apartment complex. The intention to receive healthcare services was investigated by occupants. Moreover, design requirements were drawn through in-depth interviews and the state observation to use the service. In the complex, stronger intention to serve the u-Healthcare services was shown to the pre elderly group than the elderly. Both of them had a problem to use and keep the health equipment due to the fact there is not enough space in the unit. Reporting the observation results, the upright-posture furniture attaching the healthcare equipment and the equipment storage should be prepared in the unit. In the public space, the program for these healthcare services can be divided into three parts, i.e. the health status measurement, the healthcare, and the service connected to the surrounding facilities. The health status measurement can be the basic to the health services and its function should be gradually extended. In the complex, the hybrid type with various functions could be applied owing to a new building for welfare; moreover, semi-independent user should be able to receive the home healthcare service.

• Korean Journal of Animal Reproduction
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• v.26 no.2
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• pp.153-163
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• 2002

In vitro matured porcine oocytes have very small volume of perivitellinspace (PVS). In these respect, the effect of sucrose and polybrene on the efficiency of gene transfer was investigated. As a gene (hGH) transfer vehicle, vesicular stomatitis virus glycoprotein pseudotyped retroviral vector (VSV-G) was used. Sucrose treatment has no detrimental effect on the rates of cleavage and resulted in the enlargement of PVS for the efficient introduction of retroviral vector stocks. Introduction rates of retrovirus in 0.5, 1, 2, 3 % sucrose treatment group were higher than that of the non-treatment group (39.3, 43.3, 35.7, 40.7 % vs. 8.3 %), respectively. In addition, we observed that sucrose pretreatment during injection procedure significantly reduce the frequency of polyspermy. In general, polybrene is a polycation essential for retrovirus transduction. The groups with the addition of 0.5, 5, 50$\mu\textrm{g}$/$m\ell$ polybrene exhibited a significant effect on gene transfer compared to that of the non-addition group (56.5, 50.0, 57.1 % vs. 34.6 %), respectively But, when the oocytes were co-injected with retrovirus and 50$\mu\textrm{g}$/$m\ell$ polybrene, the rates of cleavage and blastocyst development were 43.3 and 4.6%, respectively. This rates were lower than those of the non-addition group (70.0 and 17.3 %). In conclusion, sucrose pretreatment have increased efficiency of retroviral mediated gene transfer in porcine oocytes with no damage on in vitro fertilization and embryo development. In addition, sucrose pretreatment was beneficial in polyspermy inhibition. Presence of polybrene during microinjection showed a beneficial effect on the gene transfer in porcine oocytes, in low concentration. And these results will provide an useful tool for production of transgenic pigs by retroviral mediated gene transfer.

• Korean Journal of Heritage: History & Science
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• v.43 no.1
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• pp.190-211
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• 2010

The purpose of this paper is to provide the preliminary data for maintenance of old trees of natural monuments and establishing protection projects. Accordingly, growth conditions, location circumstances, environment and protection management were analyzed for old trees at 34 sites in Gyeongsangbuk-do. Tree forms, crown, trunk and trees' health, leaves volume were analyzed in survey sites. As the results, the growth of Picrasma quassioides in Songsadong, Andong-si and Catalpa ovata in Hongwon-ri, Cheongsong-gun were not in good condition, along with other old trees of 6 cities (Quercus variabilis in Susan-ri, Uljin-gun, Juniperus chinensis in Hujeong-ri, Uljin-gun, Pyrus ussuriensis in Ssangjeon-ri, Uljin-gun, Salix glandulosa var. pilosa in Deokchon-ri, Cheongdo-gun, Pinus densiflora for. multicaulis in Hwasan-ri, Mungyeong-si, Pinus densiflora in Daeha-ri, Mungyeong-si). Accoding to these results, protection project and consistent monitoring are necessary. The analysis results of growth conditions per location circumstances showed that the old trees in the small spaces with large traffic of people were in bad condition. Therefore, it is necessary to secure sufficient space and soil improvement for such trees. The analysis results of growth conditions per species showed that Zelkova serrata, Quercus spp., Pinus densiflora are in good condition while Salix koreensis and others, i.e. a singular tree, are in poor condition. Thus, relatively smaller individuals and separately situated trees need careful management in their protection. The analysis results of trunk's growth ratio showed that Pinus densiflora, Ginkgo biloba, Zelkova serrata are in good condition whereas Juniperus chinensis, Quercus variabilis, Salix koreensis are not. It is a recent trend that tree surgeries are gradually decreasing; there are a number of damaged trees with no maintenance/management, and several sites requiring mend trunks management and cabling, bracing in protection and management projects. Hence, in the future, local government and management organizations should plan for systematic management and establish a protection plan for the natural monument trees. Also, 12 sites were found to be in need to purchase lands in order to secure the growth spaces, and since most of these areas are available for purchase, it is needed to promote a budget and purchase those areas through persuasion of the owner. These areas seems crucial in order to maximize the effect of conservation efforts and budgets for the preservation and restoration of the old trees.

• Journal of the Korean Institute of Landscape Architecture
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• v.40 no.4
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• pp.51-61
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• 2012

Kyong-Eui Railway used to be one of the major cross-country railways connecting Busan and Shineuiju. Being the central axis of logistics and transportation in Korea, it also signifies a symbolic meaning of the people's desire for the unification of divided Korean peninsula. A steam locomotive that had stopped in Jangdan Station was bombed out during the Korean War. The locomotive has been neglected and covered with rust in DMZ over a half century, and now is becoming a historic reminder of divided Korea. The initial design approach was based on the three main perspectives of the relocation plan of the steam locomotive in Jangdan Station which is designated as the registered cultural asset no. 78: historical significance, role of a monumental space, and influence on and from the local culture and tourism. Three design subjects were especially highlighted which would represent the identity of the cultural asset, the stream locomotive. First, a vertical watching deck was installed to provide various view points toward the locomotive while ensuring the security of visitors as well as the cultural asset. Second, the Dokgae bride area has good design potentials being on the railway. However, the site is too narrow. Thus, a new ramp and a stairway were placed responding to the existing topography so that the pedestrian environment could be secured last, to respect the local context where the locomotive was originally located, mulberry trees in the locomotive were transplanted as well. Flowering plants were planted around the display area for better ventilation to minimize the negative impact on the locomotive.