• Journal of the Korean Society for Railway
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• v.12 no.3
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• pp.405-411
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• 2009

Railway signaling system in a rapid transit using the ATC system the approved a speed limit to a train and a part of signaling system in a metro approved a distance which is possible to move. Referring to the way of transmitting train control information, there are the one transmitting it to the on-board system of a train using the direct track, the another transmitting it establishing an instrument, and the other transmitting an instrument by a railway track. The one is the method using the direct track as a conductor for composing the part of the track and attaining the information controlling a train by transmitting a signal to the track. It is used for the high-speed railway and the subway. The method using the track attains information by transmitting it to returned information, and the on-board system of a train attains it by magnetic coupling. Because many reinforcing bars on the concrete slab track are used, interaction between a rail and a reinforcing bar that is not produced on ballast track is made. Due to the interaction, the electric characteristic of rail is changed. In the current paper, we numerically computed the coupling coefficient between the rail and the reinforcing bar based on the concrete slab track throughout the model related to the rail and the reinforcing bar using the concrete slab track that is used in the second interval of the Gyeongbu high-speed railway, and we defined the coupling coefficient not changed in the electric characteristic of rail in the condition that there is no interaction between the rail and the reinforcing bar.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.06a
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• pp.294-294
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• 2008

동시 증발 증착법 화합물의 구성원자를 독립적으로 증발시켜서 기판에 증착하는 방법이다. 각 물질은 온도에 따른 증기압을 가지는데 각 물질의 온도를 조절하여 증착률을 조절한다. 보트에서 떠난 원자가 기판에 도달할 확률은 챔버의 진공도, 보토와 기판과의 거리 등에 의하여 영향을 받는다. 진공도가 나쁠수록, 보트와 기판과의 거리가 멀수록 기판에 도달할 확률이 떨어진다. 동시증발 증착법을 이용한 SmBCO 초전도층 증착에서 각 물질의 기판에 도달하는 원자비를 조절하기 위하여 QCM(증착률 측정장치), QCM 가이드를 사용하였다. QCM sensor 입구에 튜브형태의 QCM 가이드를 설치하고 QCM 가이드가 특정한 물질의 증발보트를 향하도록 배치하였다. 따라서 각 보트에서 떠난 원자들은 특정한 QCM sensor에 도달하게 되고 결국 3원소(Sm, Ba, Cu)의 증착률의 비를 조절함으로써 조성비를 조절할 수 있게 된다. QCM 증착률의 비와 실제 조성비는 여러 가지 변수에 의하여 영향을 받는 다. 대표적인 변수는 챔버의 진공도, QCM 가이드의 직경 및 길이, QCM 센서와 보트와의 거리 등이 있다. 진공도가 높을수록 특정 보트에서 떠난 원자들이 QCM 가이드 입구에 도달할 확률이 낮아지고, QCM 가이드의 직경이 좁을수록 가이드 내벽에 흡착될 확률이 높아진다. 또한 QCM센서와 보트와의 거리가 멀수록 챔버내 잔류가스의 원자들과 충돌확률이 높아지므로 도달확률이 줄어들게 된다. 동시 증발 증확법에서 조성비의 재현성을 높이기 위해서는 매회 증착실험에서 진공도가 일정해야 하며, QCM 가이드와 보트와의 거리를 되도록 최소화 하고, QCM 직경을 크게 하는 것이 유리하다.

• KEPCO Journal on Electric Power and Energy
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• v.5 no.3
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• pp.141-147
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• 2019

Recently, the biggest issue in the electricity industry is the increase in renewable energy, and various technologies are being developed to ensure the capacity of the power system. In addition, super-grids linking power systems are being pushed to utilize eco-friendly energy between countries and regions worldwide. The HVDC transmission technology is required to link the power network between regions with different characteristics of the power system such as frequency and voltage. Until now, Korea has applied HVDC transmission technology that connects mainland and Jeju Island with submarine cables. But, the HVDC transmission technology is still developing for long-distance high-capacity power transmission from power parks on the east coast to load-tight areas near the metropolitan area. Considering the high population density and mountainous domestic environment, it is pushing for commercialization of the design technology of the ${\pm}500kV$ Double Bipole with metallic return wire transmission line to transmit large-scale power of 8 GW using minimal right of ways. In this paper, the insulation characteristics were studied for the design of double-bipole transmission tower with metallic return wire, which is the first time in the world. And the air insulation characteristics resistant to the various overvoltage phenomena occurring on transmission lines were verified through a full-scale impulse voltage test.

• Journal of the Korean Institute of Gas
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• v.27 no.2
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• pp.79-85
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• 2023

Recently, in the semiconductor process, large companies are seeking process changes from memory semiconductors to the foundry due to the increase in demand due to the 4th industry. industry is expanding. The characteristics of special gases and precursors, which are raw materials used to produce these semiconductor chips, are toxic, pyrophoric, inflammable, and corrosive. These semiconductor raw materials are operated in a closed system and do not leak to the outside during normal times, but when leaked, they spread to the inside of the gas box, and when proper ventilation is not provided inside the gas box, they spread to the outside, causing fires, explosions, or toxic substances. It can lead to major accidents such as leakage. Recently, there have been cases of accidents in which hazardous materials leaked from the closed system of the semi conductor process and spread to the inside and outside of the gas box. . In this study, we propose preventive measures based on the case of an accident in which raw material leaked from the VCR fitting, which is the connection part of the semiconductor raw material transfer pipe, and spread to the outside of the gas box.

• Korean Chemical Engineering Research
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• v.61 no.3
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• pp.426-438
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• 2023

Lithium-sulfur batteries, recently attracting attention as next-generation batteries, have high energy density but are limited in application due to sulfur's insulating properties, shuttle phenomenon, and volume expansion. This study used an economical and simple vacuum filtration method to prepare a freestanding electrode without a binder and collector. Carbon nanotubes (CNTs) are used to improve the electrical conductivity of sulfur, where CNT also acts as both collector and conductor. In addition, metal oxides (MO_x, M=Ni, Mg), which are easy to adsorb lithium polysulfide, are added to the CNT/S electrode to suppress the shuttle reaction in lithium-sulfur batteries, which is a result of suppressing the loss of active sulfur material due to the excellent adsorption of lithium polysulfide by metal oxides. The MO_x@CNT/S electrode exhibited higher capacity characteristics and cycle stability than the CNT/S electrode without metal oxides. Among the MO_x@CNT/S electrodes, the NiO@CNT/S electrode displayed a high discharge capacity of 780 mAh g^-1 at 1 C and an extreme capacity decrease to 134 mAh g^-1 after 200 cycles. Although the MgO@CNT/S electrode exhibited a low discharge rate of 544 mAh g^-1 in the initial cycle, it showed good cycle stability with 90% of capacity retention up to 200 cycles. Further, to achieve high capacity and cycle stability, the Ni_0.7Mg_0.3O@CNT/S electrode, mixed with Ni:Mg in the ratio of 0.7:0.3, manifested an initial discharge rate of 755 mAh g^-1 (1 C) and a capacity retention rate of more than 90% after 200 cycles. Therefore, applying binary metal oxides to CNT/S provides a freestanding electrode for developing economical and high-performance Li-S batteries, effectively improving lithium polysulfide's high capacity characteristics and dissolution.

• Journal of Korean Academy of Nursing
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• v.11 no.2
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• pp.55-68
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• 1981

The prime object of the study is to evaluate how much all the students of the Nursing Schools throughout the nation are in comprehension toward the application of nursing process to clinical experience as means of systematic solution of nursing problems. An effort has been made to find out the actual state whether they are in practice of clinical experience in accordance with application of nursing process, over the period of four weeks managing from December 1st to 28th, 1980 and centering on 36 nursing schools, and meanwhile and evaluation, employing the assessment tool used by Bertuccietal, has been made on the nursing process notes recorded by 200 senions out of 21 nursing schools where application of nursing process to clinical experience being in practice. The assessment tool is composed of 5 different criteria in view of patient nursing and authors made an attempt to find out the result of clinical experience on application students in accordance with 5 different scoring criteria and further evaluating all the findings thereof. The findings were disposed of accordance with practice duration and criteria of the specific sudents subject to this finding as to verify the scoring difference in significance and of which the results are as follows: 1) as of now, in 21 (58.2%) out of 36 nursing Schools nursing process in being appliced in clinical experience. 2) Schools that started the application of nursing process to clinical experience amount to - for more than 4 yrs -6 (28.6％) - for 2 to 3 yrs-11s(52.4％) - for 1 yr -4 (19.0％) 3) As for the response upon application of nursing process. To clinical etperience, the largest voice (61.9%) heard was that it is rather difficult beyond the lecturing thereof, to practically apply it outs patients and the second voice (19.1%) turned out to be that it is hard to put in practice owing to uninformed nurses of the process serving in the clinical field. 4) The response. Of the processors assigned to instruction as to the most difficult problem in criteria of nursing process, the largest voice (38.2%) centered on the problem assessment while the second voice (17.7%) on the indirect nursing activity and the objective data respectively and considered to be the easiest was the indirect nursing activity (11.7%). 5) In order for a satisfactory. application of nursing process to clinical experience hence-forth, it has been pointed out that sufficient number of nurses should be supplemented in clinical field (44.1%) and at the same time supplementory education (35.3%) centered around professors be necessary. 6) Of the criteria that record result of nursing process, a significant difference in comprehension of subjective and objective data has been revealed according to the degree of the practice duration of application to clinical experience. For instance, while although poor it may seen, only 74.9% in subjective data and 71.1% in objective data represent the student group in practice for more than 4 years and only 56.3% in subjective data and 66.8% in objective data represent the student group in practice for 2 to 3 years but they still surpass in comprehension over the student group in practice for 1 year attaning only 19.6% in subjective data and 16.8% in objective data (P < 0.005). 7) As for problem assessment, the student group who started application of nursing process for 4 years stand for 37,7% the group for 2 to 3 years started for 25.3% and the group for 1 year started for 5.4%, revealing no significant difference according to duration (P < 0.5) and as poor as to indicate only 22.8% on an overage is in comprehension. 8) On direct and indirect nursing activity, the student group of for more than 4 years in appling nursing process (representing 49.5% in direct nursing activity, 21.4% in indirect nursing activity). Know more about it than the student group of for 2 to 3 years (representing 36.3% in direct nursing activity, 20.8% in indirect nursing activity) but revealed no significant difference. (P ＜ 0.5) 9) The student group applying nursing process for more than 4 years subjective data (74.9%) comprehend were more than objective data (71.1%) but shown no significant difference (P < 0.5). 10) However, the student group applying nursing process for 2 to 3 years comprehend objective data (66.8%) well ever subjective data (55.5%) indicating that 40.9% in average is in comprehension, thereby revealing a significant difference (P < 0.005). 11) On the other hand, the student group applying nursing process to clinical experience for 1 year had revealed themselves as poorly as to comprehend only 11.7% are an average of it, revealing no significant difference (P < 0.5). In consequence of the fore going, I the conductor of the present study, hereby suggest the following points: 1) Application of nursing process to clinical experience be practiced in all the Nursing Schools all over the nation at the earliest possible date in order that scientific nursing be prevailed (as of now only 58.0%), 2) In teaching nursing process, it is desirable to teach specific method of applying to practical clinical situations. 3) In order to meet the end of satisfactory application of nursing process to clinical experience, sufgecient nursing man power be sysplemented in clinical field and at the save time supplementary education by professors is necessary. 4) Sinces the students whose application duration of nursing process to clinical experience is longer comprehend more about it, it is reguired that the schools not yet in practice of the application be promptlyurged to follow. 5) Of the criteria recording nursing process, since it is comparatively hard to comprehend“assessment”and“Direct and indirect nursing activity”, a concentrated instruction is desirable. 6) The students whose duration of application of nursing process to clinical experience falls short of 1 years be put in a concentrated guidance program on individual criterion.

• Journal of Korean Society of Environmental Engineers
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• v.29 no.6
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• pp.715-721
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• 2007

Residual calcium concentration is high, in general, at the effluent of the fluoride removal process in the electronics industry manufacturing semiconductor and LCD. To increase the stability of the membrane process incorporated for reuse of wastewater, the residual calcium is required to be pre-removed. Hyperkinetic Vortex Crystallization(HVC) process was installed in the electronics industry manufecturing semi conductor as a pilot scale for accelerating calcification of calcium ion. Compared to the conventional soda ash method, the 31% higher calcium removal efficiency was achieved when HVC was applied at the same sodium carbonate dosage. In order to maintain the economic calcium removal target of 70% preset by manufacturer, the dosing concentration of the soda ash was 530 mg/L based on influent flowrate. The seed concentration in the reactor was one of the critical factors and should be maintained in the range of $800\sim1,200mg$ SS/L to maximize the calcium removal efficiency. The calcite production rate was 0.30 g SS/g $Na_2CO_3$ in the average. The economic HVC passing time of the mixture was in the range of $2\sim5$ times. Relatively, stable calcium concentration was maintained in the range of $30\sim72$ mg/L(average 49 mg/L) although the calcium concentration in the feed was severely fluctuated with $74\sim359$ mg/L(average 173 mg/L). The HVC process was characterized as environment-friendly technology reducing chemical dosage and chemical sludge production and minimizing maintenance cost.

• The Journal of Engineering Geology
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• v.16 no.1 s.47
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• pp.69-83
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• 2006

This study aims to evaluate a complex groundwater flow system around the underground oil storage caverns using the concept of hydraulic compartment. For the hydrogeological analysis, the hydraulic testing data, the evolution of groundwater levels in 28 surface monitoring boreholes and pressure variation of 95 horizontal and 63 vertical water curtain holes in the caverns were utilized. At the cavern level, the Hydraulic Conductor Domains(fracture zones) are characterized one local major fracture zone(NE-1)and two local fracture zones between the FZ-1 and FZ-2 fracture zones. The Hydraulic Rock Domain(rock mass) is divided into four compartments by the above local fracture zones. Two Hydraulic Rock Domains(A, B) around the FZ-2 zone have a relatively high initial groundwater pressures up to $15kg/cm^2$ and the differences between the upper and lower groundwater levels, measured from the monitoring holes equipped with double completion, are in the range of 10 and 40 m throughout the construction stage, indicating relatively good hydraulic connection between the near surface and bedrock groundwater systems. On the other hand, two Hydraulic Rock Domains(C, D) adjacent to the FZ-1, the groundwater levels in the upper and lower zones are shown a great difference in the maximum of 120 m and the high water levels in the upper groundwater system were not varied during the construction stage. This might be resulted from the very low hydraulic conductivity$(7.2X10^{-10}m/sec)$ in the zone, six times lower than that of Domain C, D. Groundwater recharge rates obtained from the numerical modeling are 2% of the annual mean precipitation(1,356mm/year) for 20 years.