• 방사성폐기물학회지
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• 제8권1호
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• pp.85-89
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• 2010

사용후핵연료 파이로프로세싱 공정 생성물인 우라늄 전착물을 잉곳 형태로 주조하는 공정이 있다. 이 논문에서는 실험실 규모의 우라늄 전착물 잉곳 주조 장치에 대한 설계 개념을 소개하고, 이에 따라 제작된 장치의 성능 시험 결과 및 우라늄을 사용한 잉곳 주조 시험 결과를 소개한다. 이 장치는 도가니를 경동시켜 우라늄 용탕을 주형에 주입하여 우라늄 잉곳을 제조하며, 우라늄 전착물을 연속으로 주입할 수 있는 컵 형태의 원료 장입장치를 장착하였다. 이러한 장치를 사용하면 우라늄 전착물의 잉곳 생산성을 높일 수 있다. 실험 결과 우라늄 원료를 장입하여 주조한 결과 수축공이 적은 양호한 주물을 제조하는데 성공하였으며, 이러한 실험실 규모의 장치를 개발한 경험을 활용하여 공학규모의 장치를 설계하는데 활용하였다.

• 전자공학회논문지C
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• 제35C권9호
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• pp.81-92
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• 1998

실수형 최적화 문제의 전역 최적해를 빠르고 정확하게 찾을 가능성을 높이기 위해, 서로 다른 진화특성을 가지는 여러 부집단들을 사용한 새로운 하이브리드 기법이 제안된다. 제안된 알고리듬은 세 개의 부집단을 사용하는데, 복잡한 적합도 함수를 가지는 문제에서 좋은 성능을 보이는 NPOSA 알고리듬이 두개의 부집단에 적용되고, 진화 방향과 크기가 조절되는 자기 적응 진화 알고리듬이 나머지 하나의 부집단에 적용되었다. 각 부집단들은 서로 다른 방법으로 진화하며 부집단들간의 상호교류를 통해 전역 최적해로 빠르게 도달하게 한다. 이 기법의 효율성은 몇 개의 표준 테스트 문제들을 사용하여 검증하였다. 마지막으로, 제안한 알고리듬이 실제 문제에 적용 가능함을 보이기 위해 카메라 파라메터의 최적값을 찾는 문제에 적용하였다. 보정 블럭에서 측정된 특징점들을 사용하여 오차 함수를 정의한 후, 하이브리드 방법이 그 오차 함수를 최소화하는 카메라 파라메터의 값을 찾을 수 있음을 보였다.

• 한국기계가공학회지
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• 제16권6호
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• pp.1-6
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• 2017

Recently, the brittle materials such as ceramics, glass, sapphire and textile material have been widely used in semiconductors, aerospace and automobile owing to high functional characteristics. On the other hand, it has the characteristics of difficult-to-cut material relative to all materials. In this study, diamond electro-deposited band-saw machine was developed to operate stably using water-coolant type through relative motion between band-saw tool and $Al_2O_3$ material. High densified $Al_2O_3$ material was manufactured by spark plasma sintering method. The bulk density was observed by the Archimedes law and the theoretical density was estimated to be $3.88g/cm^3$ and its hardness 14.7 MPa. From the dicing sawing test of $Al_2O_3$ specimen, behavior of surface roughness and band-saw wear are dominantly affected by the increase of the band-saw linear velocity. Additionally, an continuous pattern type of diamond band-saw was a very effective due to entry impact as a one-off for brittle material.

• 대한설비공학회:학술대회논문집
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• 대한설비공학회 2008년도 동계학술발표대회 논문집
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• pp.80-83
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• 2008

As SOC (Social Overhead Capital) has been expanded, the highway road construction has been accelerated and city road system has been more complicated. So, long road tunnels have been increased and traffic flow rate also has been raised. Accordingly, the exhausting gas of vehicle cars seriously deteriorates the tunnel inside air quality and driving view. In order to improve tunnel inside air quality, we may need to introduce a compulsory ventilation system as well as natural ventilation mechanism. The natural ventilation mechanism is enough for short tunnels, meanwhile longer tunnels require a specific compulsory ventilation facility. Many foreign countries already have been devoting on development of effective tunnel ventilation system and especially, some European nations and Japan have already applied their developed tunnel ventilation system for longer road tunnels. More recently, as the quality of life improved, our concerns about safety of driving and better driving environment have been increased. In order to obtain clearer and longer driving view, we are more interested in EP tunnel ventilation system in order to remove floating contaminants and automobile exhaust gas. Evan though it's been a long time since many European countries and Japan applied more economical and environment-friendly tunnel ventilation system with their self-developed Electrostatic Precipitator, we are still dependant on imported system from foreign nations. Therefore, we need to develop our unique technical know-how for optimum design tools through validity investigation and continuous possibility examination, eventually in order to localize the tunnel ventilation system technology. In this project, we will manufacture test-run products to examine the performance of system in order to develop main parts of tunnel ventilation system such as electrostatic precipitator, high voltage power generator, water treatment system, etc.

• 설비공학논문집
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• 제16권11호
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• pp.1051-1059
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• 2004

Two phase thermosyphone loop for electronics cooling are designed and manufactured to test its performance under the partial load and low environment temperature conditions. The thermosyphone device has six evaporators connected parallel for the purpose of cooling six power amplifier units (PAU) independently. The heater modules for simulating PAUs are adhered with thermal pad to the evaporator plates to reduce the contact resistance. There are unbalanced distributions of liquid refrigerant in the differently heated evaporators due to the vapor pressure difference. To reduce the vapor pressure differences caused by partial heating, two evaporators are connected each other using the copper tube. The pressure regulation tube successfully reduces these unbalances and it is good candidates for a field distributed systems. Under the low environment temperature operating condition, such as $-30^{\circ}C$, there may be unexpected subcooling in condenser. It leads the very low saturation pressure, and under this condition there exists explosive boiling in evaporator. The abrupt pressure rise due to the explosive boiling inhibits the supplement of liquid refrigerant to the evaporator for continuous cooling. Finally the cooling cycle will be broken. For the normal circulation of refrigerant there may be an optimum cooling air flow rate in condenser to adjust the given heat load.

• 한국지반환경공학회 논문집
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• 제14권10호
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• pp.5-9
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• 2013

점토성-사질토에 분포하는 양이온 금속들과 석유를 효율적으로 회수하기 위한 방법으로 동전기법 연구를 제안하였다. 제안된 동전기법은 투수계수가 낮은 매질 속에 존재하는 중금속에 포함되어 있는 양이온 금속 또는 석유등의 회수를 위해, 양극탱크(Anode chamber)에서 발생하는 잉여가스의 압력을 이용해서 점토성-사질토 샘플에 재주입하여 회수하는 기법이다. 제안된 동전기법의 성능을 확인하기 위해 제작된 샘플은 총 7일간에 점진적으로 압력을 증가시켜 최종 30psi($2.11kgf/cm^2$)의 압력으로 압축과정을 거쳐 완성되었다. 압축 전 샘플 내에 구리링을 삽입하여, 실험 종료 후 구리링의 변화된 모습을 관찰하였다. 본 연구에서 사용된 모듈은 가압식 모듈과 비가압식 모듈이고, 각각의 실험 테스트는 24시간 동안 2V/cm의 전압 경사 조건으로 연속적인 처리 공정으로 진행하였다. 그 결과, 가압식 모듈의 효율이 비가입식 모듈보다 우수한 것으로 나타났다.

• 임상간호연구
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• 제25권3호
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• pp.237-250
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• 2019

Purpose: The aim of this study was to investigate the satisfaction of newly graduated nurses with educational programs and their experiences in role transition. Methods: Data were collected from November 1 to December 15, 2018 and 483 new graduate nurses working at 15 tertiary hospitals and 10 general hospitals participated. For data collection, self-report questionnaires including the Casey-Fink Graduate Nurse Experience Survey tool and satisfaction with education were used. Data were analyzed using descriptive statistics, t-test, and one-way analysis of variance. Results: Satisfaction with education ranged from 3.09 to 3.27, and satisfaction with preceptors was 3.45(maximum 4). The skill that new nurses ranked as most difficult during the first 3 months was charting/documentation, and throughout a whole year, the top 4 difficult skills were cardiopulmonary resuscitation/emergency response, ventilator care, end-of-life care, and prioritization/time management. In comfort/confidence, new graduates felt most comfortable with support and least comfortable with patient safety. More than 50 percent of new graduates experienced stress during role transition, and the most frequently experienced stressors were related to job performance and personal life. Levels of satisfaction with education and comfort/confidence differed according to the hospital type and number of preceptors for new nurses. Conclusion: In order to facilitate the transition of new graduate nurses to professional nurse, an extended period of education, systematic and standardized transition programs, and continuous support during the first year of practice are required.

• Steel and Composite Structures
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• 제23권4호
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• pp.453-464
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• 2017

The square tubed-reinforced concrete (TRC) column is a kind of special concrete-filled steel tube (CFST) columns, in which the outer thin-walled steel tube does not pass through the beam-column joint, so that the longitudinal steel reinforcing bars in the RC beam are continuous through the connection zone. However, there is a possible decrease of the axial bearing capacity at the TRC column to RC beam connection due to the discontinuity of the column tube, which is a concern to engineers. 24 connections and 7 square TRC columns were tested under axial compression. The primary parameters considered in the tests are: (1) connection location (corner, exterior and interior); (2) dimensions of RC beam cross section; (3) RC beam type (with or without horizontal haunches); (4) tube type (with or without stiffening ribs). The test results show that all specimens have relatively high load-carrying capacity and satisfactory ductility. With a proper design, the connections exhibit higher axial resistance and better ductility performance than the TRC column. The feasibility of this type of connections is verified.

• 대한원격탐사학회지
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• 제15권3호
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• pp.209-216
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• 1999

독자기술에 의한 소형위성 개발이라는 목표아래 지난 4년 반에 걸쳐서 개발된 우리별 3호가 성공적으로 발사되었다. 초기운용 기간동안 위성의 각 서브시스템에 대한 시험이 있었으며 모든 서브시스템에 대한 시험이 있었으며 모든 서브시스템이 설계된 바와 같이 정상적으로 동작함을 검증할 수 있었다. 이 기간동안 우리별 3호에 탑재된 카메라가 수십회 지구를 촬영하여 그 데이터를 지상으로 송신하고 수신된 영상데이터를 분석하여 카메라 및 송수신 시스템의 성능을 분석할 수 있었다. 본 논문에서는 우리별 3호의 다대역 지구관측 센서 영상의 촬영, 데이터 송신, 수신 및 저장시스템을 소개하고 위성 초기운용 시 시험했던 영상데이터 송수신 시스템의 성능을 기술한다. 수신시스템은 개발 시 주어졌던 1% 미만의 전송에러를 만족하였으며 앞으로 지속적인 시스템 시험 및 안정화를 통해서 이러한 수신시스템의 에러율은 최소화 될 것이다.

• Membrane and Water Treatment
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• 제10권4호
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• pp.287-298
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• 2019

Lotus leaf has a special dual micro and nano surface structure which gives its highly hydrophobic surface characteristics and so-called self cleaning effect. In order to endow PVDF hollow fiber membrane with this special structure and improve the hydrophobicity of membrane surface, PVDF hollow fiber composite membranes was obtained through the immersion coating of poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) dilute solution on the outside surface of PVDF support membrane. The prepared PVDF composite membranes were used in the vacuum membrane distillation (VMD) for the desalination. The effects of PVDF-HFP dilute solution concentration in the dope solution and coating time on VMD separation performance was studied. Membranes were characterized by SEM, WCA measurement, porosity, and liquid entry pressure of water. VMD test was carried out using $35g{\cdot}L^{-1}$ NaCl aqueous solution as the feed solution at feed temperature of $30^{\circ}C$ and the permeate pressure of 31.3 kPa. The vapour flux reached a maximum when PVDF-HFP concentration in the dilute solution was 5 wt% and the coating time was kept in the range of 10-60 s. This was attributed to the well configuration of micro-nano rods which was similar with the dual micro-nano structure on the lotus leaf. Compared with the original PVDF membrane, the salt rejection can be well maintained which was greater than 99.99 % meanwhile permeation water conductivity was kept at a low value of $7-9{\mu}S{\cdot}cm^{-1}$ during the continuous testing for 360 h.