• Korean Chemical Engineering Research
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• v.51 no.6
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• pp.692-699
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• 2013

In this study, isothermal (350, 375, 400, 425, 450, 500, $850^{\circ}C$) experiments were carried out using a custom-made thermobalance to analyze the thermal decomposition properties of refuse plastic fuel (RPF), which is to be used as a cofiring fuel with a sub-bituminous coal at commercial circulating fluidized bed (CFB) boiler in Korea. In isothermal pyrolysis results, no change in the reaction model was observed in the temperature range of $375{\sim}450^{\circ}C$ and it was revealed that the first order chemical reaction (F1) is the most suitable among 12 reaction models. The activation energy shows similar results irrespective of application of reaction model in that the activation energy was 39.44 kcal/mol and 36.96 kcal/mol when using Arrhenius equation and iso-conversional method ($0.5{\leq}X{\leq}0.9$) respectively. Mean-while, the devolatilization time ($t_{dev}$) according to particle size (d) of RPF could be expressed as $t_{dev}=10.38d^{2.88}$ at $850^{\circ}C$, operation temperature of CFB and for even distribution and oxidation of RPF in CFB boiler, we found that the relationship of average dispersion distance (x) and particle size was $x{\leq}1.58d^{1.44}$.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.29 no.7A
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• pp.814-827
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• 2004

The compressed mode is used to perform inter-frequency and inter-system handover in WCDMA. The instantaneous transmit power is increased in the compressed frame in order to keep the QoS(Quality of Service) unaffected by the reduced processing gain. Furthermore, since the inner loop power control is not active during the transmission gap and the effect of interleaving is decreased, a higher Eb/No target is required, which directly affects the system performance. Due to the impact on performance, the compressed mode should be activated by the RNC(Radio Network Controller) only when there is real need to execute an inter-frequency or inter-system handover. However, 3GPP does not define the method that decides the compressed mode activation. In order to reduce performance degradation, there is need the decision method. In this paper, we consider a combined cell structure in which some neighbor cells have a frequency the same as serving cell and the others have a different frequency or system. Under consideration, we analyze the effect of the compressed mode on the WCDMA forward link performance. In order to avoid performance degradation, we propose an UE(User Equipment) measurement method that can restrict the activation area of the compressed mode of UE that does not need it and evaluate its performance by simulations. Analytical results show that the use of the compressed mode affects the performance degradation. And simulation results show that proposed method leads to better performance.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.12
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• pp.629-635
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• 2019

In this study, we analyzed the effect of FAN and oil cooler application on APU. MIL-STD-810 was applied to the atmospheric environment and radiation dose in order to perform thermal flow analysis. The heat flow was analyzed for the case in which the inlet / outlet fan was applied (Case 1), the case in which the inlet fan and the oil cooler were applied (Case 2), and the case in which the inlet / outlet fan and the oil cooler were applied (Case 3). As a result, it was confirmed that the cylinder head temperature of Case 3 was 21.4 times lower than that of Case 1 and 8.0 times lower than that of Case 2. Experiments were conducted under the same ambient conditions in order to examine the validity of the results. The numerical values and experimental results showed a difference of less than 7%. Through this, we were able to confirm that the APU heat flow optimization model satisfies the design conditions. The results of this study are expected to be used as basic data for optimizing heat flow of APU.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.9
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• pp.397-404
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• 2020

The military tactical vehicle currently being operated is manufactured by improving the parts of commercial vehicles. In addition, the power supply system is applied by installing a separate converter inside the communication room to secure the operating environment of communication equipment. On the other hand, due to electromagnetic radiation noise, there are problems in frequent noise and deterioration in communication sensitivity during wireless communication in vehicles. To improve these, an advanced power supply system is applied, which is also equipped with an alternator to receive power required for communication equipment reducing broadband electromagnetic radiation noise. An additionally installed alternator, which is located in the engine room, is separated from the communication room where communication equipment is operated and is expected to reduce the effect of electromagnetic radiation noise generated from the power supply system. To verify these, a broadband radiation test was performed on a previous and advanced one. As a result, the broadband radiation noise of vehicles with an applied advanced power supply system satisfied all of the domestic vehicle safety standards and reduced in most of the sections except for some frequencies compared to previous typed vehicles. In particular, broadband radiation noise was decreased by up to 10.751 dB𝜇V/m in the vertical sections in 170 to 200 MHz on the right side of the vehicle.

• Proceedings of the Korean Society for Agricultural Machinery Conference
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• 2002.07a
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• pp.195-201
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• 2002

입고ㆍ예냉ㆍ출고까지 전 공정을 자동화하고 진공압력을 작물의 품온에 따라 능동적으로 제어할 수 있고 진공챔버내에 콜드트랩을 설치하여 냉각효율을 향상시킨 진공예냉장치를 개발하여 고랭지 배추와 느타리버섯, 상추를 대상으로 예냉성능을 평가하고 예냉이 이들 작물에 미치는 영향을 분석하였다. 가. 새로 개발된 진공식 예냉장치는 공급컨베이어, 좌우 자동 슬라이딩 문, 이송컨베이어, 진공챔버, 진공펌프 콜드트랩, 냉동기로 구성되어 있다. 팔레트를 공급컨베이어에 올려놓고 작동을 시작하면, 입구문이 열리고 팔레트가 진공챔버내로 이송되면, 진공펌프에 의해 진공챔버내의 압력을 떨어뜨리고, 콜드트랩과 냉동기가 작동되어 예냉이 시작된다. 예냉이 완료되면 출구문이 열리고 이송컨베이어가 역회전하여 밖으로 배출되도록 되어있다. 나. 제작된 예냉장치의 예냉성능을 평가하기 위하여 느타리버섯, 고랭지 배추, 상추를 대상으로 냉각속도, 냉각균일도, 예냉후 저장중 품질변화시험을 실시하였다. 다. 시험결과 냉각소요시간은 느타리버섯의 경우 초기품온 15.2$^{\circ}C$에서 $1.5^{\circ}C$까지 냉각시키는데 24분, 고랭지배추는 13.5$^{\circ}C$에서 3.7$^{\circ}C$까지 냉각시키는데 18분, 상추는 13.4$^{\circ}C$에서 2.$0^{\circ}C$까지 냉각시키는데 24분 소요되었다. 평균냉각속도는 느타리버섯이 34.3$^{\circ}C$/h, 고랭지배추 32.6$^{\circ}C$/h, 상추 28.5$^{\circ}C$/h로 나타났다. 라. 또한 각층간의 냉각균일도를 알아보기 위하여 포장상자내에서 표면 품온과 내부품온변화를 조사한 결과 차이가 거의 없어 균일한 냉각이 가능하였다.생기 양단의 온도차는 높게 나타났고, 재생기 양단의 압력 차는 낮게 나타났다. 재생기 축열재로서 철망-철선을 사용할 경우 철선-철망 ø1.2-150이 전열 표면적은 작으나 재생기 양단의 온도차가 가장 큰 것으로 나타났으며 재생기 양단의 압력 차는 가장 낮게 나타나 공시 철망- 철선 혼합 축열재중 가장 우수함을 알 수 있다. 4. 철망사이에 철선을 삽입한 축열재의 경우, 철망사이에 삽입한 철선의 직경이 큰 것이 철선의 직경이 작은 것보다 재생기의 양단의 온도차가 높게 나타났고 재생기 양단의 압력차는 작게 나타났다. 그러므로 철망사이에 철선을 삽입한 것 중 성능이 우수한 것은 150-ø2. 0-150으로 나타났다. 5. 실험한 재생기 축열재들 중에서 성능이 우수한 것들을 비교한 결과, 복합 철선 ø1.2-1 50이 가장 성능이 좋은 것으로 나타났다.적외선.열풍 복합건조방법이 높게 나타나 이것은 곡물 표면에 원적외선 방사에의한 복사열이 전달되어 열장해를 받았기 때문으로 판단되며, 금후 더 연구하여 적정 열풍온도 및 방사체 크기를 구명해야 할 것이다.으로 보여진다 따라서 옻나무 유래 F는 포유동물의 생식기능에 중요하게 작용하는 것으로 사료된다.된다.정량 분석한 결과이다. 시편의 조성은 33.6 at% U, 66.4 at% O의 결과를 얻었다. 산화물 핵연료의 표면 관찰 및 정량 분석 시험시 시편 표면을 전도성 물질로 증착시키지 않고, Silver Paint 에 시편을 접착하는 방법으로도 만족한 시험 결과를 얻을 수 있었다.째, 회복기 중에 일어나는 입자들의 유입은 자기폭풍의 지속시간을 연장시키는 경향을 보이며 큰 자기폭풍일수록 현저했다. 주상에서 관측된 이러한 특성은 서브스톰 확장기 활동이 자기폭풍의 발달과 밀접한 관계가 있음을 시사한다.se that were all low in two aspects, named "the Nonsignificant group". And th

• Proceedings of the Korean Society for Rock Mechanics Conference
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• 2008.03a
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• pp.51-68
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• 2008

When the train enters into a tunnel a high speed, pressure waves are generated inside the tunnel. The pressure waves at propagate in a form of compression wave toward the tunnel exit and a fraction of the compression waves that arrives at the exit of the tunnel are discharged to outside of the tunnel and the remainder is reflected into the tunnel as expansion waves. The compression waves emitted from the tunnel does not radiate in a specific direction but in all directions. If the amplitude of the compression wave is great, it causes noise and vibration, and it is called "Micro-Pressure Wave." "Micro-Pressure Wave" must be considered as a decision for the optimum tunnel cross-section as the amplitude of the compression wave depends on train speed, tunnel length, area of tunnel and train. Therefore, this paper introduces the case study of Micro-Pressure Wave characteristics for determination of tunnel cross section in Honam high speed railway, the pressure inside the tunnel and the micro-pressure waves at tunnel exit were measured at Hwashin 5 tunnel in Kyungbu HSR line. At the same time. a test of train operation model was performed and then the measurement results and test results were compared to verify that the various parameters used as input conditions for the numerical simulations, which were appropriate. Also a model test was performed, in order to analysis of the Micro-Pressure Wave Mitigation Performance by Type of Hood at Entrance Portal.

• Proceedings of the KWS Conference
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• 2009.11a
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• pp.12-12
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• 2009

터빈에서 핵심부품인 로터는 블레이드를 원심 운동시키는 대형 단조강이며, 고압의 증기 조건에서 고속회전하며 고온에서 운전과 저온에서 과속시험 동안 높은 원심력을 받는다. 또한 기동/정지 천이 동안 열응력을 받기 때문에, 이러한 운전조건에 부합되는 소재로서는 높은 Creep 강도 및 피로강도를 가지는 CrMoV type의 강종이 사용되어져 왔다. 발전소의 대용량화 및 고온화에 따라 종래의 증기조건에서 사용되어져 왔던 1%CrMoV강은 내산화성 및 내부식성이 문제가 되어 더 이상 사용이 불가하며, 고온/고압하에서도 우수한 소재 특성을 가지는 12%Cr강의 사용이 필수적이다. 그러나 12%Cr강으로 제작되는 로타는 Cr 양이 높기 때문에 저널부에 Galling 또는 Scuffing 이라 불리는 부적절한 마모현상과 사용 중 소착이 발생하기 쉬운 단점이 있기 때문에, 저널부에 Cr 함유량 2~3% 이하의 저합금강을 오버레이 용접하여 육성하는 일체형 가공구조의 로타 저널부가 주목되어 왔다. 따라서 본 연구에서는 Large scale 로타가 용접 도중 급열 및 급냉이 되지 않으면서 균일한 온도로 일정 시간 유지할 수 있는 열관리 장치 개발, 최적 오버레이 용접조건 선정 및 용접부 건전성 시험 평가를 통하여 12%Cr 로타 저널부의 최적 오버레이 용접공정을 확립하고자 하였다. 용접 열관리 장치는 전기저항 가열방식을 적용하고 있으며 용접이 최종 완료되기 전까지 로타 제품 전체는 $93^{\circ}C$이상의 온도로 유지 되어져야 하며, 규정 용접후열처리 온도는 $650^{\circ}C{\pm}14^{\circ}C$ 이다. 또한 로타 오버레이 용접은 모재 Set up $\Rightarrow$ 용접예열 $\Rightarrow$ GTA용접 $\Rightarrow$ SA용접 $\Rightarrow$ 용접후열(Post heating) $\Rightarrow$ 용접후열처리(PWHT) $\Rightarrow$ 정삭가공 $\Rightarrow$ NDE(UT) 순으로 수행 되어진다 실제 로타의 1/3 Scale로 시험편을 제작하여, 오버레이 mockup 시험을 수행한 후 화학성분, 경도 분포, 인장강도, 충격인성 및 굽힘시험을 수행한 결과, 오버레이 용접에서 요구되어지는 용접 물성값을 만족하는 것으로 확인되었다. 또한 균열 등의 선형 결함이나 기공, 슬라그 혼입과 같은 결함은 관찰되지 않았으며, 용접 시 아크의 안정성과 슬라그의 박리성은 양호하였으며 비드의 외관도 미려하여 용접 작업성도 양호하였다.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.2 no.1
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• pp.60-67
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• 2004

The exposure dose form recycling of a large amount of the steel scrap from the KRR-1＆2 decommissioning activities was evaluated, and also the clearance level(draft) was derived. The maximum individual dose and collective dose were evaluated by modifying internal dose conversion factor which was based on the concept of effective dose in ICRP 60, applied to the RESRAD-RECYCLE ver 3.06 computing code, IAEA Safety Series 111-P-1.1 and NUREG-1640 as the assessment tool. The result of assessment for individual dose and collective dose is 23.9 $\mu$Sv per year and 0.11 man$.$Sv per year respectively. The clearance levels were ultimately determined by extracting the most conservative value form the results of the generic assessment and specific assessment methodologies. The result of clearance level for radionuclides( $Co^{60}$ , C $s^{l37}$) is less than 1.14${\times}$10$^{-1}$ Bq/g to comply with the clearance criterion(maximum individual dose : 10 $\mu$Sv per year, collective dose : 1 man$.$Sv per year) provided for Korea Atomic Energy Act and relevant regulations.s.

• Korean Security Journal
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• no.32
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• pp.123-150
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• 2012

The purpose of this study was to seek practical intelligences for certain persons who wish to be a guard by studying for what practical public guards' recognition of organization and vocation is. The results of this study were as follows. First, Six study participants presented 'Respect within members', 'Atmosphere like family', 'Premium members', and 'Economic compensation & wealth of budget' as essential requirements for the best guard organization. Second, they also presented 'Systematic daily task & training', 'Exact selection system', and 'Strong cohesion & teamwork' as strong points of their organization. Third, they mentioned 'Internal evaluation system', 'Lack of education contents', and 'Limited position circulation' as weak points of their organization. Fourth, they mentioned that they feel encouraged itself as they work in the best guard organization, while they were skeptical when the citizens did not cooperate with them and they were not fully rewarded for their injury. Fifth, they expressed 'Difficulty of business cooperation', 'Unstable living patterns', 'Inconsistent assessment', and 'Continuing tension' as difficulties for performing the duties and stress causes. Lastly, they recognized of job security and self-esteem as they work in the best guard organization as advantages of a job, while they recognized of controlled life, low salaries and welfare level compared to duty importance and risks as disadvantages of a job. Consequently, students who wish to be a guard should consider job and organization attributes and set their career goals refer to these results.

• Proceedings of the Korean Radioactive Waste Society Conference
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• 2003.11a
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• pp.660-664
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• 2003

The exposure dose form recycling on a large amount of the steel scrap from the KRR-1&2 decommissioning activities was evaluated, and also the clearance level was derived. The maximum individual dose and collective dose were evaluated by modifying internal dose conversion factor which was based on the concept of effective dose in ICRP 60, applied to the RESRAD-RECYCLE ver 3.06 computing code, IAEA Safety Series III-P-1.1 and NUREG-1640 as the assessment tool. The result of assessment for individual dose and collective dose is 23.9 ${\mu}Sv$ per year and 0.11 man$\cdot$Sv per year respectively. The clearance levels were ultimately determined by extracting the most conservative value form the results of the generic assessment and specific assessment methodologies. The result of clearance level for radionuclides($Co^60$, $Cs^137$) is less than $1.67{\times}10^{-1}$ Bq/g to comply with the clearance criterion(maximum individual dose : 10 $\muSv$ per year, collective dose : 1 man$\cdot$Sv per year) provided for Korea Atomic Energy Act and relevant regulations.