• 한국공작기계학회논문집
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• 제15권1호
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• pp.76-81
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• 2006

Modem after-treatment technology has been developed variously in order to decrease exhausted emission in diesel engine. However, it seems very difficult to comply with updated stringent emission standards. Specially, it has been many years that exhaust gas from gasoline automobile rather than from diesel is the major object concerned by Korea and other countries, and it is strongly required on the reduction techniques on harmful NOx and PM among those compositions. Thus, this research focused on the electronic control EGR and the target for this research is heavy-duty turbo-diesel engine with EGR technology(High pressure route and low pressure route system).

• 한국재료학회지
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• 제18권3호
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• pp.123-127
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• 2008

The production of tin oxide ($SnO_2$) microrods on iridium (Ir)-coated substrates was achieved through the thermal evaporation of Sn powders in which a sufficiently high $O_2$ partial pressure was employed. Scanning electron microscopy revealed that the product consisted of microrods with diameters that ranged from 0.9 to $40\;{\mu}m$. X-ray diffraction, high-resolution transmission electron microscopy, and selected area electron diffraction indicated that the microrods were $SnO_2$ with a rutile structure. As the microrod tips were free of metal particles, it was determined that the growth of $SnO_2$ microrods via the present route was dominated by a vapor-solid mechanism. The thickening of rod-like structures was related to the utilization of sufficiently high $O_2$ partial pressure during the synthesis process, whereas low $O_2$ partial pressure facilitated the production of thin rods.

• 한국산학기술학회논문지
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• 제11권11호
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• pp.4137-4144
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• 2010

본 논문에서는 승용디젤엔진에서 유해배출물을 저감시키는 동시에 고연비를 달성하기 위하여 2단 터보과급기와 EGR 장치를 장착한 디젤엔진에 대하여 EGR 배열 방식이 EGR율에 미치는 영향을 분석하기 위하여 시뮬레이션을 수행하였다. 이를 위하여 AMESim을 사용하였고 엔진 부품을 위하여 IFP Engine Library를 사용하였다. 고압, 저압, 반저압의 3가지 배열 방식이 고려되었다. 일반적으로 많이 사용되는 고압 방식과 저압 방식의 EGR 배열이 공연비 21에서 각각 6.4%, 10.0%의 EGR율을 보인 반면, 두 방식의 혼합형인 반저압 EGR 배열 방식의 EGR율은 18.0%의 값을 보였다. 따라서 2단 터보과급기와 EGR 장치를 장착한 엔진 설계시 엔진 성능과 유해배출물 발생량의 관점에서 반저압 방식 EGR 시스템이 적절함을 보였다.

• 한국산업융합학회 논문집
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• 제21권1호
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• pp.29-36
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• 2018

Low pressure casting process for unidirectional carbon fiber reinforced aluminum (UD-CF/Al) composites which is an infiltration route of molten Al into porous UD-CF preform has been a cost-effective way to obtain metal matrix composites (MMCs) but, easy to cause non-uniform fiber distribution as CF clustering. Such clustered CFs have been a problem to decrease the density and thermal conductivity (TC) of composites, due to the existence of pores in the clustered area. To obtain high thermal performance composites for heat-sink application, the relationship between fiber distribution and porosity has to be clearly investigated. In this study, the CF distribution was evaluated with quantification approach by using two-dimensional spatial distribution method as local number 2-dimension (LN2D) analysis. Note that the CFs distribution in composites sensitively changed by sizes of Cu bridging particles between the CFs added in the UD-CF preform fabrication stage, and influenced on only $LN2D_{var}$ values.

• 한국운동역학회지
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• 제21권1호
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• pp.67-75
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• 2011

The purpose of this study was to find the difference in gait patterns when elderly and young people walk by analyzing COP, Gait Line, Foot pressure pattern, and ensuring the original biomechanics technology of developing high performance footwear for the elderly. The subjects who took part in the test consist of 20 elderly people and 20 young people. The physical features of the elderly people that were recruited for the study are as below: 20 healthy male subjects(elderly people) with an average age of 75.43 yrs(S.D 6.46 yrs), weight of 68.10 kg(S.D 0.94 kg) and a height of 168.65 cm(S.D 1.47 cm). Foot pressure pattern data was collected using a EMED-AT system(Novel Gmbh, Germany) operating at the 50 Hz during walking. The results are as follow : COP route of the elderly leans to lateral compared to the young, and Gait Line from heel to toe is not clear and laterally curved. At the same time, a contact are aonthe midfoot is high compared to the young, and maximum force of the forefoot is low. As a result of analysis, in order to develop high performance footwear for the elderly, it is necessary to develop lasts and soles reflecting the elderly's gait patterns.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제10권7호
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• pp.3100-3116
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• 2016

With the rapid development of urban traffic system and fast increasing of vehicle numbers, the traditional centralized ways to generate the source-destination shortest path in terms of travel time(the optimal path) encounter several problems, such as high server pressure, low query efficiency, roads state without in-time updating. With the widespread use of smart cameras in the urban traffic and surveillance system, this paper maps the optimal path finding problem in the dynamic road network to the shortest routing problem in the smart camera networks. The proposed distributed optimal path generation algorithm employs the delay routing and caching mechanism. Real-time route update is also presented to adapt to the dynamic road network. The test result shows that this algorithm has advantages in both query time and query packet numbers.

• 해양환경안전학회:학술대회논문집
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• 해양환경안전학회 2008년도 춘계학술발표회
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• pp.185-189
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• 2008

동계 한반도의 기후에 큰 영향을 미치는 한랭 건조한 대륙성고기압이 서해를 거쳐 한반도의 확장해 올 때 서해 연안지역의 적설량과 서해의 해황이 어떻게 상호 영향을 미치는가를 알아보았다. 서해 연안지역의 적설량은 인천은 1월, 2월과 12월, 군산과 목포는 1월, 12월과 2월 순으로 적설량이 많다. 한랭 건조한 대륙기단의 중심이 서해를 통과하는 경우가, 서해를 통과하지 않는 경우보다 인천지역에서는 약 3.4배, 군산에서는 약 2.3배 정도를 해양으로부터 많은 열을 흡수한다. 또한, 서해 연안지역에서 1일 10 cm 이상의 대설이 발생한 기간에는 잠열속과 현열속에 의한 방출열량이 약 $100W/m^2$ 이상이다. 대설이 발생한 시기의 기압배치는 중국 북부 지방이나 중부 지방에 고기압이 위치하고, 동해상이나 일본 열도상에 저기압이 존재하여 서해 또는 한반도에서 전선이 형성되는 서고동저형의 특징을 보인다. 한편, 대설이 발생한 기간동안 서해 연안지역의 풍향은 북풍 또는 북서풍이 우세하고, 풍속은 $4\sim8m/sec$ 정도이다.

• 수산해양기술연구
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• 제51권4호
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• pp.567-575
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• 2015

Species composition in the coastal waters off Ulleungdo of Korea were examined based on catches bimonthly collected by trammel net in 2013. A total of 711 individuals and 181.9 Kg were caught and catches were composed of 4 classes 15 orders 27 families 52 species including 44 Pisces, 4 Gastropoda, 3 Cephalopoda, and 1 Echinodermata. The dominant species in biomass were File fish (Thamnaconus modestus), Atka mackerel (Pleurogrammus azonus), and Greenling (Hexagrammos otakii). Data were summarized using hierarchical cluster analysis (HCA) and detrended correspondence analysis (DCA) to examine similarity in species composition for each month, and community structure in Ulleungdo was divided into two groups. Community structures in February, April and December with low temperature and well-mixed surface water were distinguished from those in June, August and October with high temperature and strong stratification, which could be attributed to temporal changes in dominant species. Atka mackerel and Spear squid mainly caught in February and April, disappearing in June, August and October, and File fish outburst was shown in October. Because the water off Ulleungdo has been under low human pressure, it could be a good case study to elucidate effects of climate change on community structure and ecosystem in the East sea. Continuous surveys and further studies are required to demonstrate migration route and distribution of dominant species and long-term changes in community structure in the water of Ulleungdo.

• 한국세라믹학회지
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• 제44권12호
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• pp.696-702
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• 2007

The family of (Sr,Mg)-doped $LaGaO_3$ compounds, which exhibit high ionic conductivity at $600-800^{\circ}C$ over a wide range of oxygen partial pressure, appears to be promising as the electrolyte for intermediate temperature solid oxide fuel cells. Conventional synthesis routes of (Sr,Mg)-doped $LaGaO_3$ compounds based on solid state reaction have some problems such as the formation of impurity phases, long sintering time and Ga loss during high temperature sintering. Phase stability problem especially, the formation of additional phases at the grain boundary is detrimental to the electrical properties of the electrolyte. From this point of view, we focused to synthesize single phase (Sr,Mg)-doped $LaGaO_3$ electrolyte at the stage of powder synthesis and to apply relatively low heat-treatment temperature using novel synthesis route based on combustion method. The synthesized powder and sintered bulk electrolytes were characterized by XRD, TG-DTA, FT-IR and SEM. AC impedance spectroscopy was used to characterize the electrical transport properties of the electrolyte with the consideration of the contribution of the bulk lattice and grain boundary to the total conductivity. Finally, relationship between synthesis condition and electrical properties of the (Sr, Mg)-doped $LaGaO_3$ electrolytes was discussed with the consideration of phase analysis results.

• 에너지공학
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• 제12권1호
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• pp.1-10
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• 2003

가압유동층 연소 유닛은 1~1.5 MPa, 연소 온도 850~87$0^{\circ}C$ 조건으로 운전된다. 가압 석탄 연소 시스템은 전열관을 통한 열전달로 증기를 생산하며 가스터빈으로 공급될 고온 가스를 생산한다. 가스 중의 고체 잔류물에 의한 가스터빈의 성능 저하 때문에 가스 정제가 매우 중요하며 석탄과 흡수제 및 연소 공기를 가압하여야 하고 배가스와 회 제거 시스템에서는 감압을 해야 하기 때문에 운전이 다소 복잡하다. 증기터빈 대 가스터빈에서 생산되는 전력의 비율은 약 80:20이고 모든 부하 범위에서 연소기와 가스터빈이 서로 적절히 조화를 이루어야 하기 때문에 PFBC와 복합 사이클 발전 루트는 독특한 제어 방식을 갖는다. 유동층에 적용할 수 있는 가스의 최대 온도는 회 융점에 의해 제한을 받기 때문에 가스터빈은 일반 가스터빈에 비해 좀 특별하다고 할 수 있다. 회의 용융이 일어나지 않도록 하기 위한 최대 허용 가스 온도는 약 90$0^{\circ}C$이다. 가스터빈의 높은 압력비 때문에 압축시 인터쿨링을 사용하며 이는 상대적으로 낮은 터빈 입구의 온도를 상쇄하기 위한 것이다.