• 대한기계학회:학술대회논문집
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• 대한기계학회 2001년도 춘계학술대회논문집D
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• pp.840-845
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• 2001

Development of a small gas-turbine combustor for 100kW class APU(Auxiliary Power Unit) has been performed. This combustor is a reverse-annular type and has a tangential swirler in the liner head to improve the fuel/air mixing and flame stability. Three main and three pilot fuel injectors of the simplex pressure-swirl type are used. The performance target at the design condition includes a turbine inlet temperature of 1170K, a combustion efficiency of 99%, a pattern factor of 30%, and an engine durability of 3000 hours. Under developing the combustor, we conducted performance test of our first prototype(TS1) with some variants. As a result of the test, the performance targets of the combustor are satisfied except that the pattern factor is about 4% higher than target value. So, we redesigned the second prototype(TS2) and conduct performance test with the critical focus on pattern factor and exit mean temperature. We adopted TS2 four variant to check the improvement of pattern factor. As the result, the pattern factors of several variants were satisfied with the performance target. Finally, We chose the TS2A variant as a final combustor for our APU model.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2001년도 춘계학술대회논문집D
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• pp.858-863
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• 2001

In this paper, the test and result of flow and combustion for 21AFR lean fuel models are described. The necessity to develop the low emission combustor has been issued from the concern on the increase of green house and the destruction of ozone layer. To evaluate the flow and combustion performance of new designed 21AFR lean modules, the hydraulic tests in stereo lithographic airflows models, the low pressure combustion tests in three injectors model for weak extinction and ignition and the high pressure combustion tests in single sector for NOx, SAE and efficiency are performed. The low pressure tests reveal that the governing parameters in weak extinction and ignition at atmospheric condition are prefilmer length, swirl flow rotation direction, secondary swirl angle and flow split. As a results of combustion test at high pressure, the efficiency and smoke level are satisfied with performance targets, but EINOx of 17.8 is higher than target value of 13.1. The high pressure tests show that the main parameters influenced on NOx are primary swirl angle, swirl flow rotation direction, heatshield exit angle and liner mixing hole location.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2012년도 추계 학술논문 발표대회
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• pp.263-264
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• 2012

In this study, the ultra high strength concrete which have 100, 150, 200MPa took the heat from 20℃ to 70 0℃ and the 0, 20% stress in normal condition's to evaluate stress-strain, residual compressive strength and thermal expansion deformation were evaluated. The heating speed of specimen was 0.77℃/min 20~50℃, 50℃ before the target temperature, and the other interval's heating speed was 1℃/min. As a result, the stress-strain curve of non-load specimen showed the liner behavior at high temperature when the specimen's strength increased more. If ultra high strength concrete got loads, its compressive strength tended to decrease different from the normal strength concrete. The thermal expansion deformation was expanded from a vitrification of quartz over 500℃. however, over the 600℃, it was shrinked because of the dehydration of the combined water.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2010년도 추계 학술발표회
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• pp.1314-1321
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• 2010

The west express way which links south west area of the central city of Seoul has been notorious for extremely heavy traffics since its first opening in 1991(i.e. the average vehicle speed is less than 25km/h, a daily traffic is 112,000 and among them, more than 94% of the vehicles are the light vehicles). The city government recently initiated a new BTO(Build-Transfer-Operate) project as an alternative in releasing heavy traffic and a high construction cost. The proposed underground express road is the first double-level tunnel (i.e. a total length of road is 10,91km and the tunnel is 9.308km long) ever built in South Korea, while such tunnel system is not new worldwide as such A86 East tunnel in France, SMART tunnel in Malaysia, and Fuxing tunnel in China. This paper discusses major design issues regarding the internal structures such as deck slab, and secondary liner.

• 한국음향학회:학술대회논문집
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• 한국음향학회 2004년도 춘계학술발표대회 논문집 제23권 1호
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• pp.41-44
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• 2004

본 논문에서는 한국어에만 나타나는 경음에 대하여 음운학적, 음향학적 특성을 고찰하고 이를 기반으로 음성인식 실험을 수행한 후 그 결과를 분석하였다. 음성인식 실험을 위하여 입력 음성을 48개의 유사음소단위 (PLU; Phoneme Likely Unit)로 레이블링을 한 후 각각의 음소군에 대하여 LPC (Liner Predictive Coding) 분해능을 증가시키면서 음소인식 및 단어인식 실험을 수행하였다. 그 결과, 음소 인식 실험에서 경음군의 인식률이 가장 낮게 나타나 경음에 대한 분석이 보다 많이 필요함을 알 수 있었다. 또한 PLC의 분해 차원이 23차 일 때 경음과 전체 음소 인식률이 각각 $34.11\%,\;46.1\%$로 나타나 가장 양호함을 알 수 있었으며 단어인식 실험에서도 LPC 23차와 25차 일 때 $81.68\%,\;81.87\%$로 인식률이 가장 좋음을 알 수 있었다. 이상의 실험 결과에서 한국어의 경음은 전체 시스템의 인식 성능과 밀접한 관계가 있음을 알 수 있었다.

• 한국윤활학회:학술대회논문집
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• 한국윤활학회 2004년도 학술대회지
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• pp.355-361
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• 2004

Ceramic femoral heads in the total hip replacement have been developed to reduce the polyethylene liner wear, Alumina and zirconia (3Y-TZP) having the excellent tribological properties are coupled against acetabular cups of polyethylene and are used in clinical application worldwide. However, alumina has a risk of catastrophic failure, and zirconia has the low temperature degradation in spite of enhanced fracture toughness. Recently, novel zirconia/alumina composite is very attractive due to the low temperature degradation (LTD)-free character and high fracture toughness. In the present study, we focus on the wear of ceramic on ceramic, which are able to be used as femoral heads and acetabular cups. Therefore, LTD-free zirconia/alumina composites with three compositions are made in a form of disk and cylinder, and the wear of the composites is performed on pin-on-disk type wear tester. The wear is conducted with or without lubricant. All the composites fabricated with the different composition show the good wear resistance.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2001년도 춘계학술대회 논문집
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• pp.20-23
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• 2001

Hypereutectic Al-25Si alloy, which is expected to be applied to the cylinder-liner-part of the engine-block of an automobile due to its excellent wear resistance, low density and low thermal expansion coefficient, has been fabricated through a spray forming process. The obtained microstructure of the hypereutectic Al-25Si alloy appeared to consist of Al matrix and equiaxed Si particles of average diameter of 5-7 mm. To characterize the deformation behavior of this alloy, a series of load relaxation and compression tests have been conducted at temperatures ranging from RT to $500^{\circ}C$. The strain rate sensitivity parameter (m) of this alloy has been found to be very low (0.1) below $400^{\circ}C$ and reached maximum value of about 0.2 at $500^{\circ}C$. During the deformation above $300^{\circ}C$ in compression, strain softening has been observed. The diagram of extrusion pressure vs. ram-speed has been constructed. The extrusion has been successfully conducted at the temperatures of $300^{\circ}C$ and above with the ratio of area reduction of 28 and 40 in this study.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2005년도 제25회 추계학술대회논문집
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• pp.335-340
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• 2005

액체 로켓엔진 연소기에 적용되는 분사기 형상에 따른 연소특성 변화를 알아보기 위해 연소시험을 수행하였다. 사용된 분사기는 동축와류형으로서 챔버 와류실의 유무와 노즐 길이에 의한 특성변화에 초점을 맞추었다. 챔버 와류실의 유무에 따라 닫힘형과 열림형으로 구분이 된다. 노즐 길이에 따른 변화는 산화제와 연료가 분사되는 노즐을 증가시킨 분사기를 통해 이루어졌다. 연소기는 분사기가 한 개만 장착된 단일분사기 헤드, 내열재 형식의 연소실, 냉각 유로를 가진 동 재질의 노즐로 구성되어 있으며 연소실과 노즐의 외부는 스테인레스 스틸로 이루어졌다.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2005년도 제25회 추계학술대회논문집
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• pp.479-483
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• 2005

BBU(Base Bleed Unit)는 155mm 탄에 부착되어 비행 중에 형성되는 탄저부 항력(Base drag)을 감소시켜 사거리를 연장시키는 무기 체계로 국내에서는 2000년 이후 양산화 되었다. 본 연구는 항력감소제용 저연소속도 추진제의 원료 조성 변화를 통한 공정 Lead time 단축으로 생산성을 향상시키는데 목적이 있으며 개발 과정은 추진제 및 연소방지제의 조성시험을 통한 기본적인 특성 확인을 거친 후 Spin Test 와 실제 발사시험을 통해서 최종 성능을 확인하는 순서로 진행하였다.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2001년도 춘계학술대회 논문집 반도체재료
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• pp.38-41
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• 2001

In this work, we have been studied the characteristics of each nitride film for the optimization of PMD(pre-metal dielectric) liner nitride process, which can applicable in the recent semiconductor manufacturing process. The deposition conditions of nitride film were splited by PO (protect overcoat) nitride, baseline, low hydrogen, high stress and low hydrogen, respectively. And also we tried to catch hold of correlation between BPSG(boro-phospho silicate glass) deposition and densification. Especially, we used FTIR area method for the analysis of density change of Si-H bonding and Si-NH-Si bonding, which decides the characteristics of nitride film. To judge whether the deposited films were safe or not, we investigated the crack generation of wafer edge after BPSG densification, and the changes of nitride film stress as a function of RF power variation.