• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2009년도 9th International Meeting on Information Display
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• pp.1554-1556
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• 2009

In this paper, we propose a system to adjust specific color of image. The HSV of R/Y/G/C/B/M regions can be modified individually. The color reproduction can be preferred color, true color, or stander color for customer requirement.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2007년도 7th International Meeting on Information Display 제7권1호
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• pp.293-296
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• 2007

Gamma curve is one of the most important optical performance characteristics of a liquid crystal display. we present investigations on the relationship between gamma and polarizer. The gamma curve is affected by the angle of the polarizer absorption axis. When the crossed angle between the two polarizers turns larger, gamma values will decrease. The gamma variation caused from each polarizer variation could be improved by monitoring and controlling the axial direction of the polarizers.

• 대한수의학회지
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• 제26권1호
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• pp.175-185
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• 1986

The measurement of angled erythrocyte sedimentation rate (ESR), as a replacement for perpendicular ESR, for cattle blood was scrutinized since it has been well known that perpendicular ESR in cattle is too slow to be adopted as an effective clinical test. Samples of blood were taken from 186 Korean native cattle over 2 years old. The results obtained in the experiment were summarized as follows. 1. Average values of perpendicular ESR/24hrs in 15 apparently healthy cattle, as measured by Wintrobe, Westergren and capillary tubes, were $5.8{\pm}2.2$, $11.1{\pm}3.7$ and $10.4{\pm}4.5%$ respectively, which were found to be similar to the values of perpendicular ESR/hr of normal blood of human. 2. The ESR was determined in the tubes held at 90, 75, 60, 45, 30 and 15-degree angles, using 3 types of tubes. For the diagnostic purposes, the best results were obtained from the tubes held at 45-degree angle. 3. The angled ESR values increased as the diameters of the tube-bores decreased. 4. The tube length did not affect the angled ESR(%). 5. The angled ESR values increased with the increased environmental temperature during the ESR measurement. 6. The storage temperature at $5^{\circ}C$, $20^{\circ}C$ and $35^{\circ}C$, of the blood for 24 hours did not affect the angled ESR. 7. Samples of blood were treated with 4 kinds of anticoagulants (heparin, $K_2$-EDTA, double oxalate and sodium citrate) and the ESR was determined at 45-degree angle, using capillary hematocrit tubes. The ESR values were higher in the blood samples treated with sodium citrate than in those treated with other anticoagulants. 8. By using the autologous plasma, the PCV was adjusted to be 5, 10, 20, 30, 40 and 50ml/100ml and the ESR was determined in the capillary hematocrit and Wintrobe tubes held at 45 degrees. In both of the methods the ESRs increased as the values of PCV decreased. The regressions of ESR to PCV in both 45-degree-angled capillary and Wintrobe tubes were curvilinear. For the capillary hematocrit tubes the second degree polynomial $Y=61.9779-2.3533x+0.0228x^2$ (r=0.9999) fits the data. And in the case of Wintrobe tubes the second degree polynomial $Y=27.9767-1.1314x-0.0117x^2$ (r=0.9998) fits the data. 9. The 45-degree angled ESR was determined in the blood of 71 healthy Korean native cows using capillary hematocrit tubes. The average PCV was $35.4{\pm}3.6ml/100ml$. The observed ESR/hr averaged $7.2{\pm}2.7%$, while the corrected ESR/hr to a PCV of 36ml/100ml averaged $6.6{\pm}1.3%$. From these results it was concluded that to obtain the best results the ESR/hr of Korean native cattle should be determined at 45-degree angle at room temperature($20^{\circ}C$) using capillary hematocrit tubes.

• Composites Research
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• 제27권2호
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• pp.37-41
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• 2014

섬유강화복합재료는 비강도와 비강성이 뛰어나 여러 분야에 걸쳐 사용량이 증가하고 있으며 자전거와 같은 스포츠 용품에도 사용량이 점점 증가하고 있다. 복합재료는 다양한 형상의 구조부품으로 만들어져 사용되고 있다. 특히 자전거 프레임의 일부에는 사각형 복합재 튜브 형태로 제작되어 사용되고 있으나 이에 관한 연구는 많지 않다. 사각 복합재 튜브의 경우에 모서리에 적절한 라운드 값을 주어 굽힘과 비틀림에 견디도록 설계된다. 본 연구에서는 모서리의 곡률반경이 R5, R10, R15인 세 개의 그룹에 가로-세로 1:1, 1:1.5, 1:2의 형상비를 갖는 아홉 종류의 사각 복합재 튜브를 제작하였다. 탄소섬유강화복합재료가 튜브제작에 사용되었으며 단면적은 모두 같도록 설계되었다. $[0/90/{\pm}45]s$으로 적층하여 제작한 사각 복합재 튜브에 굽힘과 비틀림 하중을 가하여 실험평가를 수행하였다. 실험결과 사각 복합재 튜브의 R 값과 형상비에 따라서 굽힘 및 비틀림 특성이 크게 다름을 알 수 있었다.

• 대한기계학회논문집B
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• 제37권2호
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• pp.187-196
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• 2013

화력발전용 관류보일러 화로벽관에서의 밀도파 불안정 예측을 목적으로 수치모델을 개발하였다. 시간 도메인에서 1 차원 유한체적법을 적용하여 관내 비정상상태의 유동장을 계산하였으며, 화로벽관의 평행관 연결을 모사하기 위해 헤더의 모델도 포함하였다. 평행관들 가운데 하나의 관에 열 섭동을 부가 후 관 입출구 유량의 변동을 관찰함으로써 밀도파 불안정을 찾았다. 개발된 모델은 문헌의 실험결과와 검증을 거쳐 700MW 보일러 화로벽관에 적용하였다. 그 결과 Takitani 의 실험결과에서는 평행으로 연결된 우회 유량이 줄어들수록 불안정 경계 열량이 상승하는 경향이 있었던 반면, 보일러 화로벽관의 경우에는 평행관 모델링에 크게 영향을 받지 않음을 확인하였다.

• Composites Research
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• 제15권1호
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• pp.53-60
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• 2002

본 연구에서는 내열 특성과 구조적인 특성을 갖는 탄소섬유/페놀릭 복합재 내열튜브를 필라멘트와인딩 공법에 의해 제작하고 이들의 구조적인 성능을 평가하였다. 이를 위해 내열튜브의 제작방법을 소개하고 황산용해법을 적용하여 내열튜브에서의 섬유체적비와 기공함유율을 측정하였다. 시편폭을 달리한 인장시편의 기계적 특성을 평가함으로써 강화섬유의 연속성을 나타낼 수 있는 시편형상을 제시하였으며 공정변수를 달리한 내열튜브에서 채취된 인장시편의 기계적 특성을 평가함으로써 내열튜브의 제작을 위한 적절한 공정조건을 결정하였다. 그리고 보증시험을 통해 수집한 음향신호의 분석을 통해 내열튜브에서의 균열진전과 파손양상을 조사하였다. 마지막으로 내열튜브 자체에 대해 보증시험과 파열시험을 수행함으로써 내열튜브 자체의 구조적인 신뢰성을 확인하였다.

• 한국생산제조학회지
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• 제22권3_1spc호
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• pp.573-579
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• 2013

Once-through helically coiled steam generator tubes subjected to external pressure are of interest because of their application to advanced small- and medium-sized integral reactors, in which a primary coolant with a relatively higher pressure flows outside the tubes, while secondary water with a relatively lower pressure flows inside the tubes. Another notable point is that the values of the mean radius to thickness ratio of these steam generator tubes are very small, which means that a thick-walled cylinder is employed for these steam generator tubes. In the present paper, the maximum allowable pressure of helically coiled and thick-walled steam generator tubes with through-wall cracks under external pressure is investigated based on a detailed nonlinear three-dimensional finite element analysis. In terms of the crack orientation, either circumferential or axial through-wall cracks are considered. In particular, in order to quantify the effect of the crack location on the maximum external pressure, these cracks are assumed to be located in the intrados, extrados, and flank of helically coiled cylinders. Moreover, an evaluation is also made of how the maximum external pressure is affected by the ovality, which might be inherently induced during the tube coiling process used to fabricate the helically coiled steam generator tubes.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2005년도 추계학술대회 논문집
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• pp.71-74
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• 2005

In manufacturing automotive parts, such as engine cradles, frame rails, subframes, cross-members, and other parts from circular tubes, pre-bending and pre-forming operations are often required prior to the subsequent tubular hydroforming process. During some pre-forming operations, the cross section of a bent circular tube is crushed into an oval-like shape to ensure proper geometry and sufficient clearance in the hydroforming dies. For such applications, the use of oval Instead of circular tubes could be an effective means of eliminating the pre-forming step. The oval tube could also be produced with less thinning and with less strain on the outside of the bend when controlled by a booster system without the use of mandrel. Hence, the understanding of the issues that occur in the bending of oval tubes is worthy of Investigation. This paper presents parametric studies on the bending of oval tubes without a mandrel. The finite element modeling technique is used to examine the deformation characteristics for both circular and oval tubes. In the simulations, the bending process parameters of bend radius, aspect ratio of the tube ovalness, and tube wall thickness are varied. Observations are made to obtain a hoop-buckle limit diagram in terms of a non-dimensional shape degradation factor. Suggestions based upon developed criteria are made on the acceptability of bend tubes suitable for hydroforming applications without the need ofa pre-forming step or the used of a mandrel.

• 수산해양기술연구
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• 제34권2호
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• pp.212-222
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• 1998

Heat transfer performance improvement by fin and groovs is studied for condensation of R-11 on integral-fin tubes. Eight tubes with trapczodially shaped integral-fins having fin density from 748 to 1654fpm(fin per meter) and 10, 30 grooves are tested. A plain tube having the same diameter as the finned tubes is also used for comparison. R-11 condensates at saturation state of 32 $^{\circ}C$ on the outside tube surface coded by inside water flow. All of test data are taken at steady state. The heat transfer loop is used for testing singe long tubes and cooling is pumped from a storage tank through filters and folwmeters to the horizontal test section where it is heated by steam condensing on the outside of the tubes. The pressure drop across the test section is measured by menas pressure gauge and manometer. The results obtained in this study is as follows : 1. Based on inside diameter and nominal inside area, overall heat transfer coefficients of finned tube are enhanced up to 1.6 ~ 3.7 times that of a plain tube at a constant Reynolds number. 2. Friction factors are up to 1.6 ~ 2.1 times those of plain tubes. 3. The constant pumping power ratio for the low integral-fin tubes increase directly with the effective area to the nominal area ratio, and with the effective area diameter ratio. 4. A tube having a fin density of 1299fpm and 30 grooves has the best heat transfer performance.

• 한국철도학회논문집
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• 제12권4호
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• pp.590-596
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• 2009

본 연구에서는 탄소, 유리, 케블라 및 탄소-케블라 하이브리드 섬유로 제작된 원형튜브를 이용하여 각 소재별 에너지 흡수특성과 파손메커니즘을 규명하였다. 이를 위해 각 튜브에 대한 10mm/min의 준정적 압축시험을 수행하였다. 시험결과 탄소섬유 튜브가 가장 에너지 흡수특성이 우수했으며 탄소-케블라 하이브리드 섬유 튜브가 가장 낮은 에너지 흡수율을 보였다. 또한, 각 소재별 에너지 흡수메커니즘을 분석한 결과 탄소 및 유리섬유튜브는 취성파괴 모드로 압축되었다. 또한, 케블라 섬유 튜브는 국부좌굴에 의한 접힘모드가 지배적이고, 탄소와 케블라 하이브리드 섬유 튜브의 경우 단층굽힘과 국부좌굴모드가 혼합되어 나타났다.