• Journal of the Korean Wood Science and Technology
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• 제38권2호
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• pp.117-123
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• 2010

The objective of this research was executed to investigate the effect of molar ratio of formaldehyde to urea and melamine (F/(U+M)) of urea-melamine-formaldehyde (UMF) resin on bonding high and low moisture content veneers. For that purpose, UMF resin types with 5 different F/(U+M) molar ratios (1.45, 1.65, 1.85, 2.05, and 2.25) synthesized were used in present study. First, their curing behavior was evaluated by differential scanning calorimetry. Second, their adhesion performance in bonding high and low moisture content veneers was evaluated by probe tack and dry and wet shear strength tests. Curing temperature and reaction enthalpy decreased with the increase of F/(U+M) molar ratio. And the dry and wet shear strengthsof plywood manufactured from low moisture content veneers were higher than thoseof plywood manufactured from high moisture content veneers. Also, the maximum initial tack force on the low moisture content veneer was higher than that on the high moisture content veneer.

• Journal of the Optical Society of Korea
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• 제17권4호
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• pp.317-322
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• 2013

We have proposed and demonstrated a low numerical aperture technique to measure the depth of through silicon vias (TSVs) using white-light scanning interferometry. The high aspect ratio hole like TSV's was considered to be impossible to measure using conventional optical methods due to low visibility at the bottom of the hole. We assumed that the limitation of the measurement was caused by reflection attenuation in TSVs. A novel interference theory which takes the structural reflection attenuation into consideration was proposed and simulated. As a result, we figured out that the low visibility in the interference signal was caused by the unbalanced light intensity between the object and the reference mirror. Unbalanced light can be balanced using an aperture at the illumination optics. As a result of simulation and experiment, we figured out that the interference signal can be enhanced using the proposed technique. With the proposed optics, the depth of TSVs having an aspect ratio of 11.2 was measured in 5 seconds. The proposed method is expected to be an alternative method for 3-D inspection of TSVs.

• Journal of Nutrition and Health
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• 제17권1호
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• pp.20-30
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• 1984

This experiment was designed to investigate the effects of the mixing ratio of soyprotein and casein, and the level of pectin combined with the mixture on lipid metabolism in rats. Forty-eight male weanling rats of Wistar strain weighing 58.8\;{\pm}\;1.9g$ were divided into six groups by completely randomized block design and fed 10% protein diet for four weeks. Two types of protein mixtures (casein to soyprotein mixing ratio of 1 : 3 and 2: 1)combined with 0.5% , 3%, and 5% of pectin were employed for experimental diets. The results obtained in the study are summarized as follows ; 1) Feed efficiency ratio and protein efficiency ratio were not significantly different among six groups for the whole experimental period, but those for high casein-low pectin group were significantly higher than the ones for high soy-high pectin group at 4th week of the experimental period. 2) Gross fecal dried weight and fecal lipid excretion were higher in high pectin groups of both protein combinations. Therefore, the apparent fat digestibility and absorption appeared to be significantly low in high pectin groups. 3) Pectin was effective in lowering serum lipid and cholesterol levels in high casein groups, but no effect of pectin was noted in high soyprotein groups. 4) Lipid and cholesterol contents of the liver were higher in high soy-low pectin group than the others. And no marked differences in lipid and cholesterol contents in the kidney and carcass were observed.

• Journal of Biosystems Engineering
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• 제24권3호
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• pp.259-266
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• 1999

This research was carried out to investigate the possibility of real time rice milling ratio measurement using the spectral reflection characteristics. In this study, various methods were compared such as \circled1 using the whiteness meter, \circled2 using the colorimeter, \circled3 using the Visible and the NIR reflection spectrum. The samples were milled in the domain of 84~96% by 0.5% interval classified by milling ratio. The NMG treatment method required about 20 minutes to determine the milled ratio and r2 was 0.0028 to 0.7959 that was very low. In case of whiteness meter, r2 was high but speed of measurement was 5 minutes that was very low. Measurement with the colorimeter required about 5 minutes and r2 was 0.60 to 0.85 that was low. The reflection spectrum were measured in the range of 400~2,500nm with 2nm interval and the MLR model with six-wavelength obtained from first derivative of spectra gave the best results(r2 = 0.967, SEP = 0.729%)

• 한국진공학회:학술대회논문집
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• 한국진공학회 2011년도 제40회 동계학술대회 초록집
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• pp.472-472
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• 2011

The capacitive coupled plasma (CCP) has been extensively used in the semiconductor industry because it has not only good uniformity, but also low electron temperature. But CCP source has some problems, such as difficulty in varying the ion bombardment energy separately, low plasma density, and high processing pressure, etc. In this reason, dual frequency CCP has been investigated with a separate substrate biasing to control the plasma parameters and to obtain high etch rate with high etch selectivity. Especially, in this study, we studied on the etching of $SiO_2$ by using the pulse-time modulation in the dual-frequency CCP source composed of 60 MHz/ 2 MHz rf power. By using the combination of high /low rf powers, the differences in the gas dissociation, plasma density, and etch characteristics were investigated. Also, as the size of the semiconductor device is decreased to nano-scale, the etching of contact hole which has nano-scale higher aspect ratio is required. For the nano-scale contact hole etching by using continuous plasma, several etch problems such as bowing, sidewall taper, twist, mask faceting, erosion, distortions etc. occurs. To resolve these problems, etching in low process pressure, more sidewall passivation by using fluorocarbon-based plasma with high carbon ratio, low temperature processing, charge effect breaking, power modulation are needed. Therefore, in this study, to resolve these problems, we used the pulse-time modulated dual-frequency CCP system. Pulse plasma is generated by periodical turning the RF power On and Off state. We measured the etch rate, etch selectivity and etch profile by using a step profilometer and SEM. Also the X-ray photoelectron spectroscopic analysis on the surfaces etched by different duty ratio conditions correlate with the results above.

• Tribology and Lubricants
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• 제20권2호
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• pp.68-76
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• 2004

Applying a general Galerkin FE lubrication analysis method to spiral groove dry gas seals, this study intends to analyze in detail the effects of groove design parameters, such as a spiral angle, groove width ratio, groove radius ratio, groove depth ratio, and groove taper ratio, on the lubrication performances of an opening force, leakage, axial stiffness and damping, and angular stiffness and damping at low and high rotating speeds: 3,600 and 15,000 nm. Results show that, for the primary design consideration performances such as the opening force and axial and angular stiffnesses, a spiral angle of $25^{\circ}$, a groove width ratio of 0.46, a groove radius ratio of 1.1, a groove depth ratio of 1.0, and a groove taper ratio of 0.0 are preferred. Where the recommended relatively low values of groove depth and taper ratios are to keep the axial and angular dampings positive or higher than 0 particularly at the high rotating speed.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2007년도 추계학술대회 논문집
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• pp.302-305
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• 2007

In recent years, many researches on new storage media with high capacity and information are developing. For manufacture of optical storage with high capacity, the injection molding process is generally used. In order to increase the filling ratio of the injection molding structure, the injection molding process required for high injection pressure, packing pressure and temperature control of the mold. However, conventional injection molding process is difficult to increase the filling ratio using injection master with the range of several nanometers and high aspect ratio. In order to improve and increase filling ratio of nano-structure with high aspect ratio, the active temperature control of injection mold was used. Experimental conditions were used injection pressure, time and temperature. Consequently, by using the peltier device into injection mold, we carried out the efficient and active temperature control of mold at low cost.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 1998년도 봄 학술발표회 논문집(I)
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• pp.69-74
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• 1998

Concrete has a many problems to apply high rise building of its low strength to weight and low ductility, compared to steel products. Therefore, it is necessary to make high strength concrete for applying to night rise building. In the experiment, the high strength concrete was made in variable of unit weight of binder, water to binder ratio(W/B), and sand to aggregate ratio(S/a) using batcher plant. As a result, it was possible to make high strength concrete using only materials for ordinary concrete without admixtures such like silica fume in batcher plant.

• 대한기계학회논문집A
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• 제25권11호
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• pp.1767-1776
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• 2001

For the stable operation of high speed air spindle, the low rotational inertia and high damping ratio of spindle shafts as well as high fundamental natural frequency are indispensable. Conventional steel spindles are net appropriate for very high speed operation because of their high rotational inertia and low damping ratio. In this study, a high speed spindle composed of carbon fiber epoxy composite shaft and steel flange was designed for maximum critical speed considering minimum static deflection and radial expansion due to bending load and centrifugal force during high speed relation. The stacking angle and the stacking thickness of the composite shaft and the adhesive bonding length of the 7teel flange were selected through vibrational analysis considering static and thermal loads due to temperature rise.

• 말소리와 음성과학
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• 제14권3호
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• pp.87-101
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• 2022

대전·충남지역 20-30대 여성 언어재활사 50명을 대상으로 주관적 음성 피로도 설문과 더불어 하루 4회기를 기준으로 언어치료 전/후 음성 샘플 수집을 하였다. 연구 결과, Korean Vocal Fatigue Index의 음성 피로로 인한 음성 사용회피 항목과 음성 사용으로 인한 신체 피로 항목에서 피로 집단과 피로 없는 집단 간 유의한 차이가 있었다. 두 집단의 음향음성학적 특성과 관련하여, 두 집단 모두 치료 후 저주파 대역 에너지가 상대적으로 낮아지고 고주파 대역 에너지가 상승하는 패턴을 보였다. 이러한 특징이 분산분석 결과, 주 효과로 나타난 low to high-ratio[t1(time.1)>t2(time.2)], slope_ltas(t2>t1), 3rd formant's energy(t1>t2), high energy(t2>t1) 등에 잘 반영되어 있다. 집단 간 차이는 음향변수들 중 치료 전 모음 연장발성 스펙트럼 저주파 대역의 에너지인 low energy에서만 관찰되었고 피로 없는 집단의 값이 더 컸다(no.fatigue>fatigue in t1). 음향변수에서의 이러한 특징과 더불어 치료 세션 후 피로 없는 집단의 연결발화에서의 왜도 증가는 장시간의 목소리 노동으로 인한 성대 과긴장(higher muscle tonus)과 목소리 남용 때문으로 해석할 수 있다. 섭동변수 shimmer_local은 피로 없는 집단이 언어치료 후 낮아졌고(t1>t2), 켑스트럼 변수인 RNR(rhamonics to noise ratio)은 언어치료 후 값이 높아졌다(t2>t1). NHR(noise to harmonic ratio)은 두 집단 모두 치료 후 낮아졌다. NHR의 감소와 shimmer_local의 하강은 치료 세션을 진행하면서 발성 과정이 안정화되었거나 혹은 전문 지식이 있는 언어재활사(특히 피로 없는 집단)들의 효율적 목소리 사용이 기여했다고 결론지을 수 있다. 피로 없는 집단의 경우는 치료 후에 RNR값이 유의하게 커졌으므로 치료 후 오히려 조화음(harmonic) 구조가 더 안정되었다고도 말할 수 있을 것이다.