• 한국식품과학회지
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• 제21권2호
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• pp.203-211
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• 1989

근채류를 열풍건조할 경우 수축변형 및 표면 경화현상을 일으켜 품질변화를 수반하게 되므로 본 연구에서는 온도, 상대습도 및 풍속을 조절할 수 있고 건조중의 시료크기 변화를 측정할 수 있는 실험실 규모의 건조장치를 제작하여 무우 및 고구마의 건조특성과 수축특성에 영향을 미치는 외부 요인들에 대해 조사하였다. 건조속도는 무우 및 고구마 모두 항률건조기, 감률건조기, 감률건조 2단계 a 및 b의 4단계로 구분되어 나타났다. 수축속도 곡선은 각각 건조속도에 대응하여 기울기가 다른 4단계로 나타났으며 항률건조 기간에서는 수축속도가 서서히 증가하다가 감률건조 1단계에서 급격히 증가하였고 감률건조 2단계의 초기에 상당하는 점에서 최대에 달하였다. 또한 시료의 두께. 상대습도 및 초기 함수율 등은 표면적 수축에 큰 영향을 미쳤고 시료의 두께가 얇을수록, 그리고 상대습도 및 초기 함수율이 높을수록 평형 상태에서의 수축율은 증가하였다.

• Ocean Science Journal
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• 제41권4호
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• pp.235-244
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• 2006

Determining 'photosynthetically active radiation' (PAR) is a key part of calculating phytoplankton productivity in a biogeochemical model. We explore the daily and seasonal variability in the ratio of PAR irradiance to total irradiance that occurred at Ieodo Ocean Research Station (IORS) in the East China Sea under clear-sky conditions in 2004 using a simple radiative transfer model (RTM). Meteorological data observed at IORS and aerosol optical properties derived from Aerosol Robotic Network observations at Gosan are used for the RTM. Preliminary results suggest that the use of simple PAR irradiance-ratio values is appropriate in calculating phytoplankton productivity as follows: an average of $0.44\;({\pm}0.01)$ in January to an average of $0.48\;({\pm}0.01)$ in July, with average daily variabilities over these periods of about $0.016\;({\pm}0.008)$ and $0.025\;({\pm}0.008)$, respectively. The model experiments demonstrate that variations in the major controlling input parameters (i.e. solar zenith angle, precipitable water vapor and aerosol optical thickness) cause PAR irradiance ratio variation at daily and seasonal timescales. Further, increases (>0.012) in the PAR irradiance ratio just below the sea-surface are positively correlated with high solar zenith angles and strong wind stresses relative to those just above the sea-surface.

• 한국연초학회지
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• 제4권2호
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• pp.41-50
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• 1982

To investigate tile effects of growth characteristics on the yield, price per Kg, chemical contents and physical properties in Burley tobacco, ten varieties including Burley 21 were tested in this study. The results obtained are summarized as follows. 1 Forty to fifty days after transplanting, CCR (Crop Growth Rate) was the highest. RCR (Relative Growth Rate) increased up to 40 days, but decreased 50 days when maturation began. High- yielding varieties showed high CCR and RCR till 60 days. 2. Total alkaloid content of cured leaf increased about three times than that of topping stage, but the increased rates were some what different among varieties. 3. Leaf area, stalk diameter, stalk height and days to flower showed positive correlations to yield, whereas leaf thickness and weight per unit leaf area showed negative. 4 Varieties which are high in cured leaf weight ratio and weight per unit leaf thickeners showed relatively poor quality. 5 Nitrogen content was high in leafy and larger stalk diameter variety. 6. There are positive correlation between weight per unit leaf thickness and filling power. The time of combustion was positively correlated to leaf thickness and weight Per unit leaf. 7. It can be concluded that many characteristics are related to the yield, but not quality. It is, there fore, easy to Predict tile yield, but difficult to forecast the qualiffy.

• Journal of Electrical Engineering and Technology
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• 제7권4호
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• pp.576-581
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• 2012

A 23 W continuous wavelength $CO_2$ laser system exited by a high-frequency LCC resonant converter is adapted to cut a biodegradable rope fabricated with polybutylene succinate. As the biodegradable rope consists of three twisted strands, the thickness changes relative to the position of the laser beam and we thus propose a method to determine exact cutting depth. In order to obtain the parameters related to the rope cutting, the experimental and theoretical cutting depths are compared and analyzed for a range of laser heat sources. The melted thickness and groove width of the cut biodegradable rope are also examined. The proposed theoretical cutting depth depends on the incident power and target velocity ratio. From these experimental results, the biodegradable rope with a diameter of 22 mm can be cut with a heat source of 50 J/cm resulting in a melted thickness of 1.96 mm and a groove width of 0.65 mm. The laser system is shown to be perfect tool for the processing of biodegradable rope without the occurrence of raveling.

• 대한치과교정학회지
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• 제4권1호
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• pp.21-29
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• 1974

The purpose of the present study is to evaluate changes of the soft tissue relative to underlying skeletal elements during orthodontic treatment, and the influence of orthodontic treatment quantitatively on various regions of the facial profile. 59 Korean young women were selected, whose Hellman dental age was IV A, IV C and V A. Lateral cephalometric head films were taken before and after orthodontic treatment. From tracings, landmarks on skeletal and soft tissue profile were located, and then their linear and angular measurements were made directly. The results were obtained as follow: 1) Soft tissues of the facial profile were closely related and dependent on the underlying dentoskeletal frameworks. Orthodontic treament resulted in the reduction of dentofacial protrusion with both upper and lower lips becoming less procumbent during treament. 2) Thickness of the upper lip increased considerably during orthodontic treatment, and this change was related to maxillary incisor retraction. The ratio between the amount of maxillary incisor retraction and that of increment of upper lip thickness was approximately 5:3. 3) Soft tissue thickness overlying Downs' point A, point B and pogonion was not modified by orthodontic treatment. 4) Holdaway's H line, relating facial profile to the underlying dentoskeletal framework, seemed to be the most practical approach to soft tissue analysis.

• 한국도로학회논문집
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• 제16권1호
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• pp.31-39
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• 2014

PURPOSES : Surface treatment material for pavement preventive maintenance should be inspected field applicability. This study(Part II) aimed to checkup coating characteristics and performance analysis using lab and field tests. The hydrophobic - low viscosity filling material for pavement preventive maintenance is presented in Part I, which is a series of companion study. METHODS : Relative comparison between general asphalt mixtures and surface treatment asphalt mixtures are analyzed and measured for the field application such as indirect tensile strength ratio(TSR), abrasion resistance, crack propagation resistance, temperature resistance, coating thickness, permeability resistance and skid resistance in terms of british pendulum number(BPN). RESULTS : It is found that TSR, crack propagation resistance and permeability resistance is increased as against uncoated asphalt specimen. Abrasion resistance and temperature resistance is secured from the initial coating thickness point of view, which is about 0.2~0.3mm. Skid resistance on the surface treatment pavement is satisfied with the BPN criteria of national highway because of exposed aggregate and crack sill induced pavement deterioration and damage cracks. CONCLUSIONS : The hydrophobic - low viscosity surface treatment material for pavement preventive maintenance is validated on field applicability evaluation based on quantitative analysis of coating thickness and performance analysis using lab and field tests.

• 한국정보통신학회:학술대회논문집
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• 한국해양정보통신학회 2008년도 춘계종합학술대회 A
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• pp.117-120
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• 2008

본 논문은 차량 충돌방지 레이더의 허상방지용 전파흡수체를 유전손실재료인 $TiO_2$을 이용하여 개발하였다. 먼저 전파흡수체 샘플을 유전손실재료인 $TiO_2$ 와 바인더인 CPE를 사용하여 조성비별 제작하고, 네트워크 아날라이저를 이용하여 측정한 5-parameter로부터 1-Port Method를 이용하여 복소비유전율을 계산하였다. 그리고 계산된 복소비유전율을 이용하여 전파흡수체를 설계 및 제작한 결과 조성비 $TiO_2$:CPE=70:30 wt.%, 두께 1.85 mm, 주파수 76-77 GHz에서 20 dB 이상의 전파를 흡수하는 전파흡수체를 개발하였다.

• Journal of electromagnetic engineering and science
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• 제12권1호
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• pp.20-25
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• 2012

In this paper, the EM wave absorber for ETC system was designed and fabricated. We fabricated several samples in different composition ratios of flaked sendust and CPE(Chlorinated Polyethylene). Absorption abilities were simulated in accordance with different thicknesses of the prepared absorbers and changed complex relative permittivity and permeability according to composition ratio. The optimized mixing ratio of flaked sendust and CPE was found as 60 : 40 wt.% by experiments and simulation. Then the EM wave absorber was fabricated and tested using the simulated data. As a result, the developed EM wave absorber has the thickness of 2.75 mm and absorption ability was 22.5 dB in the case of normal incidence at 5.8 GHz. Therefore, it was confirmed that the newly developed absorber can be used for ETC system.

• Structural Engineering and Mechanics
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• 제61권3호
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• pp.389-396
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• 2017

Concrete pavements are subjected to traffic and environmental loadings. Repetitive type of such loading cause fatigue distress which leads to failure by forming cracks in pavement. Fatigue life of concrete pavement is calculated from the stress ratio (i.e. the ratio of applied flexural stress to the flexural strength of concrete). For the correct estimation of fatigue life, it is necessary to determine the maximum flexural tensile stress developed for practical loading conditions. Portland cement association PCA (1984) and Indian road congress IRC 58 (2015) has given charts and tables to determine maximum edge stresses for particular loading and subgrade conditions. It is difficult to determine maximum stresses for intermediate loading and subgrade conditions. The main purpose of this study is to simplify the analysis of rigid pavement without compromising the accuracy. Equations proposed for determination of maximum flexural tensile stress of pavement are verified by finite element analysis.

• 한국의류학회지
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• 제14권1호
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• pp.44-54
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• 1990

The purpose of this study was to investigate the effects of thickness of the sleeping pad on the physiological responses and the microclimate in the heating ondol room during sleeping time. The measuring points were skin temp., weight loss and body movement as physiological responses and the compression ratio, the temp. on/under the sleeping pad, the inside limp. of the sleeping quilts and subjective sence while 7 hours sleeping. Thickness of sleeping pads was 27.2 mm(A), 34.8 mm (B), 47.9 mm(C) used for 90 days and no used pad 60.7 mm(D). The floor surface temp. was keeping $29{\pm}1^{\circ}C$ while the environmental conditions was at $23{\pm}1^{\circ}C$ ($50{\pm}5\%$ R.H.) The results were as followings; 1) The mean compression ratio after using the sleeping pads for 45 days was about $70\%$ , and it wasn't increased any more thereafter 2) After 2 hours sleeping the temp. under the sleeping pads was shown that C and D were higher than A and B, and the temp. on the sleeping pads was shown that A and C pads were higher than B and D. But after 3-4 hours sleeping the skin temp. of legs was shown that B and D pads were higher than A and C. 3) Weight loss for C pad was significantly higher than others. Body movement and side position in tying was higher in A and C pads than B and D. 4) The inside temp. of quilt for A and C pads were higher in the early part of sleeping period than those of B and C pads and relative humidity was lower in C than others. 5) D pad was softer than others and fatigue degree was turned out to be lowest in D, the highest in A. From this point of view, we concluded that thickness of the sleeping Pad in the heating ondol room had different characteristic from that in no heating ondol room. And 35 mm used pad was turned out to be proper.