• Fisheries and Aquatic Sciences
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• 제5권3호
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• pp.183-190
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• 2002

To determine the effect of body size on the clearance rate and ingestion rate of small intertidal bivalves, Glauconome chinensis, feeding experiments were conducted on individuals of 12 different size classes, from 4 to 16 mm in shell length. Relationships between morphological parameters were also determined. The clearance and ingestion rates of G. chinensis responded similarly to their body size, ranging from 1.3 to 28.2 mL/hr/ind. and from 24.0 to 458.5, ${\mu}gC/hr/ind$., respectively. Both rates increased significantly (p<0.001) as shell length increased from 4 to 9 mm, although neither rate changed significantly when shell length was in the range from 12 to 16 mm. The weight-specific clearance rate $(CR_w)$ and ingestion rate $(IR_w)$ decreased with increasing body size, with values from 1.0 to 3.1 L/hr/g and from 17.9 to 51.3 mgC/hr/g, respectively. The $CR_w$ of G. chinensis was intermediate compared to those of larger bivalve species. The clearance rate (CR) relative to flesh dry weight (FDW) of G. chinensis were fitted well to the power function: $CR=0.43\times(FDW)^{0.71}\;(r^2=0.89)$. The exponent of fitting equation (0.71) of G. chinensis was higher than those of Mytilus edulis (Walne, 1972), Crassostrea gigas (Walne, 1972), and Placopecten magellanicus (MacDonald and Thompson, 1986).

• Journal of Electrical Engineering and Technology
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• 제9권5호
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• pp.1686-1693
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• 2014

In this paper, oil-paper samples composed of transformer windings were used to investigate the insulation degradation process subjected to partial discharge (PD), with artificial defects inside to simulate the PD induced insulation degradation. To determine appropriate test voltages, the breakdown time obtained through a group of accelerated electrical degradation tests under high voltages was firstly fitted by two-parameter Weibull model to acquire the average breakdown time, which was then applied to establish the inverse power law life model to choose advisable test voltages. During the electrical degradation process, PD signals were synchronously detected by an ultra-high frequency (UHF) sensor from inception to breakdown. For PD analysis, the whole degradation process was divided into ten stages, and chaos theory was introduced to analyze the variation of three chaotic parameters with the development of electrical degradation, namely the largest Lyapunov exponent, correlation dimension and Komogorov entropy of PD amplitude time series. It is shown that deterministic chaos of PD is confirmed during the oil-paper degradation process, and the obtained results provide a new effective tool for the diagnosis of degradation of oil-paper insulation subjected to PD.

• Wind and Structures
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• 제24권6호
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• pp.579-611
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• 2017

Bora is a strong, usually dry temporally and spatially transient wind that is common at the eastern Adriatic Coast and many other dynamically similar regions around the world. One of the Bora main characteristics is its gustiness, when wind velocities can reach up to five times the mean velocity. Bora often creates significant problems to traffic, structures and human life in general. In this study, Bora velocity and near-ground turbulence are studied using the results of three-level high-frequency Bora field measurements carried out on a meteorological tower near the city of Split, Croatia. These measurements are analyzed for a period from April 2010 until June 2011. This rather long period allows for making quite robust and reliable conclusions. The focus is on mean Bora velocity, turbulence intensity, Reynolds shear stress and turbulence length scale profiles, as well as on Bora velocity power spectra and thermal stratification. The results are compared with commonly used empirical laws and recommendations provided in the ESDU 85020 wind engineering standard to question its applicability to Bora. The obtained results report some interesting findings. In particular, the empirical power- and logarithmic laws proved to fit mean Bora velocity profiles well. With decreasing Bora velocity there is an increase in the power-law exponent and aerodynamic surface roughness length, and simultaneously a decrease in friction velocity. This indicates an urban-like velocity profile for smaller wind velocities and a rural-like velocity profile for larger wind velocities. Bora proved to be near-neutral thermally stratified. Turbulence intensity and lateral component of turbulence length scales agree well with ESDU 85020 for this particular terrain type. Longitudinal and vertical turbulence length scales, Reynolds shear stress and velocity power spectra differ considerably from ESDU 85020. This may have significant implications on calculations of Bora wind loads on structures.

• 대한건축학회논문집:계획계
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• 제35권7호
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• pp.119-126
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• 2019

The active living of the elderly leads to improve their lives and enhance social networks. In the view of the active living, the walkability is an essential factor for the elderly's daily life. To support the active living, making age-friendly environment is important. Considering that the elderly mainly carry out activities through walking, making the age-friendly walking environment is a preliminary action. The existing studies applied various methods such as surveys by experts. In spite of the benefits in theirs, there is still a limitation that current walkability measurement methods did not incorporate the actual elderly's walking activity. Thus, the purposes of this study is to measure the elderly's walking quantitatively using a wearable sensor, and to investigate the feasibility of comparing several walking environments based on the data collected from the actual elderly's walking. To do this, experiment was conducted in four types environments with 22 senior subjects. The walkability was measured by walking stability represented quantitatively as Maximum Lyapunov Exponent (MaxLE). Through the experiment results, it was confirmed that the stability of the elderly walking was different according to the walking environment, which also meant that bodily responses (walking stability) is highly related to walkability. The results will provide an opportunity for the continuous diagnosis of walking environments, thereby enhancing the active living of the elderly.

• 한국식품과학회지
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• 제38권6호
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• pp.838-842
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• 2006

Guar 검, xanthan 검, pullulan을 첨가하여 증편을 제조하여 $4^{\circ}C$에서 저장한 시료의 수분함량의 변화는 유의차가 없었다. 검의 첨가 농도를 낮게 하여 증편을 제조한 경우에는 검 첨가증편의 경도가 무첨가군에 비해 감소하였으나 검의 첨가농도가 0.5% 이상을 첨가하게 되면 pullulan을 제외하고 경도가 무첨가군보다 높게 나타났다. 검류 첨가에 의해 증편의 노화 유형은 변화했으며, Avrami 지수는 pullulan과 xanthan검을 첨가한 경우에는 n=1에 가까운 값을 나타내어, xanthan 검과 pullulan의 노화 유형이 유사하게 나타났다. Pullulan의 첨가량이 증가함에 따라 시간상수(1/k)도 5.37에서 15.65로 증가하는 것으로 나타났다. 이와 같은 실험결과에 의해 검류 첨가량에 따라 수분함량 변화가 거의 발생하지 않으며, 경도 변화도 적게 나타났다. Xanthan 검 또는 pullulan 첨가가 증편의 노화 속도를 늦춰줌으로써 노화가 지연되며 shelf-life 연장에 효과가 있는 것으로 나타났으며, xanthan 검 또는 pullulan보다 guar 검 첨가한 경우가 가장 효과가 적음을 알 수 있었다.

• 생명과학회지
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• 제17권7호통권87호
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• pp.937-943
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• 2007

2005년 5월부터 2006년 3월까지 6회에 걸쳐 안동호에 서식하는 주요어종의 어류상과 길이-무게 상관관계를 조사한 결과는 다음과 같다. 본 조사에서 확인된 어류는 총 7과 20종2540개체였으며, 우점종은 누치 (Hemibarbus labeo, 19.6%), 아우점종은 떡붕어(Carassius cuvieri, 19.2%)로 나타났다. 한국고유종은 치리(Hemiculter eigenmanni, 7.1%), 참몰개(Squalidus chankaensis tsuchigae, 0.1%), 꺽지 (Coreoperca herzi, 0.1%) 등 3종, 외래어종은 떡붕어(Carassius cuvieri, 19.21%), 블루길(Lepomis macrochirus,4.2%), 베스(Micropterus salmoides, 0.2%)3종으로 나타났으며, 우점도는 0.388, 종다양도 3.159, 종풍부도 2.423, 균등도는 0.730이었다. 주요 출현어종 9종에 대한길이-무게 상관관계식에서 피라미(Zacco platypus, 3.2509, $R^{2}$= 0.9928)가 가장 높은 성장도를 나타냈으며, 누치(H. labeo, 2.9162, $R^{2}$ = 0.9567)가 가장 낯은 성장도를 나타냈다. 각 어종에 패한 비대지수에서는 누치( H. labeo)와 잉어(Cyprinus carpio)를 제외한 7개 어종에서 기울기가 양의 값으로 나타나 건강상태가 비교적 양호한 것으로 확인되었다. 각 어종에 대한 길이-무게 상관관계에서 매개변수 b의 값의 평균은 3.1079로 성장상태가 매우 양호한 것으로 확인되었다.

• 한국안전학회지
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• 제3권2호
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• pp.35-48
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• 1988

Modern technological progress demands the use of materials at high temperature and high pressure. One of the most critical factors in considering such applications - perhaps the most critical one - is creep behavior. In this study the stress exponents n were determined during creep over the temperature range of $90^{\circ}C\;to\;500^{\circ}C$ (0.4 - 0.85 Tm) and stress range of 0.64 kgt/$mm^2$ in order to investigate the creep hehavior. The stress dependence of rapture time (n') were determined over the temperature range of $200^{\circ}C\;to\;240^{\circ}C$ and stress range of 8.13 kgt/$mm^2$ to 9.55 kgt/$mm^2$ in order to investigate to creep rupture property. And the stress transient dip tests were also carried out for the internal stress ${\sigma}i$ over the temperature range of $90^{\circ}C\;to\;500^{\circ}C$ and stress range of 0.64kgt/$mm^2$ to 17.2 kgt/$mm^2$. The creep tests for constant temperature and stress transient dip tests were conducted in air with Al 7075 alloy under constant tensile load. At around the temperature range $200^[\circ}C\;-\;230^{\circ}C$ and the stress level 8.13 - 9.55 (kgt/$mm^2$), the temperature range $280^{\circ}C\;-\;310^{\circ}C$ and the stress level 1.85 - 2.55 (kgt/$mm^2$), the temperature range $380^{\circ}C\;-\;410^{\circ}C$ and the stress 1.53 - 0.91 (kgt/$mm^2$), the stress exponent in had the value of 6.2 - 6.65 but at around the temperature range $90^{\circ}C\;-\;120^{\circ}C$ and the stress level 10 - 17.2(kgt/$mm^2$), the value of 1.3, and at around the temperature range $470^{\circ}C\;-\;500^{\circ}C$, the stress level 0.62 - 1.02 (kgt/$mm^2$) the value of 1-1. Besides these results, at around the temperature $200^{\circ}C\;-\;240^{\circ}C$ the stress dependence of rupture time (n') had the value of 6.3. Finally, it was found that the value n calculated by considering the applied stress dependence of the internal stress were in good agreement with those obtained for the creep test. Then, it was concluded that the change in n was mainly attributed to the difference of the applied stress dependence of the internal stress and the ratio of the internal stress to the applied stress, and the creep rupture life may be represented as.

• 한국자동차공학회논문집
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• 제13권3호
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• pp.186-192
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• 2005

The apparent activation energy Qc, the applied stress exponent n, and rupture life have been determined from creep test results of AZ31 Mg alloy over the temperature range of 200$^{\circ}C$ to 300$^{\circ}C$ and the stress range of 23.42 MPa to 93.59 MPa, respectively, in order to investigate the creep behavior. Constant load creep tests were carried out in the equipment including automatic temperature controller with data acquisition computer. At the temperature of $200^{\circ}C{\sim}220^{\circ}C$ and under the stress level of 62.43~93.59 MPa, and at around the temperature of $280^{\circ}C{\sim}300^{\circ}C$ and under the stress level of 23.42~39.00 MPa, the creep behavior obeyed a simple power-law relating steady state creep rate to applied stress and the activation energy fur the creep deformation was nearly equal to that of the self diffusion of Mg alloy including aluminum From the above results, at the temperature of $200^{\circ}C{\sim}220^{\circ}C$ the creep deformation for AZ31 Mg alloy seemed to be controlled by dislocation climb but controlled by dislocation glide at $280^{\circ}C{\sim}300^{\circ}C$ .And relationship beween rupture time and stress at around the temperature of $200^{\circ}C{\sim}220^{\circ}C$ and under the stress level of 62.43~93.59 MPa, and again at around the temperature of $280^{\circ}C{\sim}300^{\circ}C$ and under the stress level of 23.42~39.00 MPa, respectively, appeard as fullow; log$\sigma$=-0.18(T+460)(logtr+21)+5.92, log$\sigma$ = -0.25(T+460)(logtr+21)+8.02 Also relationship beween rupture time and steady state creep rate appears as follow; ln$\dot$ =-0.881ntr-2.45

• 한국해안·해양공학회논문집
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• 제27권4호
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• pp.246-257
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• 2015

피해 자료의 부족에 따른 불확실성 뿐만 아니라 시간의 진행에 따른 불확실성을 고려하기 위하여 추계학적 확률과정을 이용하여 시간에 따른 구조물의 피해 경로를 정량적으로 추적하였다. 누적피해도와 내구년수의 분포함수를 시간의 함수로 산정하여 추계학적 확률과정을 적용할 때 주의해야 하는 중요한 특성들을 제시하였다. 특히, 본 연구에서는 추계학적 확률과정을 경사제 피복재에 적용하여 시간에 따른 누적 피해도를 추적할 수 있는 방법을 제안하였다. 확률과정의 매개변수들을 추정하기 위하여 개발된 표본경로기법을 이용하여 경사제 피복재의 시간에 따른 누적 피해도가 포화거동을 따른다는 사실이 확인되었다. 또한 누적 피해도 산정시 중요한 역할을 하는 멱함수의 지수를 정량적으로 산정하여 경사제 피복재의 누적 피해도를 시간에 따라 추적하는 것이 가능했다. 마지막으로 한계수준을 다양하게 변화시키면서 파괴확률의 거동특성을 해석하였다.

• 한국식품영양학회지
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• 제29권6호
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• pp.930-937
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• 2016

This study investigated the quality characteristics, antioxidant activities, and retarding retrogradation of sponge cakes made with 0%, 1%, 3%, 5% and 7% pumpkin (Cucurbita moschata Duch.) leaf powder. Specific capacity significantly increased with the addition (0.33~0.38), but baking loss and dough yield were not significantly different (p<0.05). In color, there was a decrease in the L-value, a-value and b-value, but ${\Delta}E$ increased in proportion to the amount of pumpkin leaf powder. Moisture content increased in the 0~3% additions, from 27.90~31.68%, but decreased in 5% and 7% (22.37% and 28.15%, respectively). pH tended to decrease significantly according to the amount of pumpkin leaf powder (p<0.05). Hardness increased with the addition of pumpkin leaf powder, and pumpkin leaf groups presented higher springiness and cohesiveness than the control. Chewiness was not significantly differ (p<0.05). In retarding retrogradation, Avrami exponent (n) showed that addition of 5% (0.1329) had more retarding retrogradation effect than the control (0.4319), whereas time constant (1/k) showed both 3% (100.00) and 5% (70.42) addition had more effect than control (18.45). Total phenols and flavonoids content increased proportionate to the addition levels. ABTS radical scavenging activity tended to increase according to the level of pumpkin leaf powder. In sensory properties, 5% addition showed maximum color, and 3% addition had the highest scores in flavor, moistness, sweetness, chewiness and overall acceptability. These results suggested that pumpkin leaf was a good addition to improve the quality characteristics, health and sensory preferences. The most appropriate proportion to have the effect of retarding retrogradation in sponge cake is 3%.