• 한국농공학회지
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• 제37권5호
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• pp.73-80
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• 1995

The uses of stage-storage curve function are diverse in irrigation reservoirs. The curve functions would be used to determine the optimal size of spillway length and the inundation area above full water level based on the flood routing in reservoirs. In addition, the curve function would he used to transform the stage to the storage for the reservoir water management, in which the storage is the supply water. Besides those, the curve is necessary for the planning of dredging, the estimation of the effective and the dead storage, the drought management by reservoir, etc. The curve function data, however, are almost unavailable for these purposes. According to the statistics, about 74% of the 2, 900 resevoirs which are maintained by Farm Land Improvement Association have no more effective data. Therefore, the simulation of the curve function could be better alternative. The curve functions were simulated derivating the regression equations based on the basin relief ratio and the effective depth. The results of the verification show the enough reliability of the application to generate the curve function in some reservoirs which do not have the surveyed stage-storage data. Also, even though the averaged curve function would be applicated without the basin relief ratio data, the result shows that the simulated curve is closer to the real one than the linear function by only the existing effective storage data.

• 한국공작기계학회논문집
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• 제12권4호
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• pp.63-69
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• 2003

In discontinuous composite mechanics, shear lag theory is one of the most popular model because of its simplicity and accuracy. However, it does not provide sufficiently accurate strengthening predictions in elastic regime then the fiber aspect ratio is small. This is due to its neglect of stress transfer across the fiber ends and the stress concentrations that exist in the matrix regions near the fiber ends. To overcome this shortcoming, a more simplified shear lag model introducing the stress concentration factor which is a function of several variables, such as the modulus ratio, the fiber volume fraction, the fiber aspect ratio, is proposed. It is found that the modulus ratio($E_f$/$E_m$) is the essential variable among them. Thus, the stress concentration factor is expressed as a function of modulus ratio in the derivation. It is found that the proposed model gives a good agreement with finite element results and has the capability to correctly predict the values of interfacial shear stresses and local stress variations in the small fiber aspect ratio regime.

• 대한한방내과학회지
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• 제29권3호
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• pp.621-628
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• 2008

Objectives : The aim of this study was to investigate changes of gastric vagal nerve activity and pyloric valve function after execution of combination treatments of both electroacupuncture at Zusanli(ST36) and manual acupuncture at other acupoints in patient with functional dyspepsia. Methods : Bowel sounds of 49 patients (18 male, 31 female) were recorded and their % of bowel sound (%BS) and ratio of dominant frequency (DF) were analyzed. Postprandial %BS was used to indicate the gastric vagal activity after eating. Ratio of postprandial/fasting dominant frequency was used to present the degree of pyloric valve function. According to values of %BS and DF ratio, each patient was classified into normal or abnormal (<6 %BS, hypoactivity: <1 DF ratio, dysfunction) group. For 2 weeks, patients received a treatment consisting of both electroacupuncture stimulation at Zusanli (ST36) and acupuncture at other meridian points. Variation of parameters shifting normal to abnormal or abnormal to normal was observed, and total cure rate was calculated. Results : Total cure rate of %BS was 16%, and that of DF was 37%. Patients who improved to normal value from abnormal or aggravated to abnormal level showed both significant difference in both vagal nerve hypoactivity and pyloric valve dysfunction, respectively. Conclusions : Analysis of bowel sound might be useful to evaluate both gastric vagal nerve activity and pyloric valve function. Combination effects of Zusanli (ST36) electroacupuncture and manual acupuncture of other acupoints showed a bidirectional effect in which their activity and function were in general improved. sometimes from aggravated to abnormal level.

• 한국세라믹학회지
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• 제36권2호
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• pp.122-129
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• 1999

알루미나 분말/(알루미나+결합체+가소제)의 비(X)와 결합체/(결합체+가소제)의 비(Y)를 각각 변화시켜 제조한 알루미나 그린 테이프의 complex modulus를 Micro Fourier Rheometer를 이용하여 측정하였다. X와 Y의 증가에 따라 Transfer function(TF) magnitude는 증가하고 Transfer function(TF) phase는 감소하는 경향을 보였으며 이로부터 X비와 Y비의 증가가 테이프의 탄성을 증가시켜는 요인임을 알 수 있었다. 온도가 증가함에 따라 알루미나 테이프의 TF magnitude는 작아지고 TF phase는 커지는 것으로부터 테이프의 점성이 증가함을 알 수 있었다. 특히 Y비에 따른 complex modulus의 변화는 유리전이온도와 관련이 있으며 변화값은 측정 조성 범위 내에서 X비에 의한 변화값보다 큼을 볼 수 있었다. complex modulus 측정을 통하여 알루미나 테이프의 성형이 가능하기 위해서는 TF phase 값이 17$^{\circ}$이상이어야 함을 유추할 수 있었다.

• 천문학회보
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• 제38권1호
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• pp.37.2-37.2
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• 2013

We present the galaxy luminosity function (LF) of the Abell 119 cluster. Deep images in u, g, r bands were taken using MOSAIC 2 CCD on a Blanco 4-m telescope at CTIO. Based on scaling relations at faint magnitudes and spectroscopy at bright magnitudes, accurate membership of galaxies is determined. The LF is fitted by a single Schechter function and a two components (Gauss + Schechter) function. Blue galaxies are well fitted by a single Schechter function with steep slope ${\alpha}$ ~ -1.55). Red galaxies in the inner, high density region are fitted by single Schechter function with shallow slope (${\alpha}$ ~ -1.30), while red galaxies in the outer, low density region are well fitted by a two components function. The different slope of LFs between the inner and outer seems to stem from the luminosity segregation of A119 indicating larger number ratio of luminous to faint ratio towards the cluster center. The different shape of LFs seems to be resulted from the different composition of luminous and faint galaxies among main-cluster, sub-cluster, and infall region.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제5권1호
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• pp.141-156
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• 2011

In this paper we develop a link cost function for data delivery in sensor network. Usually most conventional methods determine the optimal coefficients in the cost function without considering the surrounding environment of the node such as the wireless propagation environment or the topological environment. Due to this reason, there are limitations to improve the quality of data delivery such as data delivery ratio and delay of data delivery. To solve this problem, we derive a new cost function using the concept of Partially Connected Neural Network (PCNN) which is modeled according to the input types whether inputs are correlated or uncorrelated. The correlated inputs are connected to the hidden layer of the PCNN in a coupled fashion but the uncoupled inputs are in an uncoupled fashion. We also propose the training technique for finding an optimal weight vector in the link cost function. The link cost function is trained to the direction that the packet transmission success ratio of each node maximizes. In the experimental section, we show that our method outperforms other conventional methods in terms of the quality of data delivery and the energy efficiency.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제14권1호
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• pp.40-52
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• 2020

In this paper, we consider a precoder design problem for multiuser interference channel. Most of the conventional schemes for precoder design utilize a signal-to-interference-plus-noise ratio (SINR) as a cost function. However, since the SINR metric of a desired transmitter-receiver pair is a function of precoding vectors of all transmitters in the multiuser interference channel, an analytic closed-form solution is not available for the precoding vector of a desired transmitter that maximizes the SINR metric. To eliminate coupling between the precoding vectors of all transmitters and to find a closed-form solution for the precoding vector of the desired transmitter, we use a signal-to-leakage-plus-noise ratio (SLNR) instead as a cost function because the SLNR at a transmitter is a function of the precoding vector of the desired transmitter only. In addition, channel estimation errors for undesired links are considered when designing the precoding vector because they are inevitable in a multiuser interference channel. In this case, we propose a design scheme for the precoding vector that is robust to the channel estimation error. In the proposed scheme, the precoding vector is designed to maximize the worst-case SLNR. Through computer simulation, we show that the proposed scheme has better performance than the conventional scheme in terms of SLNR, SINR, and sum rate of all users.

• 한국추진공학회지
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• 제15권4호
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• pp.35-40
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• 2011

희박 예혼합 가스터빈에서 발생되는 연소 불안정 현상의 메커니즘을 규명하기 위하여 입구 속도 변동에 대한 열발생 변동을 정량화한 화염 전달 함수가 실험적으로 규현되었다. 이를 위하여 실제 가스터빈과 유사한 형태를 갖는 모형 연소기가 제작되었으며, 열발생율의 측정을 위한 가시화 연소기가 장착되었다. 또한 흡기 속도의 변조를 위하여 가변 속도 모터 및 유량 제어 장치가 설계되었고, 이러한 장치들을 통하여 입구 속도 변동이 열발생율의 진폭에 미치는 영향 및 화염 구조의 변화를 실험적으로 계측하였다. 실험 결과 화염 전달 함수는 당량비와 같은 운전 조건과 더불어 속도 섭동 조건에 대하여도 크게 의존하며, 화염의 길이와 섭동파 파장의 비율을 의미하는 Strouhal 수에 의하여 일반화될 수 있었다.

• 한국공간구조학회논문집
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• 제18권1호
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• pp.77-84
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• 2018

The identification of damping ratios in buildings is a well-known problem and appears to be of important and crucial interest in the safety and serviceability design. When compared to an estimation of the stiffness, i.e. natural frequency, and mass, the damping ratio is the most difficult quantity to determine. Many previous studies have examined the characteristics of damping ratios from ambient vibration, but the measurement time is roughly within 2 hours. In this paper, characteristics of damping ratios and natural frequencies of 4 story RC building were investigated using long-term ambient vibration. Free vibrations were obtained using random decrement technique, and damping ratios were evaluated by the envelop function, continuous wavelet transform, and logarithmic decrement. It was found that although the natural frequencies show little variations with time, the damping ratios show some variations with time and the largest variations found in the damping ratios obtained from the continuous wavelet transform. The damping ratios from the envelop function showed the smallest mean and standard deviation. And the probability distribution of damping ratios seems to follow the logarithmic normal distribution.

• 상하수도학회지
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• 제19권5호
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• pp.619-624
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• 2005

This work is for examining a simplified equation based on the rational formula, which can easily decide storm-water detention volume in small urban catchments. The storm-water detention volume is determined by the inflow hydrograph flowing to detention basin and the outflow hydrograph discharged from the detention basin. The ratio of average outflow over the period of rainfall duration against allowable discharge was 0.5 in former simplified equation. But this research has found that the average outflow ratio depends on the storage methodology. In the case of the on-line storage method, the average outflow ratio is a function of the time of concentration of the catchments and rainfall duration, which ranged from 0.5~1.0. In the case of the off-line storage method, the average ratio is a function of peak discharge and allowable discharge except above time of concentration and rainfall duration, where its function value ranged from 1.0~2.0. When applying this equation to small catchment in Mokpo city, South Korea, we could easily calculate the relation curve between the storm-water detention volume and allowable discharge.