• 상하수도학회지
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• 제25권5호
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• pp.651-658
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• 2011

Nitrate is a common contaminant in industrial wastewater and ground water. The maximum contaminant level set by EPA for nitrate of 10 mg/L as N. In this study, nitrate was removed using bipolar ZVI packed bed electrolytic cell that maximized the contact area between each electrode and contaminants under 600 V. Also this study investigates the simultaneously deals with removal of ammonia by operating air stripping tower. In addition to the air stripping also helped to precipitate iron ions to the form of iron oxides. Bipolar ZVI packed bed electrolytic cell was also effective in removing coliform by electrical power. In the continuous experiments for the simulated wastewater (initial nitrate for 25 mg/L as N), maximum 96.3% removal of nitrate was achieved in the applied 600 V at the flow rate of 6 mL/min.

• 한국정보통신학회논문지
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• 제9권1호
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• pp.8-15
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• 2005

비선형적인 위상 변화를 지닌 비정상(non-stationary)신호는 레이더, 통신, 지질탐사, 음향, 생체공학 응용등 여러 분야에서 쉽게 접하는 신호이다. 비정상 신호는 일반적으로 시간의 변환에 따라 신호의 스페트럼 특성이 변화하는 신호를 의미하며, 순간 주파수는 신호의 특정시간에 해당하는 신호성분의 주파수를 의미한다. 따라서 열거한 레이더, 음향, 생ㅊ신호등에 있어서 순간 주파수는 신호의 물리적 특성을 파악하기 위한 중요한 변수이다. 이 논문에서는 연속 웨이브렛 변환을 이용한 비정상 신호의 순간 주파수를 결정에 대하여 연구하였고, 기존의 방법과 비교하였다. 신호에 잡음이나 여러 가지의 주파수가 중첩되어 있는 경우, 기존에 방법들로서는 정확한 순간 주파수를 결정할 수 없는 반면, 웨이브렛 변환을 이용한 경우, 신호의 성분에 관계없이 상당히 정확한 순간주파수를 결정할 수 있음에 대하여 설명하였다.

• 한국정밀공학회지
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• 제33권3호
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• pp.217-223
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• 2016

In this paper, the movement of a liquid metal droplet in a channel by continuous electrowetting effect is analyzed. The channel is fabricated using two glass substrates and silicone rubber as spacers, and a mercury droplet and dilute sulfuric acid are added into the channel. The droplet is moved according to voltage applied at both ends of the channel through an electrolyte. According to the shape of the droplet and the applied voltage, the velocity of the droplet is changed. The velocity is proportional to the applied voltage and inversely proportional to the length of the droplet, both theoretically and experimentally. Contact angle hysteresis and a meniscus change were also found in the moving state. This implies the existence of a threshold in movement by Laplace pressure difference. The experiment indicated that the sliding angle was inversely proportional to the width of the droplet but that the voltage threshold was proportional to the width.

• 한국정보시스템학회지:정보시스템연구
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• 제31권1호
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• pp.91-113
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• 2022

Purpose In the era of the 4th industrial revolution, the introduction of unmanned stores is rapidly spreading throughout the entire distribution market. Unmanned stores are stores where consumers purchase products on their own through machines and not through contact with people. As there are no managers in unmanned stores, Servicescape is expected to have many effects on the purchasing behavior of consumers. Therefore, this study aims to observe the effect of Servicescape on consumer behavioral intentions. Design/methodology/approach This study wanted to look at the relationships among Servicescape in unmanned stores, utilitarian values, hedonic values, satisfaction, and continuous use intentions. The collected(n=211) from individuals who have experienced in using unmanned stores was analyzed with SmartPLS2.0 to test proposed hypotheses. Findings The research results are as follows. First, it was shown that the space, convenience, and comfortableness of Servicescape have positive effects on utilitarian value, and cleanliness did not have significant effects on utilitarian value. Second, it was shown that space and comfortableness had positive effects on hedonic value, and convenience and cleanliness did not have significant effects on hedonic value. Lastly, it was shown that utilitarian values and hedonic values have positive effects on satisfaction, and satisfaction was found to have positive effects on continuous use intentions.

• Membrane and Water Treatment
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• 제13권5호
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• pp.209-217
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• 2022

In the present research, Ficus religiosa Bark (FRB) is used as an adsorbent for the removal of heavy metal Cr (VI) ions. This Ficus religiosa Bark was characterized by Scanning Electron Microscope, Fourier transform infrared Spectroscopy, Thermo Gravimetric Analyzer and the results showed that activated adsorbent have high adsorption capacity and withstand even in high temperature. Batch and Continuous experiments were conducted to determine the effect of various parameters such as pH, contact time, adsorbent dose and initial metal concentration. The biosorption followed pseudo first order kinetic model. The adsorption isotherms of Cr (VI) on Ficus religiosa fitted well with the Temkin model. In Batch study, maximum biosorption capacity of Cr (VI) was found to be 37.97 mg g^-1 (at optimal pH of 2, adsorbent dosage of 0.3 grams and concentration of Cr (VI) is100 mg L^-1). The Continuous mode of study shows that 97% of Cr (VI) ion removal at a flow rate of 15 ml min^-1. From the results, selected Ficus religiosa Bark has the higher adsorption capacity for the removal of Cr (VI) ions from wastewater.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제16권4호
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• pp.1209-1223
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• 2022

Blood pressure is one of the key physiological parameters for determining human health, and can prove whether human cardiovascular function is healthy or not. In general, what we call blood pressure refers to arterial blood pressure. Blood pressure fluctuates greatly and, due to the influence of various factors, even varies with each heartbeat. Therefore, achievement of continuous blood pressure measurement is particularly important for more accurate diagnosis. It is difficult to achieve long-term continuous blood pressure monitoring with traditional measurement methods due to the continuous wear of measuring instruments. On the other hand, radar technology is not easily affected by environmental factors and is capable of strong penetration. In this study, by using machine learning, tried to develop a linear blood pressure prediction model using data from a public database. The radar sensor evaluates the measured object, obtains the pulse waveform data, calculates the pulse transmission time, and obtains the blood pressure data through linear model regression analysis. Confirm its availability to facilitate follow-up research, such as integrating other sensors, collecting temperature, heartbeat, respiratory pulse and other data, and seeking medical treatment in time in case of abnormalities.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2004년도 추계학술대회 논문집
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• pp.800-805
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• 2004

In this paper, a numerical method for train/track/structure interaction analysis in frequency domain is developed. Track is modelled as continuous beams supported by elastomers. The motion of train is expressed by those of car body, bogies and unsprung masses supported by springs and dampers. The equation of motion for train and track interaction system is derived by applying compatibility condition at the contact points between wheels and rails. The Effects of rail pad stiffness on the behaviors of train and track are analyzed using the presented method.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2002년도 추계학술대회 논문집(II)
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• pp.1094-1099
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• 2002

In this paper, a numerical method for vehicle-track interaction analysis is developed to evaluate vertical dynamic force subjected to rail surface. A vehicle is modelled by lumped masses system and track by multi layered continuous beam system. The equation of motion of vehicle and track interaction system is derived by considering compatibility condition at the contact points between wheel and rail. The input vibration source is given by the empirical formula of power spectral density of track irregularity, which is suggested by FRA. Using this method, dynamic impact factors with the train speed are evaluated.

• 한국지진공학회:학술대회논문집
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• 한국지진공학회 1999년도 추계 학술발표회 논문집 Proceedings of EESK Conference-Fall
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• pp.313-318
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• 1999

The seismic performance of multi-span bridge without seismic detailing is found to be insufficient in longitudinal direction. Shear keys and stoppers can be introduced as an alternative to enhance seismic capacity. The capacity curve of bridge with shear keys is obtained considering two extreme contact conditions of shear keys. Its curve is converted into ADRS spectra and compared with demand spectra. It is concluded that seismic performance can be improved effectively by shear keys and its performance can be evaluated graphically on the ADRS specta.

• 한국철도학회:학술대회논문집
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• 한국철도학회 1999년도 추계학술대회 논문집
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• pp.463-470
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• 1999

In this paper, a numerical method for evaluating the efficiency of vibration reduction of substructure under slab track is developed for optimal design of floating slab track. The equation of motion for train and track interaction system is derived by applying compatibility condition at the contact points between wheels and rails. The train is modelled by 3-masses system and the track by continuous support beam system. Numerical analyses are carried out to investigate the effect of train speed, stiffness and damping of slab-pad, and track irregularity upon vibration reduction in substructure under the track.