• Journal of the Korean Institute of Telematics and Electronics A
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• v.32A no.1
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• pp.14-25
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• 1995

The main contribution of this paper can be summarized in two items as follws. Firstly, a modelling of mobile communication channel with Rayleigh fading characteristics is presented. Actual signal environments can be approximated as being real measurements by a proper mathematical representation of fluctuation of channel parameters due to Doppler effect, that is determined by the relative speed between transmitter and receiver, and noises, that vary at each sampling time. Secondly, an alternative procedure of synthesizing an adaptive equalizers is presented for recovering original signals that have been corrupted through the modelled channel. In order to compute the optimal tap coefficients for a high speed data(512 k symbol/sec) on a real-time basis, the CGM that guarantees fast and stable convergency is adopted during the training period of each frame. The coefficients obtained by the CGM are used as initial values for the LMS algorithm to trace the optimal coefficients during the data period that vary at each sampling time due to the mobility and noise at the receiver. Using the modelling presented in this paper, distributions of received signal power in various signal environments are demonstrated. The performance of the eqalizer proposed in this paper is shown as a function of BER under the various signal circumstances of mobile communications.

• Journal of Korea Society of Industrial Information Systems
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• v.5 no.1
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• pp.31-36
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• 2000

This paper presents a design method of deadbeat controller for DC motor driving a rotational system with gear. The deadbeat-response design developed for control system of a sampled continuous-data process does not guarantee zero intersampling ripples, but the proposed deadbeat control system that consists of the integral controller and the full-order state observer, and zero-order hold using in continuous systems, has many advantages such as an output response without the ripples and reaching the steady state without error after a given sampling period and faster settling time than the optimal control system in the same sampling period. The results of a case study through matlab simulation are shown that the efficiency of the proposed controller for DC motor driving a rotational system with gear is verified by comparing with optimal controller etc.

• Transactions on Control, Automation and Systems Engineering
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• v.2 no.4
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• pp.274-284
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• 2000

In this paper, the design methodology of digital fuzzy controller(DFC) for the systems with time-delay is presented and the qualitative effects of the quantizers in digital implementation of a fuzzy controllers are investigated. We propose the fuzzy feed-back controller whose output is delayed with unit sampling period and period and predicted. the analysis and the design problem considering time-delay become very easy because the proposed controller is syncronized with the sampling time. The stabilization problem of the digital fuzzy system with time-delay is solved by linear matrix inequality(LMI) theory. Furthermore, we analyze the stability of the quantized fuzzy system. Our results prove that when quantization os taken into account, one only has convergence to some small neighborhood about origin. We develop a fuzzy control system for backing up a computer-simulated truck-trailer with the consideration of time-delay and quantization effect. By using the proposed method, we analyze the quantization effect to the system and design a DFC which guarantees the stability of the control system in the presence of time-delay.

• Asia-Pacific Journal of Business
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• v.4 no.2
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• pp.31-40
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• 2013

This paper portrays the perception of buying behaviour, factors of product preferences and product switch-over among women consumers in Vellore district of Tamil Nadu. To conduct this study, 300 respondents from 20 village blocks of Vellore district were selected using stratified random sampling as the technique and descriptive sampling as the design. The study came out with interesting results and conclusions. It was found that more than half of the respondents were purchasing the product without a bill. It was also found that the respondents who repaired their product in the authorized service centre during warranty period did not continue the same after the warranty period and preferred nearby repair shops. It was further found that more than half of the respondents were checking expiry date and quality standards while purchasing a product. The study's scope was limited to women consumers at Vellore district. It could be used for further research in other aspects such as gender comparison in Vellore district and comparison with other districts of Tamil Nadu and other states of India. It was suggested that there is still a necessity to upgrade the standard of the people in many aspects like education, occupation and level of income, which shall help them to compete with the neighboring cities on living standards.

• The Journal of Asian Finance, Economics and Business
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• v.8 no.4
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• pp.151-159
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• 2021

This study aims to compare the level of stability of the Islamic banking system in the ASEAN region, particularly in Indonesia, Malaysia and Brunei Darussalam in the face of macroeconomic turmoil. The data used in this study is secondary data obtained from the official website of the government and banks of each country, with sampling using purposive sampling technique during the period 2013 to 2019. The data analysis method used is panel data using Eviews software. The results showed that the average Z-score value of Islamic banking during the study period in each country was Indonesia (15.61), Malaysia (15.56) and Brunei Darussalam (19.10). The GDP (X1) has a positive effect on the stability of Islamic banking by 54.29%, inflation (X2) has a negative effect of -12.24% on the stability of Islamic banking, and the exchange rate (X3) has a positive effect on the stability of Islamic banking by 42.58%. The findings of this study indicate that the three countries have an average Z-score value that is higher than 2.99, so this shows that Islamic banking in several ASEAN countries is in a stable condition. In addition, a higher GDP and a stronger exchange rate can also encourage a more stable Islamic banking.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.56 no.6
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• pp.899-908
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• 2023

Droughts can alter the dynamics of aquatic ecosystems, including fish communities. This study compared the variations in fish communities in Juam reservoir before and after drought events. Fish sampling was conducted five times from April 2021 to April 2023 using three different sampling methods (kick net, cast net, and gill net). The water level in the reservoir reached its peak (103.73 EL.m, 62.2% capacity) in September 2021, before the drought, and dropped to its lowest point (88.84 EL.m, 17.6% capacity) in April 2023. The dissolved oxygen content in the reservoir decreased from 27 to 6.3 mg/L between the period with the lowest water level (April 2023) and the period with the highest water level (September 2021). In September 2021, 466 fish were collected, but after one year of drought, the number of individuals decreased to 105. Further, the number of fish collected and water levels were positively correlated. Dominant species exhibited a population decline of over 60% with decreasing water levels. These findings highlight the importance of fishery resource management during drought periods.

• The Research Journal of the Costume Culture
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• v.11 no.2
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• pp.253-262
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• 2003

The purposes of the study were (1) to analysis Korean traditional wedding costumes through families's wedding photographs from 1940 to 2000, and (2) to categorize bride and groom's costumes according to the wedding time by means of a time series analysis. (3) to find out functional relationship among changes in garment types, garment details, embellishments and colors. The study was a documentary research and data were collected from 390 family wedding photographs by a convenient sampling. The data were analyzed by qualitative and quantitative method and the statistic used were frequency, content analysis, and cross-tab analysis. The results were as follows; First, the garments of wedding couples were categorized into 5 period according to garment's characteristics. 1. The period between 1940～1959 : Korean traditional wedding costumes and western style wedding costumes were existed together in Korean wedding culture. 2. The period between 1960～early 1970's western wedding costumes were dominated. 3. The period of late 1970's : wedding couple's costumes became more formal and decorative. 4. The period of 1980's : introducing see-through materials for brides and tuxedo suit for grooms. 5. The period of 1990's : extravagance in shapes and exposure. Second, there were significant relationships among brides's dress types and neckline, glove length, embellishments and transparency of materials and among groom's garment types and necktie types, types and color of shirts, vests. Third, the time series analysis of bride and groom's outfit produced 5 schematic expressions of wedding outfits according to the period.

• Journal of Korean Society for Atmospheric Environment
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• v.14 no.2
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• pp.117-132
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• 1998

The main purposes of this study are to investigate the distributional characteristics of polycyclic aromatic hydrocarbons (PAH) in the vapor and particulate phases in the ambient atmosphere, and to evaluate the effect of ambient temperature on the vapor-particle partitioning during the sampling period. A total of 64 samples were collected during a period of 1995 to 1996, using a medium-volume sampler with XAD-2 adsorbents and quartz fiber filters. Analyses of PAH were carried out using HPLC with UV and Fluorescence detections. In this study, a significant seasonal variation in the distributions was observed, reflecting the effect of ambient temperature on the vapor-particle partitioning of PAH. The relationship between the vapor-particle distributions of the 3 to 5 rings PAH and ambient temperature is considered to be well described using the Langmuir adsorption concept. The estimated empirical constants for each PAH in the relationship, particularly for the more volatile compounds, were also comparable with results from other studies. However, it is still difficult to accurately estimate the initial vapor-particle distribution of PAH in the ambient air, since it is not known to what extent the trapped vapours originated from the particles laden in the filter by being volatilized or from the air samples initially present in the vapour phase. The distribution factors for volatile PAH with 3 to 4 rings appeared to be comparable with those in the literature. It should be noted, however, that these distribution factors give information only about the distribution of PAH between the two phases under a specific sampling condition, and hence may provide only semi -quantitative information on the vapor-particle distributions in the atmosphere.

• Journal of Navigation and Port Research
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• v.38 no.2
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• pp.147-154
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• 2014

The purpose of this study was to identify the correlation among participating in the extreme sports, the flow experience and the satisfaction of life. 420 participants of the extreme sports were selected by the Judgement Sampling Method. Factor analysis and multi-regression analysis have been conducted. The conclusion is as follows. First, the participants' life satisfaction is partially affected by the duration period and term. Second, period, frequency, duration partially effect to life satisfaction. Third, flow experience partially effect to life satisfaction.

• Korean Journal of Environmental Agriculture
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• v.24 no.1
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• pp.17-23
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• 2005

In order to examine effects of sampling frequency during rainfall-runoff process from paddy field on the estimation of pollution load, EMCs of several water sampling frequencies were examined. Water quality samples were conducted by every two hours interval for each event. It was found that difference of load estimation between five times sampling and two hours consecutive sampling during rainfall-runoff showed $15.2{\sim}-15.2%$ for T-N, $20.0{\sim}-26.2%$ for T-P, $28.6{\sim}-35.7%$ for the SS, respectively. In the same way, the effects of number of sampling data on estimation of pollution load using runoff-mass load(L-Q) method were investigated. L-Q equation made of five times sampling data provided 10% differences in estimation of mass loads of T-N, T-P, and SS when compared to those by L-Q equation using entire two hours consecutive sampling data during runoff process.