• 한국정보통신학회:학술대회논문집
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• 한국해양정보통신학회 2002년도 춘계종합학술대회
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• pp.509-513
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• 2002

This paper presents a semi-blind Minimum Mean Square Error (MMSE) beamforming adaptive algorithm used far OFDM/CDMA combined system. The proposed algorithm exploits the transmitting pilot signal in the initial period of the transmission to update the weight vector. Then it applies the blind adaptive period to update the weight vector, in which the pilot signal is no longer used. The derivation of the algorithm based on the Mean Square Error (MSE) criterion is also presented. Computer simulation is carried out to verify the performance of the proposed approach.

• 국제지역연구
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• 제20권3호
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• pp.123-144
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• 2016

This paper investigates the linkages between returns both in foreign exchange and stock markets, and uncertainties in two markets using daily data for the period of 16 July 2004 to 30 June 2014 in Nepalese economy. Four hypotheses are tested about how uncertainty influences the stock index and exchange rates. From the empirical results, a bivariate EGARCH-M model is the best to explain the volatility in the two markets. There is a negative relationship from the exchange rates return to stock price return. Empirical results do provide strong empirical confirmation that negative effect of stock index uncertainty and positive effect of exchange rates uncertainty on average stock index. GARCH-in-mean variables in AR modeling are significant and shows that there is positive effect of exchange rates uncertainty and negative effect of stock index uncertainty on average exchange rates. Stock index shocks have longer lived effects on uncertainty in the stock market than exchange rates shock have on uncertainly in the foreign exchange market. The effect of the last period's shock, volatility is more sensitive to its own lagged values.

• 분석과학
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• 제36권4호
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• pp.191-197
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• 2023

Radioactivity concentrations for natural radionuclides were determined from fine dust samples collected in Jeju, Korea according to atmospheric events (Asian dust, haze, fog-mist, and non-event), and radium equivalent activity was calculated. The mean atmospheric radioactivity concentrations for ²³⁸U, ²³²Th, and ⁴⁰K in 127 fine dust samples were 0.49, 0.24, and 7.23 µBq m^-3, respectively, and the radium equivalent activity was 33.25 Bq kg^-1. The mean concentrations of ²³⁸U and ²³²Th in the fine dust during the Asian dust period were 1.31 and 1.60 µBq m^-3, respectively, above the global average, while the values for the other three atmospheric events were lower. The ratio of ²³²Th/²³⁸U radioactivity during the Asian dust period was 1.22, higher than the ratio for the other three atmospheric events.

• 환경영향평가
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• 제15권3호
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• pp.207-215
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• 2006

The purpose of this paper is to analyze the spatial distribution and change of the frequency of Yellow Sand days and to examine their relationship with atmospheric circular characteristics at the surroundings of the Korean peninsula. Yellow Sand days data are used by intensity, Siberian High Index and monthly mean temperature of the Northern Hemisphere. In the Middle-western region, the occurrence frequency of Yellow Sand days was higher during the study period (1973-2004). Also, the occurrence frequency of Yellow Sand days increased to latter half 16 years compared with the first half 16 years, and be clearer in Middlewest regions. Yellow Sand days frequency increased, and the trend was distinct in the Jungbu region during the study period. Increasing trend of Yellow Sand days frequency was significant for the recent 22 years. Yellow Sand days had a negative relationship with Siberian High Index in February and March. Therefore, Siberian High Index became weaker in the spring, and possibility for the occurrence of Yellow Sand days was generating larger. Yellow Sand days had a positive relationship in monthly mean temperature of the Northern Hemisphere. Especially, the case of the strong Yellow Sand days is significant. Recently, global warming might be affecting the occurrence of strong Yellow Sand days.

• Journal of Korean Society for Atmospheric Environment
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• 제21권E1호
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• pp.1-11
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• 2005

The concentration levels of gaseous elemental mercury (GEM) in ambient air have been investigated from a monitoring station located in Yang Jae district of Seoul, Korea for a long-term period covering 1997 through 2002. The mean concentration of Hg, if computed based on its hourly measurement data for this six-year period, was $5.32\pm3.53 ng m^{-3} (N = 27,170)$. The inspection of the diurnal distribution patterns indicated the presence of notably high concentration levels during nighttime relative to daytime (e.g., the mean hourly value as high as $9 ng m^{-3}$ in winter nighttime). When divided seasonally, the highest mean of $6.12 ng m^{-3}$ was also observed during winter followed by spring, fall, and summer. The results of our analysis confirmed the relative dominance of winter (seasonally) or nighttime (diurnally), while exhibiting a complicated trend on a long-term basis. Examination of our data over a different temporal scale consistently indicated that dynamic changes in Hg concentrations occurred through time in line with changes in the strength and diversity of the source processes. It is thus acknowledged that the presence of unusually high Hg levels is the consequence of intense man-made activities, while such signatures can vary in a competitive manner.

• 한국생활과학회지
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• 제17권6호
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• pp.1151-1165
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• 2008

This study examined the current status of consumer competency such as consumer knowledge, consumer role attitude, and consumer skill and the related factors among female marriage immigrants. The data were collected from 220 female marriage immigrants living in Yeungnam region. The results of this study were as follows. First, the mean for consumer knowledge was 5.555, the mean for consumer role attitude was 4.067, and the mean for consumer skill was 3.841. Second, the results of t-tests and ANOVA showed that there were differences in the category of consumer knowledge according to age, educational level, marriage duration period, and Internet contact frequency. And the differences were found in age, educational level. communication with family about consumption and TV contact frequency for consumer role attitude, whereas in age, educational level, marriage duration period, employment status, communication with family about consumption and communication with friends about consumption for consumer skill. Third, according to the regression analyses, educational level was significant for consumer knowledge. Additionally, communication with family about consumption and TV contact frequency were significant for consumer role attitude, and age, educational level, communication with family about consumption and communication with friends about consumption were significant for consumer skill.

• 한국항해항만학회지
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• 제36권9호
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• pp.729-735
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• 2012

The primary wave energy conversion by a three-dimensional bottom-mounted oscillating water column (OWC) wave power device in regular waves has been studied. The linear potential boundary value problem has been solved following the boundary matching method. The optimum shape parameters such as the chamber length and the depth of the front skirt of the OWC chamber obtained through two-dimensional numerical tests in the frequency domain have been applied in the design of the present OWC chamber. Time-mean wave power converted by the OWC device and the time-mean second-order wave forces on the OWC chamber structure have been presented for different wave incidence angles in the frequency-domain. It has been shown that the peak period of $P_m$ for the optimum damping parameter coincides with the peak period of the time.mean wave drift force when ${\gamma}=0$.

• 대한족부족관절학회지
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• 제10권2호
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• pp.207-212
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• 2006

Purpose: To evaluate the results of ankle lateral malleolar fractures classified as Danis-Weber type B accompanying osteoporosis that were treated with lag screw. Materials and Methods: 15 cases of Danis-Weber type B ankle lateral malleolar fractures that had T score of less than -2.5 in BMD(bone mineral density) test were selected from June 2003 to December 2005. 10 cases were males and 5 cases were females with mean age of 59 years. The main injury mechanism was supination and external rotation. Mean follow-up period was 16 months. Clinical and radiologic evaluation was done according to Meyer and Kumler's criteria. Results: All cases showed satisfying result and mean radiologic bone union period was 3 months. Anatomic reduction and bone union was acquired in all cases without complications including wound infection, skin necrosis, delayed union and nonunion Conclusions: Lag screw fixation seem to be excellent treatment of Danis-Weber type B lateral malleolar fractures with osteoporosis as it can minimize soft tissue injury and enable anatomic reduction with firm fixation.

• 대한원격탐사학회:학술대회논문집
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• 대한원격탐사학회 2007년도 Proceedings of ISRS 2007
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• pp.57-60
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• 2007

Monthly mean data of ${\AA}ngstr{\ddot{o}}m$ exponent and Aerosol optical thickness (AOT) from Sea-viewing Wide Field-of-view Sensor (SeaWiFS) measurements over the East Asian waters were analyzed. Increasing trend of the satellite-derived ${\AA}ngstr{\ddot{o}}m$ exponent from 1998 to 2004 was found while AOT mean was observed stable during the same period. The trend of ${\AA}ngstr{\ddot{o}}m$ exponent is then interpreted as increase in fraction of small aerosol particles to give quantitative estimates on the variability of aerosols. The mean increase is evaluated to be $4{\sim}5%$ over the 7-year period in terms of the contribution of small particles to the total AOT, or sub-micron fraction (SMF). Possibilities of the observed trend arising from the sensor calibration or algorithm performance are carefully checked, which confirm our belief that this observed trend is rather a real fact than an artifact due to data processing. Another time series of SMF data (2000-2005) estimated from the fine-mode fraction (FMF) of Moderate Resolution Imaging Spectroradiometer (MODIS) supports this observation yet with different calibration system and retrieval algorithms.

• 한국동물학회지
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• 제32권4호
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• pp.329-338
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• 1989

Present study examined the effect of intermittent versus continuous infusion of progesterone(P) on LHRH release in uiuo from the mediobasal hvpothalamus of ovariectomiEed, estradiol-primed adult rats bearing push-pull cannulae. Three experimental groups were studied: 1) control (perfusion medium only),2) intermittent perfusion of P (10-min on,20-min off, and 3) continuous perfusion of p. p (10 ng/mll was directly infused into the MBH following a 3 hr basal collection. Perfusates were collected at 10 min intents린s on ice and LHRH release was measured by LHRH radioimmunoassav. Cycle detector analysis revealed that the spontaneous HRH output in the control group was pulsatile over a 7 hr push-pull perfusion period. The mean basal LHRH release, pulse amplitude and pl서se period were 0.68 $\pm$ 0.03 ps110 min, 1.15 $\pm$0.08 pg and 60 $\pm$ 9 min, respectivelv. Intermi구eat perfusion of P clearly stimulated the mean LHRH release (pre-P vs post-P: 1.14 $\pm$ 0.18 vs 1.99 $\pm$ 0.53 pg) without changes in LHRH pulse frequency. In contrast to intermittent infusion of p, continuous administration of P faithed to modify LHRH release, since the mean LHRH release and pulse amplitude between pre-P and post-P perfusion urere similar. The in vitro study clearly showed that intermittent, but not continuous administration of P is effective in stimulating LHRH release. Therefore, it appears that rhythmic secretion of P mal be the erective signal for activating the neural LHRH apparatus.