• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2006.05a
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• pp.947-949
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• 2006

In the microcell or picocell-based system the frequent movements of mobiles bring about excessive traffics into the networks. In this paper we study multi-criteria decision making which can increase estimation accuracy by considering other multiple decision parameters than the received signal strength.

• Transactions on Control, Automation and Systems Engineering
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• v.4 no.3
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• pp.224-230
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• 2002

In this paper, a counting algorithm hybridized with an adaptive automatic thresholding method based on Otsu's method and the algorithm that elongates markers obtained by the well-known watershed algorithm is proposed to enhance the exactness of the microcell counting in microscopic images. The proposed counting algorithm can be stated as follows. The transformed full image captured by CCD camera set up at microscope is divided into cropped images of m$\times$n blocks with an appropriate size. The thresholding value of the cropped image is obtained by Otsu's method and the image is transformed into binary image. The microbial cell images below prespecified pixels are regarded as noise and are removed in tile binary image. The smoothing procedure is done by the area opening and the morphological filter. Watershed algorithm and the elongating marker algorithm are applied. By repeating the above stated procedure for m$\times$n blocks, the m$\times$n segmented images are obtained. A superposed image with the size of 640$\times$480 pixels as same as original image is obtained from the m$\times$n segmented block images. By labeling the superposed image, the counting result on the image of microbial cells is achieved. To prove the effectiveness of the proposed mettled in counting the microbial cell on the image, we used Acinetobacter sp., a kind of ammonia-oxidizing bacteria, and compared the proposed method with the global Otsu's method the traditional watershed algorithm based on global thresholding value and human visual method. The result counted by the proposed method shows more approximated result to the human visual counting method than the result counted by any other method.

• Journal of Communications and Networks
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• v.7 no.2
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• pp.157-170
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• 2005

The combination of multiple antennas and multi-carrier code division multiple-access (MC-CDMA) is a strong candidate for the downlink of the next generation mobile communications. The study of such systems in scenarios that model real-life trans-missions is an additional step towards an optimized achievement. We consider a realistic MIMO channel with two or four transmit antennas and up to two receive antennas, and channel state information (CSI) mismatches. Depending on the mobile terminal (MT) class, its number of antennas or complexity allowed, different data-rates are proposed with turbo-coding and asymptotic spectral efficiencies from 1 to 4.5 bit/s/Hz, using three algorithms developed within the European IST-MATRICE project. These algorithms can be classified according to the degree of CSI at base-station (BS): i) Transmit space-frequency prefiltering based on constrained zero-forcing algorithm with complete CSI at BS; ii) transmit beamforming based on spatial correlation matrix estimation from partial CSI at BS; iii) orthogonal space-time block coding based on Alamouti scheme without CSI at BS. All presented schemes require a reasonable complexity at MT, and are compatible with a single-antenna receiver. A choice between these algorithms is proposed in order to significantly improve the performance of MC-CDMA and to cover the different environments considered for the next generation cellular systems. For beyond-3G, we propose prefiltering for indoor and pedestrian microcell environments, beamforming for suburban macrocells including high-speed train, and space-time coding for urban conditions with moderate to high speeds.

• Journal of Convergence Society for SMB
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• v.1 no.1
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• pp.67-73
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• 2011

Handover in high speed mobile communication service, in particulary mobile WiMAX is supported efficiency mobility to 120km/h speed. But, in order to accommodate number of user increment in a cell, wireless network is increment to microcell and picocell by allocate bandwidth and by decrease cell size. handover is occurrent and increment connection failure ratio In this result. IEEE 802.16 standard is support seamless connection through handover optimization scheme. But because authentication process is abbreviate, network weakness is exposure. In this paper, we propose handover scheme for support realtime service as VoIP, Picure communication, Streaming Data Service in order to support partially encryption method. In experiment, proposed scheme is proof which process time is increment 20% more than previous scheme.

• Korean Journal of Community Nutrition
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• v.8 no.6
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• pp.977-985
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• 2003

This study was done to evaluate the health and nutritional status of female college students in Seoul. The subjects were 63 healthy college students aged 20 to 29 years. Their body composition, dietary intakes, clinical blood indices were investigated. Their body composition was determined by means of a multifreqency bioelectrical impedance analysis. Their dietary intake was determined using 3-day record method and their nutrient intake was analyzed by Computer Aided Nutritional analysis program for professional (CAN-pro). Their hemoglobin, hematocrit, red blood cell (RBC), white blood cell (WBC) and mean corpuscular volume (MCV) were determined by semi-automated microcell counter (F-520). Their plasma total cholesterol, TG, and HDL-cholesterol levels were measured using test kits. All data were statistically analyzed by SAS PC package program. Their average consumption of calcium, iron vitamin A, vitamin B2 and niacin were 63.3%, 65.0%, 85.2%, 89.2% and 95.2% of RDA, respectively. The overall mean values of the hematological indices in the female college students were within the normal range. However anemic subjects with hemoglobin (< 12 g/dl) and hematocrit (<36%) accounted for about 20% of the subjects. The mean levels of total cholesterol, HDL-cholesterol and TG were 188.4mg/dl, 69.9mg/dl and 67.4mg/dl, respectively. The percentages of the subjects with plasma total cholesterol level (> 200mg/dl) and LDL-cholesterol (＞130mg/dl) were about 41% and 30.4%, respectively. The data showed a significantly positive correlation between either body fat (%) or BMI and TG. However. there was a significantly negative correlation between either body fat (%) or BMI and HDL-cholesterol. These overall results suggest that it is necessary for college women to be educated regarding consuming more iron and vitamin C and less fat, in order to prevent iron deficiency anemia and/or cardiovascular diseases in later life.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.21 no.3
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• pp.301-306
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• 2010

In this paper, a SIT(Source Independent Tree) method for ray tracing is proposed to enhance the efficiency of tree construction with reuse of sub tree in urban environment, As the SIT method is applied, the decrease of the number of nodes for picocell and microcell simulations is 100 times. And 88~98 % of the total nodes are reused with change of location of signal source from an analysis of node reuse efficiency. Therefore the proposed SIT method is useful in performance enhancement of ray tracing, especially, for multiple antenna simulation like as MIMO system and cell planning.

• Korean Journal of Community Nutrition
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• v.11 no.3
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• pp.307-316
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• 2006

This study was conducted to investigate the relationships among body composition, dietary intake, and clinical blood indices in college students by body mass index (BMI). Their body compositions were determined by means of BIA (Bioelectrical Impedance Analysis) method. Their dietary intake was determined using a 3-day record method and their hematological indices were determined by semi-automated microcell counter (Sysmex F-520). Their serum lipid levels were measured using biochemical analyzer (Spotchem). Subjects were classified as underweight, normal or over-weight groups according to their BMI. The subjects were 69 healthy college students aged 20 to 26 years. The average age, height, weight, and BMI was 21.3 years, 162.6 cm, 54.4 kg, and $20.6cm/m^2$, respectively. Their average consumption of energy was 1693 kcal, 84.7% of RDA and their mean ratio of carbohydrate: protein: fat were 54.5 : 16.4 : 29.0. There was no significant difference in nutrient intake among the groups except ${\beta}$-carotene and vitamin C. The ${\beta}$-carotene intake was significantly higher in the underweight group. Vitamin C intake was significantly higher in the overweight group. The mean intakes of Ca, Fe, Zn and folate of subjects were 74.8% to 83.2% of RDA. Especially, intakes of Ca, Fe, Zn and folate were lower in the abnormal weight groups. The overall mean values of the hematological indices in female college students were within the normal range and there was no significant difference among the groups. However, anemic subjects with hemoglobin (< 12 g/dl) and hematocrit (< 36 g/dl) accounted for about 11% of the subjects. The everall mean values of the serum lipid levels were within the normal range and there was no significant difference among the groups. But serum HDL-cholesterol level of the overweight group was lower than that of the other groups. LDL-/HDL-cholesterol ratio and AI index were significantly higher in the overweight group compared to the other groups. Based upon this study, it is necessary for college women to be educated regarding consuming more Ca, Fe, Zn, folate and less fat and cholesterol in order to have better health promotion.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.9 no.4
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• pp.427-438
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• 1998

The bit error rate(BER) performance of Trellis Coded QPSK signal in the presence of cochannel interference (CCI) and Rician fading is investigated. The trellis coded QPSK system adopts Maximum Ratio Combining (MRC) diversity reception and Reed-Solomon code to enhance system performance. Using the derived error probability equation, the error performance of trellis coded QPSK system has been evaluated and shown in figures to discuss as a function of signal power to noise power ratio (SNR), signal power to interference power ratio(SIR), direct to indirect signal power ratio ($K_R$), the number of diversity branch (M), the frame length of Reed-Solomon code (n), the number of error correction symbol (t), and the number of state of trellis encoder. From the results, we know that proposed system is affected by cochannel interference and fading in microcell environment. Also, BER performance of Trellis Coded QPSK system can be improved as increasing either the power of desired signal or the value of SIR. And the BER floor in microcellular system is caused by the cochannel interference and it occurs at high BER when SIR is low. And Reed-Solomon code (n=15, t=2) is more effective to restrain the affection of CCI and fading than MRC diversity reception (M=2).

• The Transactions of the Korea Information Processing Society
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• v.4 no.7
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• pp.1804-1820
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• 1997

In this paper, an efficient call control procedure is presented for next generation wireless ATM networks and its performance is mathematically analyzed using the open queueing network. This procedure is based on a new scheme called as the cell clustering. When we use the cell clustering scheme, at the time that a mobile connection is admitted to the network, a virtual cell is constructed by choosing a group of neighboring base stations to which the call may probabilistically hand over and by assigning to the call a collection of virtual paths between the base stations. Within a microcell/picocell environment, it is seen that the cell clustering can support effectively a very high rate of handovers, provides very high system capacity, and guarantees a high degree of frequency reuse over the same geographical region without requiring the intervention of the network call control processor each time a handover occurs. But since mobiles, once admitted, are free to roam within the virtual cell, overload condition occurs in which the number of calls to be handled by one base station to exceed that cell site's capacity of radio channel. When an overload condition happens, the quality of service is abruptly degraded. We refer to this as the overload state and in order to quantify the degree of degradation we define two metrics, the probability of overload and the normalized average time spent in the overload state. By using the open network queueing model, we derive closed form expressions for the maximum number of calls that can be admitted into the virtual cell such that the two defined metrics are used as the acceptance criteria for call admission control.