• Journal of the Korean Society of School Health
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• v.9 no.2
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• pp.249-266
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• 1996

AIDS and the spectrum of Human Immunodeficiency Virus(HIV) infections present a monumental challenge to the health of the Korean public. In response to this special challenge, I think public education and voluntary behavior changes are the most effective measures to fight the spread of the disease. Adolescents represent a critical risk group for prevention and intervention programming. Research indicates sexually active adolescents, homosexual contact, illicit drug use are an gradually increasing. These characteristically adolescent risk-taking behaviors suggest the need for schools and communities to mobilize intervention strategies. Schools are highly efficient ways to reach a majority of young people in Korea with HIV prevention programs. These programs include substantial attention to sexual and drug use behaviors with the long term objective of a multidimensional school health program. Information resulting from risk behavior surveillance activities and guidance on school health curricula is particularly useful. What is needed for adolescents is a revamping of education to give students the critical thinking and analytic skills that allow them to apply knowledge, make decisions, and think independently. The best HIV preventive education provides young people with opportunities to learn and practice just those skills. In the early stages of HIV education were focused solely on information. Providing information is easy but unfortunately, behavior change is not that simple to activate. Information must be combined with values exploration and skilly building, including responsible decision making, negotiation, refusal, and critical thinking skills. The same knowledge, attitudes and skills needed for effective HIV prevention also prevent or reduce other risks, including other sexually transmitted diseases, unwanted pregnancies, and alcohol or other drug use. The role of other youth serving organizations in HIV prevention is also important: parental and youth involvement is needed; it's important to presidential and governament leadership is essential to prevention education; promote integrated adolescent programs, to enhance health and education sector collaboration; and of course, we need to expand research on adolescent health and engage the media in health promotion. Among these changes, a school-based systematic health education of AIDS is certainly one of the essentials.

• Korean Journal of Clinical Laboratory Science
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• v.45 no.2
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• pp.43-47
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• 2013

This study was designed to evaluate the prevalence of ESBL genes and monitor antimicrobial resistance pattern in Escherichia coli, isolated from a hospital and a community. We tested 200 E. coli strains isolated in the hospitals and community in Chungcheong area from January to March 2012. Antimicrobial susceptibilities were tested by using the disk diffusion method. A search for ESBL genes was conducted by PCR amplification, and the genotypes were determined by direct nucleotide sequence analysis of the amplified products. An Epidemiologic study was performed by repetitive extragenic palindromic sequence-based PCR (REP-PCR). The percentage of ESBL-producing isolates was 17% for hospital associated E. coli and 11% for community associated E. coli. The ESBL gene sequencing results showed that the most common ESBL in E. coli was CTX-M-14 (19/28), followed by CTX-M-15 (9/28). The REP-PCR study also showed the genetic diversity, but there was no difference between the hospital and community associated E. coli. In this study, the most common types of class A ESBLs identified were CTX-M in the hospital and the community in Chungcheong area. ESBL-producing E. coli isolates showed diverse clonality.

• Journal of the Institute of Convergence Signal Processing
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• v.8 no.1
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• pp.44-50
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• 2007

In this paper generating algorithms of the conventional chaos code sequences and a new chaos code sequence derived from the real and imaginary parts of FFT of one chaos code sequence, and the time-frequency function characteristics of generated code sequences to measure the signal resolution, are considered. And two chaos based QCSK digital communication systems-one with two different chaos code sequences, the other with FFT of one chaos code sequence-are analyzed in AWGN and fading communication channels. After analyzing the correlation functions of such sequences, the delta-like autocorrelation and near zero crosscorrelation functions of them are very suitable for chaos based spread spectrum communication systems, is verified. Through evaluating the performance of two chaos based QCSK systems above using Monte-Carlo simulation, the improvement of performance in the latter QCSK system compare favorably with that of the former system, is shown.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.24 no.10A
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• pp.1462-1470
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• 1999

In this paper, the performance of packet radio networks using the ALOHA protocol in Rayleigh fading channels is analyzed in terms of the capture probability and the throughput. We consider capture effect in order to increase the probability of the channel access and to include cellular environment we assume that the traffic is a truncated bell-shaped distribution. The packet proposed in this paper consists of a competition part and a data part to decrease the probability of collision in the channel access. In the competition part, DS system with common spreading code is used and in the data, hybrid DS/FH system is used. We consider the linear correlation receiver and the hard-limiting correlation receiver as the receiver model. BPSK modulation is also employed. Because hybrid DS/FH systems are not sensitive to variation of the interference power, as we choose a proper chip number N and a frequency hopping number q, we can obtain a steady system performance even though the variation of interference power is severe fading channels such as Rayleigh fading.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.13 no.3
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• pp.316-322
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• 2002

The Orthogonal Frequency Division Multiplexing(OFDM) is a special case of multicarrier transmission, where a single data stream is divided into many subcarriers and transferred in a parallel way. It reduces the necessary bandwidth using the orthogonality between the subcarriers. Therefore it requires the transmission channel which has stable characteristic. When the delay spread of the channel exceed the guard interval, then the orthogonality of the subcarriers cannot maintain and as a result the system performance degrade. In this paper, the XCP-OFDM(OFDM using cross-handed Circular Polarization) system is newly proposed. This system divides the channel in order to eliminate the overlapping of subcarrier's spectrum by using cross-handed circular polarization. Therefore, the proposed XCP-OFDM system can improve the performance without increasing the guard interval. Both theoretical analysis and simulation results are described.

• The Journal of the Acoustical Society of Korea
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• v.33 no.6
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• pp.407-412
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• 2014

In this paper, we propose an underwater acoustic communication of FH-MFSK(Frequency-Hopped Multiple Frequency Shift Keying) system with multiple orthogonal property. Generally, the processing of FSK(Frequency Shift Keying) method is simple, but it is vulnerable to ISI (Inter-Symbol Interference) caused by multipath transmission. In this paper, the orthogonal codes are generated with the same number of transmitting symbols, and these codes are corresponding to multiple frequencies. We used m-sequence to generate multiple orthogonal codes. We compared the performance of proposed method with conventional MFSK method via the experiment. As a result, we confirmed that the proposed method shows 6~10 % lower error rate at 100 bps than conventional method.

• Fire Science and Engineering
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• v.30 no.5
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• pp.124-129
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• 2016

According to the current law, on-site flame resistant-treated interior decorations should pass the flame resistant performance test through a 45 degree combustion test from the district fire department. Although a 45 degree combustion test is the most accurate method for determining the flame resistant performance, it can be unreliable when tested on unauthorized samples. To avoid unauthorized sampling, this study suggests on-site flame resistant inspection by X-ray fluorescence spectrometer. Ten types of flame resistant paint were spread on plywoods and MDFs and the components were analyzed by X-ray fluorescence spectrometer. As a result, due to a difference amounts of substances in each paint, each flame resistant paints showed its own characteristic spectrum and the contents of each substance could be determined. On-site flame resistant inspections can be used efficiently when institutional procedures are created.

• Korean Journal of Environment and Ecology
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• v.21 no.1
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• pp.1-12
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• 2007

Nauralized plants in Ulleungdo were enlisted as 65 taxa, 21 families,49 genera,63 species and 2 varieties by field survey and flora lists of literature cited. Family Compositae covered 27.7% and Family Gramineae, Family Leguminosae and Family Polygonaceae covered 7.7% each. In this study, the nine taxa such as Rumex nipponicus, Trifolium campestre, Oxalis articulata, Anthriscus caucalis, Ipomoea purpurea, Coreopsis Ianceolata, Galinsoga parviflora, Tritonia crocosmaeflora and Festuca arundinacea are added as Nauralized plants in Ulleungdo. Annual plants ratio is 36.9% by life-form spectrum and Europe ratio is 40.0% by origin. The Urbanization Index was 22.0 and the Ratio of Naturalized has increased by flora lists of literature cited each. Ambrosia artemisiifolia var. elatior is growing in Ulleungdo by a plant cause disturbance. Spread prevention and minimization incoming of gardening plants by management plan of naturalized plants might be required. Moreover, it is needed to induce the succession for the recovery of the cut-slope using the native plants.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.31 no.6A
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• pp.627-633
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• 2006

In spite of many advantages of Meteor Burst Communications(MBC) on its transmission channel, the fact that its duty rate is less than 10 percents is a considerable deficiency of MBC. To overcome with this deficiency without paying large cost, we use a direct sequence(DS) simple reception system. This method doesn't need to add the components for acquisition or tracking the signal so that it keeps the cost efficiency of the MBC. But it has a disadvantage that its duty rate shows a large decline by noise. For this problem we adopt the proposed system applying a transversal filter circuit. The improvement by this method is more significant when the received signal is weak Simulation results show as t1 is 100ms, then the burst length would be increased by 35% when the initial value of the received signal power increases by 3 dB, t2 is 135ms. If the power increases by 6dB the burst length would be 170ms thus increased by 70%, which shows a great enhancement. Suppose now that t1 is 50ms and the power is increased by 3dB, then t2 would be increased by 70% to 85ms, and increasing the power by 6dB it would be increased by 130% to 115ms.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.17 no.9
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• pp.939-950
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• 1992

The performance of common spreading code scheme employing multiple-capture receiver is compared to that of transmitter-oriented (T/O) code division multiple access (CDMA) scheme in view of the possibility of collision-free transmissions and the effect of secondary multiple-access interference. For performance comparisons, secondary multiple-access interference is characterized for the common code scheme and the T/O CDMA scheme that assures perfectly collision-free transmissions. Throughput performance is then evaluated for these two schemes with direct-sequence spread-spectrum/differential-phase-shift-keying (DS-SS/DPSK) data modulation and forward-error-control coding (BCH codes) in the presence of an additive white Gaussian noise (AWGN). It is shown that when the number of radios is relatively large, the maximum normalized throughput is greater for the common code scheme than for the T/O CDMA scheme at a moderate signal-to-noise ration(SNR).