• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.19 no.1
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• pp.23-32
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• 2008

In the VHF range, active antennas are widely used for wideband applications due to their small size. Active antenna consists of antenna elements and amplifiers, which are directly connected to each other. Gain and noise-figure characteristics are very important for good sensitivity performance, because it is located at the front end of a receiving system. In this study, we developed an active dipole antenna with 5:1 bandwidth(100${\sim}$500 MHz), which consists of a dipole antenna and a P-HEMT amplifier. To obtain required performances, the antenna and the amplifier should be designed simultaneously. In order for that, we introduced an equivalent port concept to model the 1-port dipole antenna as an equivalent 2-port system. Using the proposed equivalent port, the performance of the active dipole antenna was simulated by the ADS. In order to measure the gain and noise-figure characteristics of the antenna, we utilized the same concept of the two-port equivalent impedance model. The measurement results for typical gain, NF and VSWR in the required frequency band were 8dBi, 9dB and 1.7:1, respectively. The radiation patterns at the principal planes were same as the typical radiation pattern of a dipole antenna. By comparing the simulation results with measured ones, it is confirmed that the proposed methods works well.

• Journal of the Korea Organic Resources Recycling Association
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• v.28 no.1
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• pp.65-72
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• 2020

The aims of this study were to compare the biomethanation of CO₂ through specific methanogenic activity (SMA) test which was inoculated with four different types of mixed microbial culture obtained from full-scale anaerobic digestion (AD) plants. The experimental results showed that CH₄ conversion was the highest in the samples inoculated by seed sludge taken from ADs of food waste and brewery; under this condition, the produced biomethane contains 89.3-91.9% of CH₄. Meanwhile, the lowest level was obtained in the sample from sewage sludge. The measured ratio of CH₄ production rate to CO₂ consumption rate in all reactors was higher than the theoretical value (1) in the middle of the period and soon dropped to 0.7-0.8. It might be due to changed metabolic pathways in the reactor by the degradation of residual organic matter and the increased activity of homoacetogenic bacteria.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.33 no.8C
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• pp.575-582
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• 2008

In this paper we described the process and the results of real-time implementation of G.729.1 wideband speech codec which is standardized in SG15 of ITU-T. To apply the codec on ARM926EJ-S(R) processor core. we transformed some parts of the codec C program including basic operations and arithmetic functions into assembly language to operate the codec in real-time. G.729.1 is the standard wideband speech codec of ITU-T having variable bit rates of $8{\sim}32kbps$ and inputs quantized 16 bits PCM signal per sample at the rate of 8kHz or 16kHz sampling. This codec is interoperable with the G.729 and G.729A and the bandwidth extended wideband($50{\sim}7,000Hz$) version of existing narrowband($300{\sim}3,400Hz$) codec to enhance voice quality. The implemented G.729.1 wideband speech codec has the complexity of 31.2 MCPS for encoder and 22.8 MCPS for decoder and the execution time of the codec takes 11.5ms total on the target with 6.75ms and 4.76ms respectively. Also this codec was tested bit by bit exactly against all set of test vectors provided by ITU-T and passed all the test vectors. Besides the codec operated well on the Internet phone in real-time.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.19 no.11
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• pp.1193-1203
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• 2008

An active antenna(AA) can have wider bandwidth and more gain with small antenna size than those of passive antennas. However, AA inherently generates thermal noise and spurious signals from an active device. Moreover, the spurious performance of AA is very important in a highly sensitive receiving system since it is located at the front end of the receiving system. In this study, we developed an AA with $100{\sim}500\;MHz$, having the output P1dB higher than 3 dBm and little spurious signals in real environments. To achieve such performance, we designed an AA with 3-stage amplifier using CD(common drain) FET and 2 BJTs. Its electrical performances were simulated using ADS. The measurement results for typical gain, NF, OIP3, VSWR and P1dB in the required frequency band were 9.7 dBi, 10 dB, 14 dBm, 1.7:1 and 3 dBm respectively. They are in good agreement with simulation results. The unwanted spectrum level of the proposed AA is $10{\sim}30\;dB$ lower than that of the antenna with CS(common source) FET configuration at a west suburban area of Seoul, which shows that the proposed AA can be applicable to a highly sensitive receiving system for detecting unknown weak signals mixed with broadcasting and civilian communication signals.

• Journal of the Korean Dietetic Association
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• v.10 no.2
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• pp.159-173
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• 2004

The desire for the healthy life is increasing as a result of rapidly changing social and economic environment in Korea. Because of the need, informations on health, food and nutrition are being introduced through the mass media. The object of this study is to investigate and analyze the quantity and quality of informations about health, food and nutrition in women's magazines. Six representative domestic monthly magazines(Lady Kyunghyang, Women Donga, Women Chosun, Women JoongAng, Women sense, Jubu Senghwal) were selected for this study. The results of monitoring from June 2002 to September 2002 for the women's magazines were summarized as follows; 1. The percentage of the articles on health, food and nutrition by total area of the women's magazines was 23.1%. There were total 595 articles on health, food and nutrition. Among these, 400 articles(67.2%) were about food and nutrition. 2. The percentage of the advertisements on health, food and nutrition was 35.3% by total area of the woman's magazines. There were 2,353 advertisements on health, food and nutrition. Among these, 1,574(66.9%) advertisements were about food and nutrition. The most frequently advertised advertisements on food and nutrition were about processed foods (527 cases, 33.5%). The second most frequently advertised advertisements were about diet (374 cases, 23.8%). The third one was healthy foods (345 cases, 21.9%). 3. The contents of 215(53.8%) articles (the total number of articles was 400) was suitable. The contents of 89 advertisements(22.3%) did not have accurate informations on health, food and nutrition. For the advertisements in women's magazines (the number of total articles was 2,203), the percentage of the advertisements which was not able to capture the feature of the advertisements was 27.9%, insufficiency of reliable sources was to 21.9%, and exaggeration of the contents in the ads was 16.0%. Articles and advertisements should be backed by scientific research or reliable sources and also the opinions of people with expertise in order to report accurate informations to the general public. In order to achieve these results, there should be continuing monitoring activity for the women's magazines.

• Journal of Hospice and Palliative Care
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• v.23 no.3
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• pp.126-138
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• 2020

Purpose: In Korea, since the Act on Hospice and Palliative Care and Decisions on Life-Sustaining Treatment for Patients at the End of Life was implemented in February 2018, advance directives (ADs) have become legally effective and should be documented after sufficient explanation by a registered counselor. However, little is known regarding the adequacy of current AD counseling. This qualitative study aimed to explore the barriers to AD counseling based on counselors' experiences. Methods: We conducted focus group interviews using purposive sampling. Seven counselors working at hospitals, community health institutions, and non-profit organizations participated in this study. They were asked about the challenges and problems they encountered during AD counseling. Results: Three themes emerged from this study; 1) issues regarding consistency in AD counseling, 2) issues regarding AD counselors' competency and work environment, and 3) issues regarding the adequacy of the service system. The interviewees stated that the lack of a manual for standardized service made AD counseling inconsistent. The limited competency and poor work environment of counselors were pointed out as major barriers. The interviewees also stated that a proper service system considering individual circumstances is absent. Conclusion: The goals of AD counseling should be clarified and guidance should be implemented for providing standardized services. Further efforts to enhance the competency of AD counselors and to improve their working conditions are needed. Establishing an integrated framework for an adequate service system is also essential to overcome systematic barriers to AD counseling.

• Journal of the Korean Academy of Child and Adolescent Psychiatry
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• v.21 no.3
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• pp.161-167
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• 2010

Objectives: In assessing behavioral/emotional problems in school-aged children, the importance of multi-informant reporting has been well documented. However, in clinical settings obtaining multiple informants' opinions has proven difficult. For that reason, we researched the agreement and predictive validity of the Child Problem-Behavior Screening Questionnaire (CPSQ) in order to reveal how accurate parents' assessments reflected teachers'opinions. Methods: We conducted the first screening for second- and third-grade children from 3 elementary schools in Seoul from 2003 to 2007 using the CPSQ. There were 1178 children included in the analysis. We then administered the Korean version of the Child Behavior Checklist (K-CBCL) as a second screening tool and subsequently, the ADHD Diagnostic System (ADS) and the Korean Educational Development Institute version of the Wechsler Intelligence Scale for Children (KEDI-WISC) was administered by a psychiatrist. We examined each item on the CPSQ and the subscale's agreement between parent and teacher as well as the predictive validity of the CPSQ in children diagnosed with emotional/behavioral problems. Results: The agreement rates between parents and teachers appeared high for questions 18 (0.433), 1 (0.385), and 2 (0.325). Among the subscales, a relatively high correlation was found for externalizing problems, attention deficit hyperactivity disorder, and cognitive problems. For all diagnosed children, their parents revealed a higher sensitivity and lower specificity than teachers. Conclusion: From these results, we confirmed that the CPSQ can be useful for sorting out externalizing and cognitive problems. There is a need for further study, however, with a larger sample size.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2007.10a
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• pp.242-245
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• 2007

To improve the efficiency of PDP TV, it should minimize the power losses transpired during AC-to-DC power conversion and PDP driving process. Generally the input power supply for PDP driving employes a two-stage power factor corrected converter, and it independently consists of sustain driver, which has high power consumption. However, such a circuit configuration has a difficulty for the PDP market requires low cost. To alleviate this problem, a new circuit composition is presented. It integrates input power supply with sustain driver in a single power stack. The input power supply of the proposed circuit has a single-stage structure to minimize power conversion loss, and it directly supplies power to the sustain driver so as to reduce the system size and cost.

• Journal of the Korean Home Economics Association
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• v.42 no.3
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• pp.105-118
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• 2004

Cable TV Home Shopping is one of the popular distribution channels in modem society because of purchasing convenience and saving in shopping time. However, in spite of these advantages, there are some problems because of marketing strategies of many Cable TV shopping companies which stimulate impulse purchases. This study is aimed to find the relationship between buying experience and reaction to impulsive buying stimulus. This study can give a valuable insight in consumer education regarding impulsive purchase behavior in Cable TV home shopping. Study results can also give useful information on the direction of consumer campaign and consumer protection policies. The data was collected by using a questionnaire and the final 496 cases were analyzed by SPSS Win 10.0 program. The major finding were that: 1. Younger, more educated and unmarried consumers tend to response more to impulsive purchasing stimulus. 2. consumers with higher response to impulsive purchasing stimulus had more buying experience, higher shopping frequencies and spent more money in Cable TV home shopping than consumers with lower response. These study results showed that there are some relationship between impulse purchasing stimulus and buying experience in Cable TV home shopping. Therefore, Cable TV Home Shopping companies should provide correct information to the consumers, so they can make resonable decisions. And the consumers should also try to restrain themselves from purchasing impulsively. A law that will regulate all false or exaggerated ads should be provided. To reach righteous and beneficial home shopping culture for both consumer and companies, all these means should be cooperated.

• Journal of Korea Society of Industrial Information Systems
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• v.18 no.3
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• pp.1-8
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• 2013

Plasma display panel (PDP) televisions are facing to have a new chance to receive attention along with a boom in 3-D software and contents because PDP can provide the comfortable and realistic 3-D images. The PDP has three driving circuit boards such as X, Y and addressing boards. Cost effective driving waveform has already been reported to decrease the number of driving circuit board. Half bridge based sustaining driver can remove a sustaining driver in the X board. However, the biasing circuit in the X driving boards cannot be reduced because there are some drawbacks such as unstable gas discharge condition and unreliability of an address driver IC. In this paper, the half bridge based sustaining driver is considered and a simple address driver is proposed to remove one driving board, X driving board. The stable gas discharge condition, reliability of the address driver IC and the low cost can be obtained by the proposed circuit.