• Proceedings of the Korea Society for Industrial Systems Conference
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• 1999.12a
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• pp.121-129
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• 1999

When continuous media are transmitted over the communication networks, asynchrony which can not maintain temporal relationships among packets may occur due to a random transit delay. There exist two types of synchronization schemes ; for guaranteed or non-guaranteed resource networks. The former which applies a resource reservation technique maintains delay characteristics, however, the latter supply a best-effort service. In this paper, I propose a intra-media synchronization scheme to transmit continuous media on general networks not guaranteeing a bounded delay tome. The scheme controls transmission times of the packets by estimating next delay time with the delay distribution. So, the arriving packets may be maintained within a limited delay boundary, and playout will be performed after buffering to smoothen small delay variations. The continually increasing delay due to network overload causes buffer underflow at the receiver. To solve it, the transmitter is required to speed up instantaneously. Too much increase of transmission-rate may cause network congestion. At that time, the transmitter drops the current packet when informed excessive delay from the receiver.

• Korea journal of population studies
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• v.29 no.2
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• pp.1-26
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• 2006

This paper examines the interplay among changes in socioeconomic conditions, population policies, and fertility decline during $1960{\sim}2000$ in South Korea. Period-parity-progression-ratios (PPPR) are calculated using 2% samples of Population Census with the implied distribution of completed family size. The total fertility rate based on PPPR declined from 5.21 in 1960 to 2.76 in 1980, and 1.69 in 2000. The family planning programs were successful in meeting the needs of families that wanted to prevent further childbearing after having achieved the desired family size during $1960{\sim}1970$. The 1980s mark two important landmarks: achievement of replacement fertility and emergence of high sex ratio at birth. In the 1990s the "quality and welfare" approach was emphasized. In 2000s, South Korea's fertility is one of the lowest in the world. In response to this, in 2005, the Government adopted a new population policy with the goal of increasing the total fertility level to 1.6 by 2010. The results of this study indicate that proportion of women who would have no children at all throughout their reproductive life span increased substantially from 10% in 1995 to 16% in 2000, with a sharp increase since 1997. Thus, pro-natal programs need to address the problems associated with marriage and having the first child. Towards that, it is important that work and family life become more compatible.

• 한국지구과학회:학술대회논문집
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• 2005.09a
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• pp.231-244
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• 2005

이 연구는 고등학교 지구과학 탐구활동에서 소그룹활동을 학생들의 대화를 중심으로 분석하고, 반성적 탐구활동이 교육과정별로 어떤 차이를 보이고 소그룹내의 상호작용특성에 따라 반성적 탐구양식의 차이가 어떠한지 알아보는 것이다. 그럼으로써 학생들이 어떤 반성적 탐구양식을 보이며 어떻게 발달시키는지에 관한 이해를 제공하고, 수업속의 맥락은 이러한 반성적 탐구학습을 증진시키고 억압하기위해서 어떻게 상호작용 하는지를 알아보고자 하였다. 이에 대한 연구문제로 소그룹을 이용한 탐구활동 수업과 반성적 탐구활동수업 중 반성적 에피소드의 차이가 있는가, 소그룹내의 그룹상호작용의 특징에 따른 반성적 탐구유형의 차이는 있는가를 설정하였다. 이를 위해 고등학교 1학년 2개 학급을 선정 기존의 우리나라 교육과정에 의거한 탐구활동수업 4차시, 반성적 탐구교육과정 수업 4차시를 각각 실시하고 수업을 녹화 전사해서 언어행동 분석틀과 반성적 탐구의 3가지 맥락을 통해 분석하였다. 연구 결과 두 교육과정 모두 도입에서 두 교육과정 모두 A-AD맥락의 반성적 탐구가 전형적으로 자주 나타나며, 반성적 탐구 교육과정수업에서는 AD-SR가 주로 나오는 것으로 보아 과제활동초기에 역할 분담과 과제 활동의 전략을 세우며, 전략을 세울 때 영역개념을 이용하는 것을 안수 있었다. 우리나라 교육과정 수업에서는 반성적 탐구진술이 간단하고 계획과정이 짧으며, 주로 과제 맥락 내에서 반성적 탐구를 하는 것으로 나타났다. 전개부분에서는 두 교육과정모두 DI-DP, DI-A맥락의 반성적 탐구가 나타나 자료 항목과 자료 패턴 그리고 인공물과 관련시키는 반성적 탐구가 공통적으로 나타나며 반성적 교육과정수업에서는 대체로 자료 맥락의 영역개념과 과제 맥락을 연결시키는 반성적 탐구가 잘 나타나고 있다. 반면 우리나라 교육과정에서 주로 과제 맥락 내에서 반성적 탐구가 나타났다. 정리단계에서는 반성적 교육과정 수업에서는 DC-DP가 주로 나타났으며 우리나라 교육과정수업에서는 DC-DP DP-AD맥락의 반성적 탐구가 나타났다. 정리활동에서 우리나라 교육과정은 반성적 교육과정보다 자료 맥락의 영역개념을 더 자주 이용하고 다양한 맥락의 반성적 탐구가 나오고 있으며, 이는 우리나라 교육과정의 학습지의 활동이나 문제는 학생들에게 익숙하고, 자료 패턴을 가지고 행동결정으로 연결짓는 활동이 명확히 제시되었기 때문이라고 판단된다. 두 그룹의 상호작용 특징에 따른 반성적 탐구의 성향의 차이는 도입단계에서 그룹의 특징과 상관없이 A-AD, AD-SR맥락의 반성적 탐구가 나왔으며 전개와 정리단계에서는 N그룹에서는 DP와 관련된 의미 있는 반성적 탐구가 나오는 반면 M그룹에서는 이러한 맥락의 반성적 탐구는 아주 드물게 나타나며, GN과 관련된 행동결정이 자주 보이고 있었다. 정리활동시 주로 하는 기록 활동에서 N그룹에서는 다양한 맥락에서 반성적 탐구를 하고 있는 것에 비해 비교 그룹에서는 서로 견제하고 확인하는 상호작용의 특징에서 나타나는 AD-SR맥락의 반성적 탐구가 자주 나타났다. 반성적 탐구 척도 두 그룹을 비교 했을 때 CON 상호작용의 특징이 낮게 나타나는 N그룹이 양적으로 그리고 내용적으로 더 의미 있는 반성적 탐구를 했다

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.18 no.1
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• pp.129-136
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• 2004

In this paper, we proposed quad variable rates ADPCM coding method for efficient speech transmission and real time porcessing is implemented on TMS320C6711-DSP. The modified ADPCM with four variable coding rates, 16[kbps], 24[kbps], 32[kbps] and 40[kbps] are used for speech window samples for good quality speech transmission at a small data bits and real time encoding and decoding is implemented using DSP. ZCR is used to identify the influence of the noise on the speech signal and to decide the rate change threshold. For noise superior signals, low coding rates are applied to minimize data bit and for noise inferior signals, high coding rates are applied to enhance the speech quality. In most speech telecommunications, silent period takes more than half of the signals, speech quality close to 40[kbps] can be obtained at comparabley low data bits and this is shown by simulation and experiments. TMS320C6711-DSK board has 128K flash memory and performance of 1333MIPS and has meets the requirements for real time implementation of proposed coding algorithm.

• The Transactions of the Korea Information Processing Society
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• v.3 no.1
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• pp.127-143
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• 1996

Advanced countries are very active in deploying the National Information I infrastructure which provides universal service to promise fruitful quality of futuree life. Even in the distributed environment, we can closely converse, work together, and share information in a very convenient way. This is actually enabled with the help of groupware technology, which are currently focused and researched in a larger popularity. The aim of this study is to design a portable pack for group communications management to support the development of groupware application. In the paper we begin with technical survey, continue to build our own model for group communications man agement, and design its architecture and procedure. We also suggest group addressing mechanism under Internet environment such as how to create IP multicast address and IP port number dynamically and as a globally unique value for the communication session, with the help of the hierarchical and distributed address managers. We also indicate the reliable data transmission services to remedy the unreliable feature of the UDP multicast services, and finally the architecture/ applied to support the practical applications is briefly discussed for verification of the designed concept.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.3
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• pp.537-543
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• 2016

This paper suggests a class model to improve the English oral proficiency for intermediate low English speaking learners. Utilizing the four English skills (reading, writing, listening and speaking), the class model focuses on the learners' schema and discussion strategies. To enhance the learners' motivation and match their cognitive capacity, 10 discussion topics were prepared by surveying the learners. A pilot experiment was conducted to investigate the teaching effects of the discussion class model with 26 college students majoring in English in Seoul. The participants' oral proficiency was measured both before, and after the instructions by OPIc (Oral Proficiency Interview in computer). As a result of the experiment, the percentage of participants whose oral proficiency levels were lower than intermediate mid decreased from 82% to 47%. In addition, the percentage of participants with higher oral proficiency than intermediate low was increased dramatically from 18% to 53%, which supports the claim that through discussion, the class learners' diverse and creative ideas need to be expressed in a formal and intelligible language. Finally, through the findings of the study, the possibility of a discussion class can be expected, regardless of the learners' low level of oral proficiency.

• Journal of Science Education
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• v.39 no.2
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• pp.180-208
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• 2015

The purpose of this study was to investigate secondary students' perception of a good secondary science classes. Subjects were 18 secondary students who enrolled in alternative school located in Korea. The instruments of this study was a questionnaire which consisted of 18 items on 4 domains. Also data were collected from in-deep interviews and students' drawing. The results of the study were summarized as follows; First, students explained that good schools have the characteristics of the interesting and respectful atmosphere. Also there are good relationships between teachers and students. Second, they emphasized that good teachers are humanistic teachers. Third, good science classes are based on the constructivism in terms of the education methods. The results suggest that it may be necessary to remodel the merits of the alternative schools to solve the problem of public school. It is important to develop expertise of the science teachers in alternative school through teacher education programs based on the constructivism. Also it is necessary to provide appropriate learning space and various media for effective science teaching and learning in alternative school.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.38 no.3
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• pp.253-263
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• 1993

Climatological informations have not been fully utilized by agricultural research and extension workers in Korea due mainly to inaccessbilty to the archived climate data. This study was initiated to improve access to historical climate data gathered from 72 weather stations of Korea Meteorological Administration for agricultural applications by using a microcomputer-based methodology. The climatological elements include daily values of average, maximum and minimum temperature, relative humidity, average and maximum wind speed, wind direction, evaporation, precipitation, sunshine duration and cloud amount. The menu-driven, user-friendly data retrieval system(CLIDAS) provides quick summaries of the data values on a daily, weekly and monthly basis and selective retrieval of weather records meeting certain user specified critical conditions. Growing degree days and potential evapotranspiration data are derived from the daily climatic data, too. Data reports can be output to the computer screen, a printer or ASCII data files. CLIDAS can be run on any IBM compatible machines with Video Graphics Array card. To run the system with the whole database, more than 50 Mb hard disk space should be available. The system can be easily upgraded for further expansion of functions due to the module-structured design.

• Economic and Environmental Geology
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• v.36 no.2
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• pp.123-131
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• 2003

Geophysical surveys(electrical resistivity, self-potential, seismic refraction, GPR) were conducted to investigate the physical properties of the subsurface, and to delineate the flow channel of leachate from a AMD(acid mine drainage), buried rock wastes and tailings, and drainage pipes at an abandoned mine(Kwangyang mine). Especially in rainy season the sites appear to be abundant in AMD leachate, characterized by electrical conductivities of 0.98-1.10 ms/S. Electrical resistivity sections indicate that the leachate flows running in two directions at southern part rise up through the narrow fracture zones at the central part and contaminates the surrounding soil and stream. Such schematic features at the anomalous zone are well correlated with negative peaks in self-potential data, the limited penetration depth in GPR data and low velocity zone in seismic refraction data. Shallow high-resistivity zone is associated with the buried rock wastes which cause the diffractions in GPR image. In addition, the events at depth of approximately 1-1.25 m in GPR sections must be the metal pipes through which AMD is drained off to the inner bay.

• Journal of Broadcast Engineering
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• v.10 no.4 s.29
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• pp.474-487
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• 2005

T-DMB (Terrestrial-Digital Multimedia Broadcasting) adopted MPEG-4 BIFS (Binary Format for Scene) Core2D scene description profile and graphics profile as the standard of video associated data service. By using BIFS, we can support to overlay objects, i.e. text, stationary image, circle, polygon, etc., on the main display of receiving end according to the properties designated in broadcasting side and to make clickable buttons and website links on desired objects. Therefore, a variety of interactive data services can be served by BIFS. In this paper, we implement real-time video associated data service system far T-DMB. Our developing system places emphasis on real-time data service by user operation and on inter-working and stability with our previously developed video encoder. Our system consists of BIFS Real-time System, Automatic Stream Control System and Receiving Monitoring System. Basic functions of our system are designed to reflect T-DMB programs and characteristics of program production environment as a top priority. Our developed system was used in BIFS trial service via KBS T-DMB, it is supposed to be used in T-DMB main service after improvement process such as intensifying system stability.