• 한국조사연구학회지:조사연구
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• 제5권1호
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• pp.27-49
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• 2004

최근 한국을 포함한 여러 국가들에 있어 이동전화가 빠르게 보급되면서 유선전화가구보유율이 감소하고 있다. 이러한 유선전화 보유율의 감소로 인하여 표집틀의 중요한 비포함문제가 발생되고 결국 조사 추정치의 편향이 커질 수 있다. 본 논문에서는 먼저 국내에서의 유선전화 가구보유율과 이동전화 가구보유율의 변화를 살펴보고, 사회인구학적 가구 특성에 따른 이들 전화 가구보유율의 변화도 알아본다. 아울러 이로 인한 국내에서의 유선전화 표집틀 비포함 수준의 변화와 문제점들을 언급한다. 다음 유럽연합의 일부 국가들과 미국, 캐나다 등의 최근 유선전화 가구보유율을 비교한다. 마지막으로 국내의 이동전화 증가에 따른 전화조사환경의 변화에 대응하기 위한 앞으로의 연구방향을 제시한다.

• 응용통계연구
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• 제25권6호
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• pp.877-887
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• 2012

The Bank of Korea changed its method of GDP estimation from a fixed-weighted to a chain-weighted measure in 2009. The fixed-weighted method had had problems such as substitution bias and the rewriting of economic history. As a result of the change, annual growth rates calculated using the chain-weighted method from 1970 through 2008 turned out to be 0.8%p higher on average than the existing rates. The quarterly average chain-weighted growth rates were 0.19%p higher than the fixed-weighted ones, but they changed in the same directions. In this paper we analyze whether the differences in rates between the two calculation methods would bring about a difference in the cyclical characteristics of GDP. We conclude that although there were differences in growth rates after introduction of the chain-weighted method, there was no difference in the cyclical fluctuation.

• Environmental Engineering Research
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• 제14권4호
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• pp.238-242
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• 2009

This study investigated the effects of organic loading rates on simultaneous carbon and nitrogen removal in an innovative fixed-film aerobic bioreactor. The fixed-film bioreactor (FFB) was composed of a two-compartment aeration tank, in which a synthetic filamentous carrier was submerged as biofilm support media, and a settling tank which polyvinylidene media (Saran) was used as settling aid for suspended solids. Three different organic loading rates, ranging from 0.92-2.02 kg chemical oxygen demand/$m^3$/day were applied by varying hydraulic retention time (HRT). The total soluble organic carbon removal efficiencies were in the range of 90-97%. The removal efficiency of ammonia was found to be in the range of 70-84%. Total nitrogen removal efficiency was found to be in the range of 40-45%, which indicates that denitrification reactions occurred simultaneously in the attached biofilm on the fibrous media in the aeration tank. The settling performance of suspended solids was significantly improved due to the presence of Saran media in the settling compartment, even for a short HRT. The fixed-film aerobic bioreactor used in this study demonstrated efficient treatment efficiency even at higher organic loading rates and at short HRTs.

• 한국조사연구학회:학술대회논문집
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• 한국조사연구학회 2002년도 추계학술대회 발표논문집
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• pp.241-253
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• 2002

1980년대 이후 전 세계적으로 유선 전화가 빠르게 보급되고 다양한 표본 추출 기법들이 개발되면서 자료 수집 방법으로서 전화 조사가 널리 사용되어 왔다. 한편 1990년대 초반 이후 통신기술이 급격히 발전하면서 대부분의 국가에서 핸드폰의 수가 점차적으로 증가했고 특히 최근 수년간에 걸쳐 그 수가 급증했다. 아울러 유선 전화 대신 핸드폰만을 소유하는 전화 가구들이 증가하면서 많은 국가들에 있어 유선 전화 가구 보급률이 감소하고 있다. 본 논문에서는 유럽 연합, 우리나라를 포함한 아시아 지역, 북미 등에서 핸드폰의 증가에 따른 유선 전화 가구 보급률의 변화와 동향을 살펴보고 특히 우리나라에서도 당면할 수 있는 전화 조사상편의 문제를 다룬다.

• 한국연소학회:학술대회논문집
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• 한국연소학회 2014년도 제49회 KOSCO SYMPOSIUM 초록집
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• pp.29-32
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• 2014

The practical route for disposal of sewage sludge becomes energy recovery by combustion after its ocean dumping is banned in 2012 in Korea. Due to the high moisture content, however, sewage sludge is required to be dried before transport and combustion. In this study, pyrolysis and combustion characteristics of dried sewage sludge was investigated in a small-scale fixed bed reactor in order to provide fundamental data for energy recovery of the fuel. As the first step of combustion, the primary products of pyrolysis were analyzed in a fixed bed reactor for the condensable volatiles (tar), non-condensable gases, and char. For the combustion characteristics, another fixed bed reactor was constructed to monitor the weight and temperature of the fuel particles during ignition and combustion under different air flow rates. The test results were used to derive the ignition and burning rates.

• 한국농업기계학회:학술대회논문집
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• 한국농업기계학회 1993년도 Proceedings of International Conference for Agricultural Machinery and Process Engineering
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• pp.666-675
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• 1993

In order to prevent bodily injuries frequently suffered in using bush cutters, especially from spattered stones, we developed a unique new cutting system equipped with a fixed blade on top of the rotary blade, and checked into the mowing performance of the cutter. From experimental test of mowing efficiency and measuring test of physical stress (O$_2$ consumption and heartbeat rates) , the new cutting system with a fixed blade proved that it keeps good cutting performance with lower peripheral speed of the rotary blade(22m/sec), compared to that of ordinary cutting blade, yielding more safety in operation. Weight of the cutter head is, however, heavier than that of ordinary machine by about 70% which increased a physical stress on the operator with slightly faster heartbeat rates. In mowing along edge of concrete wall, the operator enjoyed using the cutter with no anxiety , owing to function of the fixed blade.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2008년도 추계학술대회A
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• pp.1896-1901
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• 2008

Single crystalline copper nanowires are subjected to bending tests using molecular dynamics simulations and the embedded atom method. To observe behaviors of nanowire, bending tests are performed for various rates of deflection and different boundary conditions: fixed-free and fixed-fixed. When the deflection of nanowire becomes large, twinnings and dislocations appear, and <100> crystal structure transforms to <110>. At high rates, phase transformation occurs in whole nanowire. But, at low rates, atomic structure changes to <110> phase partially. The final deformed structures are affected by the rate of deflection and boundary conditions. These effects can be important design parameters at nanoscale.

• 노동경제논집
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• 제31권3호
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• pp.21-46
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• 2008

본 논문은 산업재해에 대하 예방을 강화하기 위해, 산업재해율이 상대적으로 높은 50인 미만 영세 제조업체를 중심으로 2001년 이후 보조금을 지급한 클린사업장 조성사업의 순수한 산재 감소효과를 추정하기 위해 작성되었다. 본고의 분석 결과에 따라 가장 신뢰도가 높은 추정방법인 (1) 선택 편의를 통제하기 위하여 클린사업장 1년 전의 자료를 제외하고 (2) 고유 효과(fixed effect) 차분모형을 이용한 회귀분석을 사용한 결과를 중심으로 분석한 결과 클린사업장으로 인정된 사업장의 인정 이전 산재발생률이 0.34%포인트 정도 하락하는 것으로 추정되었음을 감안할 때 산재발생률에서는 15.8% 감소한 것으로 보아야 할 것이다.

• The Journal of the Acoustical Society of Korea
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• 제16권3E호
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• pp.44-49
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• 1997

In this paper, we propose an adaptive encoding method of fixed codebook in CELP coders and implement an adaptive fixed code exited linear prediction(AF-CELP) speech coder. AF-CELP exploits the fact that the fixed codebook contribution to speech signal is also periodic like the adaptive codebook (or pitch filter) contribution. By modeling the fixed code book with the pitch lag and the gain from the adaptive codebook, AF-CELP can be implemented at low bit rates as well as low complexity. Listening tests show that a 6.4 kbit/s AF-CELP has a comparable quality to the 8 kbit/s CS-ACELP in background noise conditions.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2002년도 ITC-CSCC -1
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• pp.552-555
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• 2002

Wideband CDMA is one of the radio access technologies for the third generation in which voice is the basic service. There has been lot of research work in order to find out the suitable transmission scheme to meet the requirement of accommodating variable type of services in Wideband-CDMA. This paper studies the behavior of different services using different transmission schemes in Wideband CDU and compares their performance in terms of BER. Different transmission schemes are found to be suitable for different services. Transmission schemes used are- fixed processing gain scheme also called as variable bandwidth scheme, single code transmission and multicode transmission. It is found that fixed processing gain scheme is suitable fur high data rates. Single code transmission is suitable fer low data rates where as multicode transmission is suitable for low and medium data rates.