• 한국환경복원기술학회지
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• 제9권6호
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• pp.162-167
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• 2006

The urban stream includes the channel and sandbars. The sandbar plays a key role in the riparian ecosystem. For birds and insects the sandbar offers a small strip of habitat and fish and other fauna feed in the boundary of sandbar where eddies occur. So, it is important habitat and source for the flow of energy, matter and organisms through the landscape and act as ecotone between the terrestrial and stream corridors. However, the sandbar changes continuously by the natural process. Thus, it is necessary to measure the shape and area of the sandbar accurately for the efficient urban stream management for the amenity of urban residents and stream protection. The study site is Yangjae Stream where the first natural-style urban stream restoration projected was impelemented by the support of Ministry of Education in Korea. The measurement was taken by the beacon Differential Global Positioning System (DGPS) and the data were stored and analyzed using ArcView Geographic Information System (GIS) program. Therefore, the purpose of this study is to measure the change of sandbars in the urban stream after concentrated stormwater during summer.

• 한국환경보건학회지
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• 제28권2호
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• pp.183-192
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• 2002

Indoor air quality is affected by source strength of pollutants, ventilation rate, decay rate, outdoor level and so on. Although technologies exist to measure these factors directly, direct measurements of all factors are impractical in most field studies. The purpose of this study was to develop an alternative methods to estimate these factors by multiple measurements. Daily indoor and outdoor NO$_2$concentrations for 21 days in 20 houses in summer and winter, Seoul. Using a mass balance model and linear regression analysis, penetration factor (ventilation divided by sum of air exchange rate and deposition constant) and source strength factor(emission rate divided by sum of air exchange rate and deposition constant) were calculated. Subsequently, the ventilation and source strength were estimated. During sampling period, geometric mean of natural ventilation was estimated to be 1.10$\pm$1.53 ACH, assuming a residential NO$_2$decay rate of 0.8 hr$^{-1}$ in summer. In winter, natural ventilation was 0.75$\pm$1.31 ACH. And mean source strengths in summer and winter were 14.8ppb/hr and 22.4ppb/hr, respectively. Although the method showed similar finding previous studies, the study did not measure ACH or the source strength of the house directly. As validation of natural ventilations, infiltrations were measured with $CO_2$tracer gas in 18 houses. Relationship between ventilation and infiltration was statistically correlated (Pearson r=0.63, p=0.02).

• 태양에너지
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• 제7권2호
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• pp.37-53
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• 1987

This study has been prepared for the purpose of developing the system performance prediction method of natural circulation solar hot water system. The storage tank of the natural circulation solar hot water system equipped with flat-plate solar collector is located at higher elevation than the solar collectors. Therefor, the storage tank temperature distribution formed accordance with configuration of storage tank by flow rate of circulating fluid affect system collection efficiency. In this study measure the storage tank temperature distribution with various experimental system under real sun condition and present the theoretical prediction method of the storage tank temperature. Moreover measure the flow rate not only day-time but also night-time reverse flow rate with die injection visual flow meter. Main conclusion obtain from the present study is as follows; 1) The storage tank temperature distribution above the connecting pipe connection position is the same as that of the fully mixed tank and below the connection position is the same as that of stratified tank. 2) The system performance sensitive to the storage tank temperature distribution. Therefore detailed tank model is necessary. Average storage tank temperature can be calculate 3% and storage tank temperature profile can get less than 10% difference with this model system.

• 한국산업융합학회 논문집
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• 제16권1호
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• pp.9-13
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• 2013

This paper measured some condition about differential height of two points for the comparison of measure by direct method and Geodimeter and trigonometric Leveling method. The research was compared relationship between the volue to get from three measure method and five measured man. The significance of between three measure method and five measured man has been investigated by analysis of two-way ANOVA. The result indicate that between five measured man show insignficance, and between the direct method and Geodeter method show signficance and between the direct method and trigonometric Leveling method show signficance but between the Geodeter method and trigonometric Leveling method, two method show insignficant. Therefore, when using Geodemeter leveling method and trigonometric Leveling method, you must keep particular attention when former two Leveling method about instrumental error, natural error, and personal error, two Leveling method using low precision leveling.

• 대한수학회논문집
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• 제30권3호
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• pp.221-226
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• 2015

The natural projection of a parameter lower (upper) distribution set for a self-similar measure on a self-similar set satisfying the open set condition is the cylindrical lower or upper local dimension set for the Legendre self-similarmeasure which is derived from the self-similar measure and the self-similar set.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2006년도 추계학술대회 논문집
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• pp.123-129
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• 2006

The measurement method of natural wind to understand the characteristics of the natural wind along the railway lines in Korea has been investigated to be used in the assessment of the risk of train overturn. The weather information service provided by Korea Meteorological Administration has been employed to outline the broad characteristic of natural wind in Korea. Anemometers using CDMA telecommunication for data transfer have been installed near the railway lines to measure velocities and directions of natural wind and the data processing method has been studied using the measured data.

• The Journal of Asian Finance, Economics and Business
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• 제8권11호
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• pp.145-155
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• 2021

This study examines the export competitiveness of four major natural rubber exporters in the Belt and Road Initiative (BRI) region and investigates the factors affecting bilateral natural rubber export. This study utilized the revealed symmetric comparative advantage (RSCA) to measure export competitiveness. Next, this study employed the gravity model using the Poisson Pseudo Maximum Likelihood (PPML) estimation to analyze the factors affecting bilateral export from the four major natural rubber exporters to 46 countries in the region. The analysis is conducted by using annual data from 2001 till 2018. The findings showed that all four major exporters maintained their export competitiveness. Indonesia and Vietnam notably exhibited increasing trends in the early 2000s. Besides, the market share for Malaysia and Vietnam have increased from 2013 to 2015 with the BRI implementation in 2013. In addition, this study discovered that non-tariff measures (NTM) have a positive and significant impact on the bilateral export of natural rubber. The overall findings strongly indicate that the natural rubber export has increased post BRI announcement. The outcome highlighted the benefits of BRI implementation on the natural rubber export. This study is the first attempt to apply the gravity model on the natural rubber exports within the BRI region.

• Steel and Composite Structures
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• 제32권3호
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• pp.305-312
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• 2019

In this study, we investigated the effect of fatigue crack propagation of the beams which have a vital importance in engineering applications, on the natural frequency of the system. Beams which have a wide range of applications, are used as fundamental structural elements in engineering structures. Therefore, early detection of any damages in these structures is of vital importance for the prevention of possible destructive damages. One of the widely used methods of early detection of damages is the vibration analysis of the structure. Hence, it is of vital importance to detect and monitor any changes in the natural frequencies of the structure. From this standpoint, in this study we experimentally investigated the effect of fatigue crack propagation on beams produced from 4140 steel, of the natural frequency of the beam. A crack was opened on the $8{\times}16{\times}500mm$ beam using a 3 mm long and 0.25 mm wide wire erosion. The beam, then, underwent 3 point bending tests at 10 Hz with a dynamic fatigue device and its natural frequencies were measured in scheduled intervals and any changes taking place on the natural frequencies of the beam were measured. This data allowed us to identify and measure the crack occurring on the beam subjected to dynamic loading, during the propagation phase. This method produced experimental data. The experimental data showed that the natural frequency of the beam decreased with the propagation of the fatigue crack on the beam.

• 한국식품저장유통학회지
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• 제5권1호
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• pp.97-104
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• 1998

The chemical structure of low molecule polyphenol of tea was found as explained. Structure decision of pioanthocyanidin was possible to measure 1,700 molecule, hexamer by chemical basic of polyphenol. At present, structure of high molecule than of that can't be suspected and it is concemed that strong astrigent ccnpound of tea is polymer proanthocyanidin. Mush researches was required in structure decision and isolation of high molecule polyphenol complex. Structure decision will develope at the natural products in the furture.

• 인지과학
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• 제4권1호
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• pp.153-176
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• 1993

구조적 모호성은 자연 언어 문장을 분석할 때 흔히 나타내는 문제점 중의 하나로,지금까지 이문제의 해결은 대단히 어려운 것으로 인식되어 왔다.그러나,구조적 모호성을 해소하지 않고 올바른 언어 처리를 한다는 것은 사실상 불가능하다.본 논문에서는 이 문제에 대하여 정보 이론적(information-theoretic)개념인 상호 정보(mutual information)를 이용한 통계적 접근방법을 제안한다.상호정보는 말 뭉치로 부터 자동 습득이 가능하므로 지식습득속도가 대단히 빠를뿐만 아니라 지속적인 지식습득이 가능하다. 구조적 모호성 해소는 물론 모호성 해소 결과의 옳고 그름을 스스로 판단할수 있는 능력을 부여할수 있다면 보다 지능적인 시스템을 개발하는데 도움이 될것이다.본 논문에서는 그와 같은 지적 능력을 부여한느데 필요한 확신도(congidence measure) 개념도 또한 제시한다.확신도는 구조적 모호성을 해소하고 난 후에 계산되는 수치로서,구조적 모호성이 올바르게 해소되었을 가능성이 높으면 높을수록 그 값이 커지는 성질을 가지고 있다. 본 논문에서 제시한 구조적 모호성 해소 알고리즘의 타당성을 검증하기 위하여 이공계 논문 초록으로부터 발췌된 약 160만 단어의 말뭉치로부터 상호 정보를 자동 습득하고 이를 이용하요,1,639개의 문장에 대하여 구조적 모호성을 해소하는 실험을 하였다. 실험결과 구조적 모호성 해소 정화도는 약 80%로 나타났다.확신도 개념을 이용할 경우 구조적 모호성 해소가 잘못된 문장을 찾아 정정하는 작업을 매우 효과적으로 진행할 수 있었다.