• 한국해안해양공학회지
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• 제14권1호
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• pp.34-40
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• 2002

본 연구에서는 해안선 부근의 장주기파가 해안침식과 관련이 있음에 주목하며 심해파의 특성으로부터 천해역의 장주기파의 파고를 추정하기 위해 파고계 3대를 해안으로부터 외해방향의 해안종단 방향으로 일직선상에 배치하여 현장관측을 실시하고 그 결과를 분석하였다. 아울러, 장주기파의 발생기구에 관한 기존의 이론을 현장관측을 통해 검증하고, 장주기파의 발생기구를 토대로 심해파 제원과 천해역의 장주기 파고와의 관계를 검토하였다. 관측된 장주기파는 기존의 이론과 대체적으로 일치하였으며, 심해파와 장주기파 사이에는 선형적인 대응이있음을 확인하였다. 또한, 장주기파의 공간적·시간적 변화를 추가하기 위하여 각 지점별로 관측된 장주기파를 합성함으로서 장주기파의 파고를 계산하였다. 그 결과, 장주기파와 심해파 사이의 관계는 더욱 뚜렷한 경향을 나타내었으며, 양자로부터 장주기파의 추정식을 도출할 수 있었다. 따라서, 이를 이용함으로서 해당지역의 천해역에 존재하는 장주기파랑의 규모가 심해파랑의 자료로부터 예견될 수 있을 것으로 사료된다.

• Ocean and Polar Research
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• 제27권2호
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• pp.189-195
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• 2005

Several models predict large and potentially abrupt ocean circulation changes due to anthropogenic greenhouse-gas emissions. These circulation changes drive-in the models-considerable oceanic oxygen trend. A sound estimate of the observed oxygen trends can hence be a powerful tool to constrain predictions of future changes in oceanic deepwater formation, heat and carbon dioxide uptake. Estimating decadal scale oxygen trends is, however, a nontrivial task and previous studies have come to contradicting conclusions. One key potential problem is that changes in the historical observation network might introduce considerable errors. Here we estimate the likely magnitude of these errors for a subset of the available observations in the Southern Ocean. We test three common data analysis methods south of Australia and focus on the decadal-scale trends between the 1970's and the 1990's. Specifically, we estimate errors due to sparsely sampled observations using a known signal (the time invariant, temporally averaged, World Ocean Atlas 2001) as a negative control. The crossover analysis and the objective analysis methods are for less prone to spatial sampling location biases than the area averaging method. Subject to numerous caveats, we find that errors due to sparse sampling for the area averaging method are on the order of several micro-moles $kg^{-1}$. for the crossover and the objective analysis method, these errors are much smaller. For the analyzed example, the biases due to changes in the spatial design of the historical observation network are relatively small compared to the tends predicted by many model simulations. This raises the possibility to use historic oxygen trends to constrain model simulations, even in sparsely sampled ocean basins.

• 한국수자원학회:학술대회논문집
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• 한국수자원학회 2022년도 학술발표회
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• pp.334-334
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• 2022

Improvement of old-fashioned rain gauge systems for automatic, timely, continuous, and accurate precipitation observation is highly essential for weather/climate prediction and natural hazards early warning, since the occurrence frequency and intensity of heavy and extreme precipitation events (especially floods) are recently getting more increase and severe worldwide due to climate change. Although rain gauge accuracy of 0.1 mm is recommended by the World Meteorological Organization (WMO), the traditional rain gauges in both weighting and tipping bucket types are often unable to meet that demand due to several existing technical limitations together with higher production and maintenance costs. Therefore, we aim to introduce a newly developed and cost-effective hybrid rain gauge system at 0.1 mm accuracy that combines advantages of weighting and tipping bucket types for continuous, automatic, and accurate precipitation observation, where the errors from long-term load cells and external environmental sources (e.g., winds) can be removed via an automatic drainage system and artificial intelligence-based data quality control procedure. Our rain gauge system consists of an instrument unit for measuring precipitation, a communication unit for transmitting and receiving measured precipitation signals, and a database unit for storing, processing, and analyzing precipitation data. This newly developed rain gauge was designed according to the weather instrument criteria, where precipitation amounts filled into the tipping bucket are measured considering the receiver's diameter, the maximum measurement of precipitation, drainage time, and the conductivity marking. Moreover, it is also designed to transmit the measured precipitation data stored in the PCB through RS232, RS485, and TCP/IP, together with connecting to the data logger to enable data collection and analysis based on user needs. Preliminary results from a comparison with an existing 1.0-mm tipping bucket rain gauge indicated that our developed rain gauge has an excellent performance in continuous precipitation observation with higher measurement accuracy, more correct precipitation days observed (120 days), and a lower error of roughly 27 mm occurred during the measurement period.

• 한국기후변화학회지
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• 제2권2호
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• pp.133-141
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• 2011

본 연구에서는 약 100년 기상 관측 자료가 축적된 강릉의 기온과 강수량 자료를 중심으로 기후변화 추세를 분석하여, 강원 지방의 기후변화 경향을 파악하고자 하였다. 지난 98년(1912~2009년)간 강릉의 연평균 기온은 $1.4^{\circ}C$ 상승하였으며, 연강수량은 14.7% 증가하였다. 강수일수는 감소하였고, 강수량은 증가하여 결과적으로 강수강도가 증가하였다. 기온 자료를 기준으로 정의된 자연계절의 변화를 보면 봄과 여름의 시작일이 빨라졌고, 가을과 겨울의 시작일은 늦어졌다. 또한, 여름은 한 달 정도 길어졌고, 겨울은 한 달 가량 짧아졌다. 강원도 7개 기상 관측 자료를 평균한 강원 지역의 연평균 기온은 지난 37년(1973~2009년) 동안 $0.8^{\circ}C$ 상승하였고, 연평균 강수량은 21% 증가하였다. 지역별로 살펴보면 연평균 기온의 경우 원주에서 $1.6^{\circ}C$로 가장 높은 상승 추세를 보였고, 속초에서 $0.4^{\circ}C$로 가장 낮은 상승 추세를 나타냈다. 연강수량의 변화 추세는 대관령에서 22.2%로 가장 높게 나타났고, 원주가 12.0%로 가장 낮았다.

• 한국농림기상학회지
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• 제23권4호
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• pp.405-414
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• 2021

본 연구에서는 30년(1991-2020)에 대한 PNU CGCM-WRF chain에서 생산된 6개월 과거예측 자료를 이용하여 남한 전역에 대한 찰옥수수 수확일을 추정하고 평가하였다. 찰옥수수 수확일을 추정하기 위해 61개 지점의 기온 관측 자료와 모형의 기온 예측 자료를 파종일부터 수확 기준 온도까지 적산하는 적산온도 방법을 이용하였다. 평균 기온의 경우, 모형예측 자료는 분석기간(4~9월)에 대해 관측과 비교하여 약 2.9℃도 정도 기온을 과소모의하였다. 이러한 모형의 기온 오차가 적산온도에 반영되어, 관측으로 추정한 수확일과 비교하여 모형은 약 14.4~16.9일 늦게 찰옥수수 수확일을 모의하였다. 오차가 개선된 모형 결과는 기온 예측 자료의 평균 오차가 0.1℃로 감소되고, 수확일 지연이 약 1.1~1.3일로 감소되어 정량적으로 관측과 유사하게 모의하였다. 따라서, 본 연구에서는 PNU CGCM-WRF chain의 미래 기온 예측자료에 적산온도 생육추정 방법을 적용하여 찰옥수수 수확일을 추정함으로써 기후예측자료의 농업부문 활용성을 확인하였다. 찰옥수수와 같이 적산온도가 생육에 큰 영향을 미치는 작물의 경우, 본 연구에서 사용된 방법에 적합한 파종시기와 적산온도 기준값을 설정한다면 다양한 작물에 대한 생육시기 정보를 6개월 사전에 예측하고 활용할 수 있을 것으로 생각된다.

• 한국초등과학교육학회지:초등과학교육
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• 제22권1호
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• pp.109-120
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• 2003

The purpose of this study is to observe, to analyze of the preservice teachers' naive theories about the change of season. And it is to find a instruction strategy which can solve problem about this. The general idea about the change of season is observed by the 3 methods which are simply explaining with words, explaining with pictures and models. The author is to find the similarity. difference and relationship which the preservice teachers have about the general idea about the change of season. The important changable primary factors, which can effect to the general Idea formation, are naturally dragged out through the observation of preservice teachers participation. For this study, 4 first year preservice teachers of one of national university of education are used. Before the interview. the author tries to form rapport with the preservice teachers. Experiment materials, pencil. paper, camcorder, digital recorder and interview note were used for the study with reflection of them just way they are. As the result of the interview. all of 4 preservice teachers had not being understand the concept about the change of season and the three ways of explanation methods were not matched each other, so it is revealed that the general Idea of the change of season, which the preservice teachers have, is not strongly formed. In spite of the repeated study of the change of season from elementary school to university, it has many problem about recognition of the general idea about the change of season which pre-elementary teachers have. Therefore it is needed to improve the experiment in elementary science text book and naive theories by the activity which is explaining the change of season in three dimension space. to prevent the naive theories which the preservice teachers may have.

• 한국지구과학회지
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• 제30권2호
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• pp.185-195
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• 2009

이 연구의 목적은 삼림파괴로 유발되는 몇 가지 기상학적 요소의 변화를 관측을 통해서 조사하였다. 이 연구를 위해서 기상관측 장치를 숲이 파괴된 곳과 숲이 보존되어 있는 곳에 설치하여 1년간(2006. 12.-2007. 12) 연속 관측하였다. 이 후로 숲이 파괴된 지점을 point 1 그리고 숲이 보존되어 있는 지점을 point 2라고 지칭하기로 한다. 이 연구에서는 여름철에 강우가 있은 다음 날부터 1주일 동안 관측된 두 지역의 자료를 비교 분석하였다. 관측 자료의 분석을 통하여 야간에는 두 지역의 온도분포가 비슷하였지만, 낮에는 지점 1에서 관측된 기온이 지점 2보다 약 $1.5^{\circ}C$ 높게 나타났다는 것을 확인할 수 있었다. 하지만 야간에는 두 지점간의 차이가 작았다. 상대습도도 숲의 보존지역(지점2)에서 높게 나타났는데, 그 차이는 한낮에 10%정도에 이르렀다. 지표와 지중 15cm 깊이의 온도도 두 지역 사이에 큰 차이를 보였다. 그 차는 낮에 크고 야간에는 작았는데, 대체로 지점 1에서의 값이 $3-10^{\circ}C$ 더 높게 나타났다. 토양수분은 지점에서 7.1%, 지점 2에서 19.5%로 나타나서 지점 2에서의 토양 수분이 지점 1보다 훨씬 높았다. 두 지점에서 풍향은 주로 북서-북동풍으로 거의 차이가 없었지만, 풍속은 지점 2(0.3m/s)에서 지점 1(0.5m/s)보다 작게 관측되었다. 이러한 관측 자료를 바탕으로 두 지점 사이에 존재하는 열수지적 차이에 대해서도 분석하였다.

• 열처리공학회지
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• 제4권3호
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• pp.54-62
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• 1991

The effect of tempering temperature on the ultrasonic propagation velocity at SCM 440 steel quenched from $870^{\circ}C$ and $1000^{\circ}C$ has been studied by metallurgical and crystallographical observation. The measurements of ultrasonic velocity were made on the specimen by appling an immersion ultrasonic pulse-echo technique with a constant frequency of 10 MHz. The quenched microstructure of this steel was a lath martensite. As the tempering temperature was increased, the martensite was transformed into the tempered martensite composed of cementite and carbide. The ultrasonic velocity increased with increasing the tempering temperature. It was thought that these were resulted from the microstructural transformation. The change of ultrasonic propagation velocity with quenching and tempering heat treatment was resulted from microstrain due to the change of internal stress. Considering these results concerning to the change of ultrasonic propagation velocity. the phenomena of microstructural transformation were estimated. Consequently, it was thought that the degree of quenching and tempered heat treatment of steel could be nondestructively evaluated with the change of ultrasonic propagation velocity.

• 대한지구과학교육학회지
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• 제5권3호
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• pp.307-315
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• 2012

The purpose of this study was to examine the effects of small inquiry method on space perception ability and creative personality. Testees of this research are 36 elementary pre-service teachers taking an astronomical observation class. Doing inquiry activity after 36 elementary pre-service teachers are classified into 6 Jigsaw small inquiry. Learning activity was split into two groups, expert group and a population. To find out research outcome, pre-test was executed space perception ability test, creative personality test. Analysis of test result was accomplished with statistical package SPSS 18.0 paired t testing hypothesis. The results of this study are as follows. First, 'source of season change' class using Jigsaw small inquiry method has effect on space perception ability improvement. This was interpreted that space perception ability improvement was effective because characteristic of Jigsaw small inquiry is made up of lots of semin Second, 'source of season change' class using Jigsaw small inquiry method has no effect on creative personality. This was interpreted that experiment and discussion activity getting accomplished in a short time has no effect on qualitative characterizing Creative Personality improvement.

• International Journal of Air-Conditioning and Refrigeration
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• 제16권1호
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• pp.22-29
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• 2008

A sequence of visually experimental observations was conducted to investigate the flow boiling and two-phase flow in a coiled tube. Different boiling modes and bubble dynamical evolutions were identified for better recognizing the phenomena and understanding the two-phase flow evolution and heat transfer mechanisms. The dissolved gases and remained vapor would serve as foreign nucleation sites, and together with the effect of buoyancy, centrifugal force and liquid flow, these also induce very different flow boiling nucleation, boiling modes, bubble dynamical behavior, and further the boiling heat transfer performance. Bubbly flow, plug flow, slug flow, stratified/wavy flow and annular flow were observed during the boiling process in the coiled tube. Particularly the effects of flow reconstructing and thermal non-equilibrium release in the bends were noted and discussed with the physical understanding. Coupled with the effects of the buoyancy, centrifugal force and inertia or momentum ratio of the two fluids, the flow reconstructing and thermal non-equilibrium release effects have critical importance for flow pattern in the bends and flow evolution in next straight sections.