• Journal of the Korean Data and Information Science Society
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• v.11 no.2
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• pp.279-293
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• 2000

This article suggests two change-point estimators which are modifications of Carlstein(1988) change-point estimators with rank functions and mean functions where there is one change-point in a mean function. A comparison study of Carlstein(1988) estimators and proposed estimators is done by simulation on the mean, the MSE, and the proportion of matching true change-point.

• Proceedings of the Acoustical Society of Korea Conference
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• 1998.06c
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• pp.221-224
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• 1998

간섭신호가 원하는 신호에 coherent한 경우에는 원하는 신호와 간섭신호간의 cross correlation에 의해 공분산 행렬의 rank가 줄어들게 되어 coherent한 간섭신호의 도래각을 추정할 수 없게 된다. 이러한 문제를 해결하기 위해 발표된 기존의 방법중 대칭 어레이(Symmetric array)방법은 계산량이 많아지고 공간 스무딩(Spatial Smoothing)방법은 array aperture size에서 손해를 보게 되어 분해능이 떨어지는 단점이 있다[1,2,3].

• Journal of Korean Society of Forest Science
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• v.60 no.1
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• pp.24-29
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• 1983

This study was carried out to compare the diameter increment of seven major selected tree species which grow wild in middle area of Korea. The results obtained were summarized as follows. 1) The difference in annual diameter increment among seven species according to D.B.H. classes showed to be the strongest in Juglang mandshurica, the second rank Corpus controversa, the third rank Betula platyphylla, the fourth rank Tilia amurensis, the second rank Fraxinus mendshurica, the sixth rank Populus davidiana, and the weakest in Ulmus davidiana. 2) Total diameter increment among seven species according to tree age classes were ranked as follows: Juglans mandshurica, Cornus controversa, Betula platyphylla, Tilia amurensis, Fraxinus mandshurica, Populus davidiana, and Ulmus davidiana. 3) Juglans mandshurica showed the highest diameter increment in comparison with other six species, while diameter increment in Ulmus davidiana and Populus davidiana decreased in earlier age than other species.

• Journal of Korea Technology Innovation Society
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• v.15 no.1
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• pp.28-46
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• 2012

This paper proposes the science and technology policy implications of power law in econophysics methodology under the recent convergence technology environment. Empirical results are summarized as follow: first, similar empirical results are showed up using Hill estimates and Rank-1/2 estimates in patent data set during 1990 through 2008. Second, the estimates of power law exponents for technology capability distribution are decreased during the periods. The policy implications for science and technology development draw from the empirical results. First, the fact that the exponents of power law are decreased show the convergence of technology capability among countries. The our country policy directs focus on the innovation strategy rather than imitation strategy. Second, the volatility of technology change results from a few capable technology developers so that policy direct may need to control the technology power in the large technology developer or company. The methodology and analytical results used in the paper may also be useful for consider for the science and technology phenomena such as convergence and divergence of technologies among countries in the world.

• Journal of Korean Society of Forest Science
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• v.68 no.1
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• pp.52-59
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• 1985

This study was carried out to compare the diameter increment of Pinus densiflora for.erecta, Pinus koraiensis, Larix leptolepis, Abies holophylla and Abies koreana growing in middle area of Korea. The results obtained were summarized as follows; 1) The difference in annual diameter increment among five species according to D.B.H classes showed to be the strongest in Pinus koraiensis the second rank Larix leptolepis, the third rank Pinus densiflora erecta, the fourth rank Abies holophylla and the weakest in Abies koreana. 2) It was inferred that when the D.B.H of Pinus densiflora for.erecta comes to 95cm, Pinus koraiensis 80cm, Larix leptolepis 80cm, Abies holophylla 140cm and Abies koreana 85cm respectively, their diameter do not increase. 3) Total D.B.H increment among five species according to tree age classes were ranked as follows; Larix leptolepis, Pinus koraiensis, Pinus derasiflora for.erecta, Abies holophylla and Abies koreana. 4) It was inferred that when the age of Pinus densiflora for.erecta comes to 200yrs, Pinus koraiensis 120yrs, Larix leptolepis 120yrs, Abies holophylla 260yrs and Abies koreana 300yrs respectively, their diameter do not increase. 5) Abies koreana showed the lowest diameter increment in comparison with other four species, while diameter increment in Abies holophylla and Abies koreana decreased in later age than other species.

• Journal of Energy Engineering
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• v.6 no.2
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• pp.176-187
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• 1997

As a way to evaluate the performance of IGCC (Integrated Gasification Combined Cycle) processes, heating values of coal gas as well as plant efficiency were compared for different rank coals and coal feeding methods by employing the static process simulation technique. Performance of the process was compared with coal rank that was varied by three assorted bituminous coals and also by three subbituminous coals, in addition to the two types of feeding techniques, i.e., dry-feeding and slurry-feeding, that are utilized in entrained-bed coal gasifiers. For the verification of the simulation technique, simulated results were compared first with the actual pilot plant data published from Shell and Texaco. The simulation technique was, then, applied to other coals. Result from tests varying coal rank exhibits the trend of improving both heating content of the product gas and plant efficiency with increasing carbon content in coal. The effect of coal rank is more sensitive in slurry-feeding cases compared to the dry-feeding cases. In particular, considering notably lower values in gas heating value and plant efficiency calculated in the slurry-feeding case that uses a subbituminous coal, limited utilization of the slurry-feeding method for subbituminous coals can be expected. From the plant efficiency point of view, dry-feeding method resulted in higher simulated efficiency values by maximum 3% for subbituminous coals and ca. l% for bituminous coals.

• Journal of Korea Water Resources Association
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• v.48 no.6
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• pp.491-500
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• 2015

In order to improve the runoff estimation accuracy of the Natural Resources Conservation Service (NRCS) curve number (CN) model, this study incorporated rainfall and maximum potential retention as contributors for initial abstraction. The modification was proposed based on 658 rank-order data of rainfall and subsequent runoff from 15 watersheds. The NRCS-CN model (M1), one of its inspired modified model (M2), and the proposed model (M3) were analyzed employing different CN approaches. Using tabulated, calculated and least squares fitted CNs ($CN_T$, $CN_C$, $CN_{LSF}$, respectively), the models' performances were evaluated based on Root Mean Square Error (RMSE), Nash-Sutcliffe Efficiency (NSE), and Percent Bias (PBIAS). Applications of model M1, M2, and M3, respectively exhibited watershed cumulative mean [RMSE (23.60, 18.12, 16.04), NSE (0.54, 0.73, 0.79), and PBIAS (36.54, 20.25, 12.00)]. Similarly, using CNC (for M1 and M2 model) and $CN_{LSF}$ (for M3 model), the performance of three models respectively were assessed based on watershed cumulative mean [RMSE (17.17, 15.88, 13.82), NSE (0.76, 0.80, 0.85), and PBIAS (3.06, 4.47, 0.11)]. The proposed model (M3) that linked all of the NRCS-CN variants showed more statistically significant agreement between the observed and estimated data.

• Journal of Animal Science and Technology
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• v.55 no.3
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• pp.173-178
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• 2013

The characteristics of lactation persistency was investigated for new evaluation trait using 4,366,900 milk yield records from 436,690 heads of Korean Holstein dairy cattle. The average lactation persistencies of first parity, second parity and over third parity were 97.5%, 95.1% and 94.6%, respectively and there was a trend that after the peak yield, lactation persistency decreased collectively. The average days of peak milk yields after calving was about 50 days, but only 33.2% of cows reached peak yields at 36~66 days (second test day). Also, there was a difference between the milk yield of cows which reached peak yields at first test day by lactation days and that of cows which reached peak yields at second to fourth test day. The estimates of heritabilty and repeatability for mean lactation persistency were 0.16 and 0.35, respectively. The genetic correlation between cumulative lactation persistency from third to tenth test day and that from third to seventh test day was 0.91 and while it increased in later test day, it decreased sharply in earlier test day. The breeding value correlations of Data II and III for Data I were 0.80 and 0.72, respectively, while the rank correlations were 0.78 and 0.71, respectively. Based on the results, the breeding value and rank correlations decreased when more data were added.

• Journal of Korean Society of Transportation
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• v.34 no.5
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• pp.437-448
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• 2016

Some previous researches suggested a transit trip destination inference method by constructing trip chains with incomplete(missing destination) smart card dataset obtained on the entry fare control systems. To explore the feasibility of the transit trip destination inference method, the transit trip chains are constructed from the pre-paid smart card tagging data collected in Busan on October 2014 weekdays by tracing the card IDs, tagging times(boarding, alighting, transfer), and the trip linking distances between two consecutive transit trips in a daily sequences. Assuming that most trips in the transit trip chains are linked successively, the individual transit trip destination zones are inferred as the consecutive linking trip's origin zones. Applying the model to the complete trips with observed OD reveals that about 82% of the inferred trip destinations are the same as those of the observed trip destinations and the inference error defined as the difference in distance between the inferred and observed alighting stops is minimized when the trip linking distance is less than or equal to 0.5km. When applying the model to the incomplete trips with missing destinations, the overall destination missing rate decreases from 71.40% to 21.74% and approximately 77% of the destination missing trips are the single transit trips for which the destinations can not be inferable. In addition, the model remarkably reduces the destination missing rate of the multiple incomplete transit trips from 69.56% to 6.27%. Spearman's rank correlation and Chi-squared goodness-of-fit tests showed that the ranks for transit trips of each zone are not significantly affected by the inferred trips, but the transit trip distributions only using small complete trips are significantly different from those using complete and inferred trips. Therefore, it is concluded that the model should be applicable to derive a realistic transit trip patterns in cities with the incomplete smart card data.

• Korean Journal of Agricultural and Forest Meteorology
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• v.18 no.4
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• pp.348-356
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• 2016

Carbon dioxide ($CO_2$) gases concentration in atmosphere has been growing since preindustrial times. By sequestering a large amount of atmospheric carbon (C), terrestrial ecosystems are thought to offer a mitigation strategy for reducing global warming. Woody agro-ecosystems such as fruit tree are among the least quantified and most uncertain elements in the terrestrial carbon cycle. $CO_2$ and energy fluxes were measured by the eddy covariance method on a 15-year old apple orchard of South Korea in 2006. Environmental parameters (net radiation, precipitation, etc.) were measured along with fluxes. The results showed that during late June, the ability to sequestrate C was significant at an apple orchard ecosystem and it reached on the peak of $-6.5g\;C\;m^{-2}\;d^{-1}$. We found that in the apple orchard, the daily average of net ecosystem exchange of $CO_2$ (NEE) and cumulative NEE on a yearly basis were $-1.1g\;C\;m^{-2}$ and $-396.9g\;C\;m^{-2}$, respectively. These results reveal that there is high carbon sequestration in the apple orchard of South Korea, which is the same magnitude with repect to that of a natural forested ecosystem of the same biome rank (temperate-humid deciduous forest).