• 한국항공우주학회지
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• 제48권11호
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• pp.927-933
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• 2020

본 논문에서는 항공기 자세 변화를 고려한 항공기 보조연료탱크 연료량측정시스템을 제시하였다. 개발된 연료량측정시스템은 연료센서, 데이터 처리장치, 계기 및 센서 데이터로부터 연료량을 추정하는 소프트웨어로 구성되었다. 지상에서의 롤 및 피치 자세 변화를 모사하기 위해 모사시험 장치가 개발되었다. 모사시험장치를 이용하여 다양한 연료량, 롤 및 피치 각도의 센서 데이터를 자동으로 측정하여 트레이닝 데이터 세트를 획득하였다. 연료량을 추정하는 연료량 측정 소프트웨어를 트레이닝 데이터 세트와 함께 삼선형보간법을 사용하여 개발하였다. 개발된 연료량측정시스템은 참값을 알고 있는 테스트 데이터 세트의 연료 추정 오차를 측정하여 검증하였다. 테스트를 통해 개발된 연료량측정시스템의 오차가 TSO-C55 문서의 기준을 충족하는 것을 확인하였다.

• Journal of Radiation Protection and Research
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• 제46권4호
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• pp.204-212
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• 2021

Background: Identification of radioisotopes for plastic scintillation detectors is challenging because their spectra have poor energy resolutions and lack photo peaks. To overcome this weakness, many researchers have conducted radioisotope identification studies using machine learning algorithms; however, the effect of data normalization on radioisotope identification has not been addressed yet. Furthermore, studies on machine learning-based radioisotope identifiers for plastic scintillation detectors are limited. Materials and Methods: In this study, machine learning-based radioisotope identifiers were implemented, and their performances according to data normalization methods were compared. Eight classes of radioisotopes consisting of combinations of ²²Na, ⁶⁰Co, and ¹³⁷Cs, and the background, were defined. The training set was generated by the random sampling technique based on probabilistic density functions acquired by experiments and simulations, and test set was acquired by experiments. Support vector machine (SVM), artificial neural network (ANN), and convolutional neural network (CNN) were implemented as radioisotope identifiers with six data normalization methods, and trained using the generated training set. Results and Discussion: The implemented identifiers were evaluated by test sets acquired by experiments with and without gain shifts to confirm the robustness of the identifiers against the gain shift effect. Among the three machine learning-based radioisotope identifiers, prediction accuracy followed the order SVM > ANN > CNN, while the training time followed the order SVM > ANN > CNN. Conclusion: The prediction accuracy for the combined test sets was highest with the SVM. The CNN exhibited a minimum variation in prediction accuracy for each class, even though it had the lowest prediction accuracy for the combined test sets among three identifiers. The SVM exhibited the highest prediction accuracy for the combined test sets, and its training time was the shortest among three identifiers.

• 한국지열·수열에너지학회논문집
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• 제10권2호
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• pp.7-12
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• 2014

Government has recently restricted heating and cooling set temperatures for the commercial and public buildings due to increasing national energy consumption. The goal of this paper is to visualize a future two way indoor set temperature control impact on building energy consumption by using TRNSYS simulation modeling. The building was modelled based on the twin test cell with the same dimension. Air source ground coupled heat pump performance data has been used for modeling by TRNSYS 17. Daejeon weather data has been used from Korea Solar Energy Society. The heating set temperature in the reference room is $24^{\circ}C$ as well as the target room set temperature are $23^{\circ}C$, $22^{\circ}C$, $21^{\circ}C$ and $20^{\circ}C$. The cooling set temperature of the reference room is also $24^{\circ}C$ as well as the target room set temperature of $25^{\circ}C$, $26^{\circ}C$, $27^{\circ}C$ and $28^{\circ}C$. For the air source heat pump system, heating season energy consumption is $35.52kWh/m^2y$ in the reference room. But the heating energy consumption in the target room is reduced to 7.5% whenever the set temperature decreased every $1^{\circ}C$. The cooling energy consumption in the reference room is $4.57kWh/m^2y$. On the other hand, the energy consumption in the target room is reduced to 22% whenever the set temperature increased every $1^{\circ}C$ by two way controller. For the geothermal heat pump system, heating energy consumption in the reference room is reduced to 20.7%. The target room heating energy consumption is reduced to 32.6% when the set temperature is $22^{\circ}C$. The energy consumption in the target room is reduced to 59.5% when the set temperature is $26^{\circ}C$.

• 한국농림기상학회지
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• 제22권4호
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• pp.239-249
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• 2020

본 연구는 자연 조건에서 쌀가루용 벼의 수발아율을 예측하기 위한 것으로 기계학습을 이용하여 기상요소들에 따른 수발아율을 간단히 예측할 수 있는 초기 시스템을 개발하기 위해 수행되었다. 이를 위하여 강원도, 충청북도, 경상북도에 위치한 6개 지역에서 쌀가루용 벼 3품종을 재배하였다. 수확 후 수발아율과 출수일을 조사하였으며, 각 지역의 종관기상대의 일평균 기온과 상대 습도, 그리고 강수량 정보를 이용하여 기계학습 모델 중 하나이며, 정확도가 높은 GBM 모델로 수발아율을 예측하였다. 2017년부터 2019년까지 강원과 충북, 그리고 경북의 6개 지역에서 쌀가루 용 벼 3품종에 대해 재배 실험을 수행하였다. 조사 항목은 출수일과 수발아율이었다. 기상자료는 동일한 지역명의 종관기상대를 이용하여 일 평균 기온 및 상대 습도, 그리고 강수량 자료를 수집하였다. 수발아율 예측을 위해 기계학습 모델인 Gradient Boosting Machine (GBM)을 이용하였으며, 학습 투입 변수로는 평균 기온과 상대 습도, 그리고 총 강수량이었다. 또한 수발아 피해 관련 기간을 설정하기 위해 출수 후 몇일 후부터 그 이후의 기간에 대한 실험도 수행하였다. 자료는 수발아 피해 관련 기간의 교정을 위한 training-set과 vali-set, 검증을 위한 test-set으로 구분하였다. training-set과 vali-set으로 교정한 결과, 출수 후 22일 후부터 24일동안에서 가장 높은 score를 나타내었다. test-set으로 검증한 결과는 3.0%보다 낮은 구간에서 수발아율을 약간 높게 예측한 경향이 있었지만, 높은 예측력을 보였다(R2=0.76). 따라서, 기계학습을 이용하여 특정기간동안의 기상요소들로 수발아율을 간단하게 예측할 수 있을 것으로 예상된다. 본 연구의 결과를 종합해 볼 때, 기계학습을 이용하여 특정 기간 동안에 평균 기온과 상대 습도, 그리고 총 강수량으로 높은 수발아율 예측 성능을 보였으며, 이 시스템을 이용하여 일반 농가들을 대상으로 수발아에 관한 피해를 예방할 수 있는 조기 수발아 예측 시스템으로 이용가능 할 것으로 판단된다. 하지만 품종마다 휴면 정도 차이로 인한 수발아 관련 기간에 차이가 있으므로, 다른 쌀가루용 벼 품종에 대해서도 추가로 조사하고, 개별 품종으로 세분화하여 분석한다면 좀 더 정확도 높은 예측 시스템을 개발할 수 있을 것으로 판단된다.

• 한국어교육
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• 제28권3호
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• pp.1-24
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• 2017

This article explores the developmental history of TOPIK over the last 20 years and its recent trends. Over the last two decades, TOPIK underwent two major systematic reforms, achieving both quantitative and qualitative growth over the course of its 52 testing sessions. TOPIK has utilized a six-level evaluation system from its inception to the present. The evaluation system was amended from the earlier six-test set - whereby each level corresponded with a separate test (1997~2005: the $1^{st}{\sim}9^{th}$) - to the three-test set (2006~2014: the $10^{th}{\sim}34^{th}$), and finally to the two-test set (2014~present: the $35^{th}{\sim}42^{nd}$). In the earlier exams, abilities in Vocabulary Grammar, Writing, Listening, and Reading were assessed. However, beginning with the $35^{th}$ TOPIK, abilities in Listening, Reading, and Writing (only in TOPIK II) were assessed and the evaluation of the writing section was changed to a task-based process, improving TOPIK into a more qualified analysis of proficiency. Over the last 20 years, the number of countries TOPIK is administered in has greatly increased from 4 to 73 countries, and the annual number of test-takers has also significantly increased from 2,692 to 250,141. The distribution of proficiency levels of the test-takers has shifted over time - initially "Beginner>Intermediate>Advanced" in the earlier exams, to "Intermediate>Advanced>Beginner" after the mid 2000s - as the number of those studying the Korean language for specific purposes and continuing education increased. Test-takers have indicated a shift in their purpose for taking the exam, initially citing "to assess proficiency" and more recently selecting "to study abroad," and this could also correlate with changes in the proportion of test-takers' proficiency level. In general, 85~95% of beginner, 50~65% of intermediate, and 45~60% of advanced test applicants passed the respective proficiency level. To date, no practices have yet been implemented to standardize the difficulty level longitudinally across test sets.

• Communications for Statistical Applications and Methods
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• 제5권2호
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• pp.411-416
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• 1998

A simple nonparametric test of complete or total independence is suggested for continuous multivariate distributions. This procedure first discretizes the original variables based on their order statistics, and then tests the hypothesis of complete independence for the resulting contingency table. Under the hypothesis of independence, the chi-squared test statistic has an asymptotic chi-squared distribution. We present a simulation study to illustrate the accuracy in finite samples of the limiting distribution of the test statistic. We compare our method to another nonparametric test of complete independence via a simulation study. Finally, we apply our method to the residuals from a real data set.

• Journal of the Korean Data and Information Science Society
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• 제15권1호
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• pp.129-139
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• 2004

We consider the problem of testing for outliers in generalized linear model. We proceed by first specifying a mean shift outlier model, assuming the suspect set of ourliers is known. Given this model, we discuss standard approaches to obtaining score test for outliers as an alternative to the likelihood ratio test.

• Journal of Computing Science and Engineering
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• 제3권3호
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• pp.165-180
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• 2009

The HKIB, or Hankookilbo, test collections are two archives of Korean newswire stories manually categorized with semi-hierarchical or hierarchical category taxonomies. The base newswire stories were made available by the Hankook Ilbo (The Korea Daily) for research purposes. At first, Chungnam National University and KISTI collaborated to manually tag 40,075 news stories with categories by semi-hierarchical and balanced three-level classification scheme, where each news story has only one level-3 category (single-labeling). We refer to this original data set as HKIB-40075 test collection. And then Yonsei University and KISTI collaborated to select 20,000 newswire stories from the HKIB-40075 test collection, to rearrange the classification scheme to be fully hierarchical but unbalanced, and to assign one or more categories to each news story (multi-labeling). We refer to this modified data set as HKIB-20000 test collection. We benchmark a k-NN categorization algorithm both on HKIB-20000 and on HKIB-40075, illustrating properties of the collections, providing baseline results for future studies, and suggesting new directions for further research on Korean text categorization problem.

• Journal of Information Processing Systems
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• 제13권5호
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• pp.1089-1102
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• 2017

In software systems, it has been observed that a fault is often caused by an interaction between a small number of input parameters. Even for moderately sized software systems, exhaustive testing is practically impossible to achieve. This is either due to time or cost constraints. Combinatorial (t-way) testing provides a technique to select a subset of exhaustive test cases covering all of the t-way interactions, without much of a loss to the fault detection capability. In this paper, an approach is proposed to generate 2-way (pairwise) test sets using genetic algorithms. The performance of the algorithm is improved by creating an initial solution using the overlap coefficient (a similarity matrix). Two mutation strategies have also been modified to improve their efficiency. Furthermore, the mutation operator is improved by using a combination of three mutation strategies. A comparative survey of the techniques to generate t-way test sets using genetic algorithms was also conducted. It has been shown experimentally that the proposed approach generates faster results by achieving higher percentage coverage in a fewer number of generations. Additionally, the size of the mixed covering arrays was reduced in one of the six benchmark problems examined.

• 한국어교육
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• 제28권1호
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• pp.221-250
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• 2017

This study aims to discuss the basic foundations to set levels and language skills for developing a Korean Proficiency Test for young and adolescent learners. Recently, there has been an increase in demand regarding young and adolescent learners from multicultural and overseas backgrounds. However, the current Korean Proficiency Test lacks the appropriate means to determine the Korean proficiency of young and adolescent learners with general purposes of language learning. Therefore, there is an urgent need for developing a specialized and new form of language assessment for young and adolescent learners who are exposed to a foreign language or a second language learning environment. The study examines and analyzes cases of foreign language examinations for young & adolescent learners; furthermore, the objectives and target were set based on the results of a needs analysis and in-depth interviews conducted among teachers and education officials in overseas Korean Hangeul Schools, international schools, elementary and secondary schools. Finally, the levels and language skills appropriate for the objectives of a proficiency test and target learners have been suggested.