• Journal of Korean Society of Environmental Engineers
• /
• v.39 no.12
• /
• pp.698-705
• /
• 2017

Environmental impact of a mobile phone charger containing recycled plastic was quantified using LCA and the environmental benefits from the use of recycled and virgin plastic were compared. The assessment considers potential environmental impacts across the whole life cycle of the charger including; pre-manufacturing; manufacturing; distribution; product use; and end-of-life stages and quantified six environmental impact categories; Abiotic depletion; Acidification; Eutrophication; Global warming; Ozone layer depletion; and Photochemical oxidants creation. The study showed that the environmental impacts of the use stage accounted for 94.4% and 70% in the resource depletion and global warming impact categories, respectively, and the environmental impacts of the pre - manufacturing stage accounted for more than 98% in the other impact categories. The main cause of the environmental impacts in the use stage was electricity consumed by the charger. The main cause in the pre-manufacturing stage was PBA (Printed Board Assembly) and external case manufacturing. In order to quantify the environmental benefits of recycled PC (Polycarbonate) in the exterior case, the environmental impacts of 1 kg production of recycled PC and virgin PC were evaluated. The environmental impact on the abiotic depletion of the recycled PC is estimated to be 30% compared to the virgin PC, and the impacts on the other impact categories of the recycled PC were less than 5% of the virgin plastic. Sensitivity analysis was performed for 12 items including site data and assumptions made. The sensitivity of each item was less than 10%. The results of this study confirm that designing compact and light PBA, improving charging efficiency, and use of recycled plastic are important design factors to reduce the environmental impact of a charger.

• Journal of The Korean Association For Science Education
• /
• v.36 no.5
• /
• pp.717-727
• /
• 2016

Using TIMSS survey data, we analyzed whether there were any significant changes in the learning environment of middle school science classes over the last 10 years. Our study selected questions from teachers and school principals' questionnaires and divided them by category: science class, teacher professional development, and school environment. The science class components were subdivided into three categories: science learning activities, evaluation, and homework. Within teacher professional development, the sub-categories included teacher training, collaboration to improve teaching, and teacher evaluation. School environment subdivided into two aspects, these being school characteristics and school system. Our research confirmed that there has been a positive change overall in learning environments. However, most classes are teacher-conducted and also teacher-oriented; the proportion of science investigation activities has declined compared against the prior ten years. Our study show that students do not engage in a range of inquiry-related activities. The questions on tests and examinations involve mostly knowledge application and understanding, although recent methods of evaluation show improvement. As for the science teachers, they participate in many professional development programs but focus on science content, science curriculum, and pedagogy. In addition, teachers do not have many opportunities to participate in the training to integrate information technology into science, science assessment, or improving students' critical thinking or inquiry skills. The teachers are satisfied with their profession, and the shortage of science resources does not seem to affect instruction.

• Journal of Korea Game Society
• /
• v.18 no.1
• /
• pp.7-18
• /
• 2018

As coding education is ubiquitous in elementary or higher school curriculum, puzzle-based coding platforms such as Scratch or Entry have been popularly deployed and employed by many Korean coding educational institutions. In this article, we propose a quantitative students' coding assessment methodology and discuss several issues of the method. Besides, we show its usefulness through case studies shown in our proprietary coding platform called "CodingPuzzle" system. Additionally, we describe detailed design and implementation issues of our coding assessment system that has already been ported to the CodingPuzzle system and is currently under operation.

• The KIPS Transactions:PartD
• /
• v.19D no.2
• /
• pp.133-138
• /
• 2012

Queries entered in a search box are the results of users' activities to actively seek information. Therefore, search logs are important data which represent users' information needs. The purpose of this study is to examine if there is a relationship between the results of queries automatically classified and the categories of documents accessed. Search sessions were identified in 2009 NDSL(National Discovery for Science Leaders) log dataset of KISTI (Korea Institute of Science and Technology Information). Queries and items used were extracted by session. The queries were processed using an automatic classifier. The identified queries were then compared with the subject categories of items used. As a result, it was found that the average similarity was 58.8% for the automatic classification of the top 100 queries. Interestingly, this result is a numerical value lower than 76.8%, the result of search evaluated by experts. The reason for this difference explains that the terms used as queries are newly emerging as those of concern in other fields of research.

• The Korean Journal of Applied Statistics
• /
• v.24 no.3
• /
• pp.535-546
• /
• 2011

This study develops statistical models for the binary forecast of Asian dust days over South Korea in the winter season. For this study, we used three kinds of data; the rst one is the observed Asian dust days for a period of 31 years (1980 to 2010) as target values, the second one is four meteorological factors(near surface temperature, precipitation, snowfall, ground wind speed) in the source regions of Asian dust based on the NCEP reanalysis data and the third one is the large-scale climate indices. Four kinds of statistical models(multiple regression models, logistic regression models, decision trees, and support vector machines) are applied and compared based on skill scores(hit rate, probability of detection and false alarm rate).

• Journal of the Institute of Electronics and Information Engineers
• /
• v.50 no.6
• /
• pp.221-227
• /
• 2013

This paper proposes an improved steganalysis method based on image categorization. In general, most steganalysis methods extract the statistical moments based features which contain the global natures of images regardless of their inherent characteristics. However, the steganalysis method based on the statistical moments leads to degraded performance by applying to images with different complexity. In this paper, we decompose an 8-bit image into an upper 4-bit plane and a lower 4-bit plane, and categorize the image with two classes according to the correlation coefficient between decomposed sub-images. Two independent steganalyses can be performed for the categorized images. Since our method uses independent steganalysis technique according to the image category, it can reduce the drawback of the steganalysis methods utilizing the statistical moments. The performance of the proposed scheme is compared with well-known four steganalysis methods. Experiment results show that the proposed scheme has higher detection rate than previous methods.

• Journal of the Korean Society for information Management
• /
• v.39 no.1
• /
• pp.69-90
• /
• 2022

As basic data that can systematically support and evaluate R&D activities as well as set current and future research directions by grasping specific trends in domestic academic research, I sought efficient ways to assign standardized subject categories (control keywords) to individual journal papers. To this end, I conducted various experiments on major factors affecting the performance of automatic classification, focusing on feature selection techniques, for the purpose of automatically allocating the classification categories on the National Research Foundation of Korea's Academic Research Classification Scheme to domestic journal papers. As a result, the automatic classification of domestic journal papers, which are imbalanced datasets of the real environment, showed that a fairly good level of performance can be expected using more simple classifiers, feature selection techniques, and relatively small training sets.

• Korean Journal of Construction Engineering and Management
• /
• v.16 no.3
• /
• pp.24-35
• /
• 2015

Aging educational facility shall be managed and maintained through integrated service perspectives, in consideration of functions of each facility to provide safe and comfortable environment, rather than temporarily fixing/repairing problems. For doing this, it is a must to firstly understand the limitation of highly biased performance-based maintenance practice, which is a most common type applied at present, and therefore to establish maintenance system that reflects the functions and characteristics of maintenance service that a facility was designed with. Therefore, the objective of this study is to find items that have an influence on service level recognition in order to fairly evaluate service functions of educational facilities, and subsequently to use these factors as ingredients of establishing a consistent and efficient maintenance system. Therefore this study proposed explanatory variables to measure influential factors for each major maintenance category. Then appropriate statistical verification was carried out on questionnaires that collected from a number of industry experts to test its fe asibility.

• The Journal of the Korea Contents Association
• /
• v.22 no.5
• /
• pp.1-15
• /
• 2022

In this study, text analysis was performed on the mealkit product review data to identify factors affecting the evaluation of the mealkit product. The data used for the analysis were collected by scraping 334,498 reviews of mealkit products in Naver shopping site. After preprocessing the text data, wordclouds and sentiment analyses based on word frequency and normalized TF-IDF were performed. Logistic regression model was applied to predict the polarity of reviews on mealkit products. From the logistic regression models derived for each product category, the main factors that caused positive and negative emotions were identified. As a result, it was verified that text analysis can be a useful tool that provides a basis for maximizing positive factors for a specific category, menu, and material and removing negative risk factors when developing a mealkit product.

• Journal of the Society of Naval Architects of Korea
• /
• v.61 no.2
• /
• pp.125-134
• /
• 2024

The Safe Operating Envelope (SOE) combined with Short-Take-Off and Vertical Landing (STOVL) performance is an essential consideration of a light aircraft carrier for design of hull shape with excellent seakeeping performance in terms of naval air operations as well as traditional naval ship missions such as Transit and Patrol (TAP), and Replenishment at Sea (RAS) and so on. A variety of procedures are systematically combined to determine SOE considering rather complicated missions associated with operation of aircraft onboard. The evaluation of take-off and landing safety missions onboard should consider wind effect on deck and severer seakeeping indices and standards compared with conventional naval ships. In order to support take-off and landing missions, various support activities of the crews are required. So, additional evaluation is needed for indicators such as MSI(Motion sickness Index) and MII(Motion Induced Interruptions), which are quantitative indicators of work ability that appear as a result of motion response. In this study, a standard procedure is developed including the seaworthiness performance indicators, standards, and evaluation procedures that should be considered during design of STOVL aircraft carrier. Analysis results are discussed in terns of air-wake on deck as well as seakeeping indices associated with design parameter changes in view of conceptual design of a light aircraft carrier.