• Journal of Information Processing Systems
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• 제15권3호
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• pp.694-706
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• 2019

In this study, we applied the long short-term memory (LSTM) model to classify the cryptocurrency price time series. We collected historic cryptocurrency price time series data and preprocessed them in order to make them clean for use as train and target data. After such preprocessing, the price time series data were systematically encoded into the three-dimensional price tensor representing the past price changes of cryptocurrencies. We also presented our LSTM model structure as well as how to use such price tensor as input data of the LSTM model. In particular, a grid search-based k-fold cross-validation technique was applied to find the most suitable LSTM model parameters. Lastly, through the comparison of the f1-score values, our study showed that the LSTM model outperforms the gradient boosting model, a general machine learning model known to have relatively good prediction performance, for the time series classification of the cryptocurrency price trend. With the LSTM model, we got a performance improvement of about 7% compared to using the GB model.

• 복식
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• 제58권9호
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• pp.18-28
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• 2008

The purpose of this study is to examine the Characteristics of Fashion Trends($1996{\sim}2005$) of Korea by the trend elements - style, fabric and color. The results of this study are as followed. During 10years, 'modern(18%)', 'elegant(11%)' and 'romantic(10%)' styles were shown in order, and colors of YR(17%), Y(14%), R(13%) and PB(11%) were shown in order. Considering tones, m(16%), d(12%), gy(11%) and s(10%) tones were in the order of frequency. In the fabric trend 'elegant(19%)', 'modern(14%)' and 'natural(14%)' images showed the high frequency. Since 2000's, style trends and fabric trends were subdivided, and the contrary images coexisted. The trend images of 'natural', 'retro', 'manish' and 'fun' were mainly used in fabric trend, and 'romantic' and 'classic' images were frequently used in style trend. The changes of trend images in style and fabric have been similar until the early 2000's but the cycle of trend of style became shorter than fabric trend. Therefore the cycle of fabric trend should be changed to be a short term and subdivided in company with style trend.

• 정보학연구
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• 제12권4호
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• pp.19-24
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• 2009

Recently, for the efforts of low-carbon deduction and to solve the problems of global warming, many industrial nations in world have been strengthening positively their competitive power into the research, development and industrialization of new renewable sources of energy and clean energy. In the most promising source of photovoltaic, it is essential that the government take an initiative role to develop and industrialize the materials, ingot or wafer, solar cell, power conditioning system and photovoltaic system, and need to establish both short-term and long-term technical development of goal setting and forward plan in the direction of the technical development strategy and forward industrialization for the strengthening of world market. This paper analyze new technology, policies and the market trend of photovoltaic field which are currently strategically and actively enhancing the research, development and practical-industralization by Korea and other nations.

• 한국대기환경학회지
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• 제19권2호
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• pp.179-189
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• 2003

The concentration of gaseous elemental mercury (Hg) was measured concurrently with relevant environmental parameters from Yang-Jae monitoring station in Seoul during Sept. 1997 to June 2002. Although data collection was disrupted for certain periods, the grand mean concentration of Hg for this five year period was found at 5.32 $\pm$ 3.53 ng m$^{-3}$ (N = 27,170). Because of short resolution of data acquisition, we were able to examine the temporal variability of Hg at varying time scale. The diurnal variability of Hg, when investigated for each of those five years, indicated consistently the dominance of nighttime over daytime. If examined at seasonal scale, Hg level was systematically higher during winter/spring than summer/fall period. The results of this short-term variability were best explained by the combined effects of such factors as meteorological conditions (formation of inversion layer and seasonal changes) and anthropogenic source processes. However, examination of long-term variation Pattern was much more complicated to explain. Thus, extension of our study is needed to diagnose the future direction in long-term trend of Hg behavior.

• 복식문화연구
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• 제27권1호
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• pp.1-10
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• 2019

Firefighters wear Personal Protective Equipment (PPE) for protection from environmental hazards. However, due to the layers of protective functions, the PPE inevitably adds excessive weight, bulkiness, and thermal stress to firefighters. This study investigated the adverse impact of wearing PPE as an occupational stressor on the firefighter's cognitive functioning. Twenty-three firefighters who had been involved in firefighting at least for 1 year were recruited. The overall changing trend in the firefighter's cognitive functioning (short-term memory, long-term memory, and inductive reasoning) was measured by the scores of three standardized cognitive tests at the baseline and the follow-up, after participating in a moderate-intensity physical activity, wearing a full ensemble of the PPE. The study findings evinced the negative impact of the PPE on the firefighter's cognitive functioning, especially in short-term memory and inductive reasoning. No significant influence was found on the firefighter's long-term memory. The results were consistent when the participant's age and BMI were controlled. The outcomes of the present study will not only fill the gap in the literature, but also provide critical justification to stakeholders, including governments, policymakers, academic communities, and industry, for such efforts to improve human factors of the firefighter's PPE by realizing the negative consequences of the added layers and protective functions on their occupational safety. Study limitations and future directions were also discussed.

• 한국대기환경학회지
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• 제29권5호
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• pp.545-552
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• 2013

While attainment rates for $SO_2$ and CO approached 100%, those for $PM_{10}$, $NO_2$, and $O_3$ have been low during the past decade. The attainment rates for 24-h $PM_{10}$ and 8-h $O_3$ have been only 1~3% and 5~12%, respectively, since the standards were strengthened in 2007. Variations in the 99th percentiles of 24-h $PM_{10}$, 8-h $O_3$, and 24-h $NO_2$, which are used as criteria for determining exceedance of standards, were examined by region. Because the analysis was based on short-term high-concentrations, the effects of Asian dust were observed for $PM_{10}$. Accordingly, it is necessary to specify whether exceptional events such as Asian dust will be included or not in determining the exceedances of standards. While variations in $NO_2$ were not large, there was an increasing trend in $O_3$. In the Yeongnam region, the increasing rate of $O_3$ concentrations was small although the decreasing rate of $NO_2$ was the greatest. In the Gangwon region, $NO_2$ concentrations were almost unchanged, but $O_3$ concentrations experienced a significant increase. Regional management strategies targeting short-term high concentrations of criteria pollutants analogous to the Special Act for the greater Seoul area will aid in improving attainment rates.

• 한국도로학회논문집
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• 제17권4호
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• pp.135-141
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• 2015

PURPOSES: This study has been conducted to determine a homogeneous segment and integration to improve the efficiency of short-term traffic count. We have also attempted to reduce the traffic monitoring budget. METHODS: Based on the statistical approach, a homogeneous segment in the same road section is determined. Statistical analysis using t-test, mean difference, and correlation coefficient are carried out for 10-year-long (2004-2013) short-term count traffic data and the MAPE of fresh data (2014) are evaluated. The correlation coefficient represents a trend in traffic count, while the mean difference and t-score represent an average traffic count. RESULTS : The statistical analysis suggests that the number of target segments varies with the criteria. The correlation coefficient of more than 30% of the adjacent segment is higher than 0.8. A mean difference of 36.2% and t-score of 19.5% for adjacent segments are below 20% and 2.8, respectively. According to the effectiveness analysis, the integration criteria of the mean difference have a higher effect as compared to the t-score criteria. Thus, the mean difference represents a traffic volume similarity. CONCLUSIONS : The integration of 47 road segments from 882 adjacent road segments indicate 8.87% of MAPE, which is within an acceptable range. It can reduce the traffic monitoring budget and increase the count to improve an accuracy of traffic volume estimation.

• 한국콘텐츠학회논문지
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• 제11권6호
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• pp.1-7
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• 2011

KOSPI는 정치 및 경제를 포함한 다양한 요소에 영향을 받는 관계로 정확한 단기 KOSPI 예측 방법론 개발은 매우 어려운 문제로 여겨지고 있다. 본 논문에서는 가중 퍼지소속함수 기반 신경망(NEWFM; neural network with weighted fuzzy membership functions)의 특징 추출기법을 사용하여 5일 동안의 주가 단기추세를 예측하는 방안을 제안한다. 비중복면적 분산 측정법에 의해 중요도가 가장 낮은 특징입력을 하나씩 제거하면서 최소의 특징입력을 선택한다. 특징입력으로써 기술지표를 이용하여 얻은 데이터를 웨이블릿 변환을 이용하여 39개의 계수들을 추출한다. 이들 39개의 특징입력 중 비중복면적 분산측정법에 의해서 추출된 12개의 계수가 사용된다. 제안된 방법에서는 민감도가 72.79%, 특이도가 74.76%, 정확도가 73.84%를 나타낸다.

• Journal of Information Processing Systems
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• 제15권4호
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• pp.920-930
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• 2019

To figure out the impact of debt financing on the profits of industrial enterprises, it starts with calculating the first differences against the logarithms of the cost profit ratios and the debt asset ratios of Chinese industrial enterprises during 179 months from 2002 to 2016; next, it runs the cointegration test and afterwards the regression test to analyze the obtained first differences, and still next uses the Simulink software to get the regularity of those changes. It finds out that there is not only a long-term stable relationship between the enterprises' profits and debts, but also a steady time series trend within a short term. The profit rate positively correlates to the debt asset ratio, and profit for the current term positively correlates to the profit for the previous term. It indicates that properly raised debts can help increase the profit rate of the industrial enterprises, and a higher previous profit level can help improve the current profit level.

• 국제학술발표논문집
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• The 2th International Conference on Construction Engineering and Project Management
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• pp.601-610
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• 2007

Responding to the fierce market competition and trying to cut personnel costs, the construction industry in Taiwan is adopting atypical employment in human resource. To discover this trend, this study employed a questionnaire survey to investigate the current use of atypical employment by domestic contractors and its possible impacts on the industry. According to the 103 returned valid questionnaires, 40.8% of the respondent contractors have applied some atypical employment types in recent three years and most of them used fixed-term employment. The major reasons the contractors used atypical employees are to reduce personnel costs, to deal with business fluctuations and to streamline personnel. According to the respondents, there is no significant difference between the advantages and disadvantages of using a large number of atypical employees in the short term. However, in the long term, atypical employment is generally more disadvantageous than advantageous.