This study endeavors to enrich investment prospects in cryptocurrency by establishing a rationale for investment decisions. The primary objective involves evaluating the predictability of four prominent cryptocurrencies – Bitcoin, Ethereum, Litecoin, and EOS – and scrutinizing the efficacy of trading strategies developed based on the prediction model. To identify the most effective prediction model for each cryptocurrency annually, we employed three methodologies – AutoRegressive Integrated Moving Average (ARIMA), Long Short-Term Memory (LSTM), and Prophet – representing traditional statistics and artificial intelligence. These methods were applied across diverse periods and time intervals. The result suggested that Prophet trained on the previous 28 days' price history at 15-minute intervals generally yielded the highest performance. The results were validated through a random selection of 100 days (20 target dates per year) spanning from January 1st, 2018, to December 31st, 2022. The trading strategies were formulated based on the optimal-performing prediction model, grounded in the simple principle of assigning greater weight to more predictable assets. When the forecasting model indicates an upward trend, it is recommended to acquire the cryptocurrency with the investment amount determined by its performance. Experimental results consistently demonstrated that the proposed trading strategy yields higher returns compared to an equal portfolio employing a buy-and-hold strategy. The cryptocurrency trading model introduced in this paper carries two significant implications. Firstly, it facilitates the evolution of cryptocurrencies from speculative assets to investment instruments. Secondly, it plays a crucial role in advancing deep learning- based investment strategies by providing sound evidence for portfolio allocation. This addresses the black box issue, a notable weakness in deep learning, offering increased transparency to the model.

본 연구는 제5차 국가산림자원조사(2006-2010)에서 조사된 편백을 대상으로 흉고직경에 따른 수고 생장곡선식과 초기 수고생장 모델을 개발하여 편백의 초기 생장특성을 고려한 합리적인 산림경영계획 수립에 필요한 기초자료를 제공할 목적으로 실시하였다. 연구자료는 제5차 국가산림자원조사 자료 중 편백 표준목 353본에 대한 수고, 흉고직경, 연륜생장 자료를 이용하였다. 흉고직경에 따른 수고 생장곡선식은 Petterson 식, Log 식, Michailow 식을 이용하여 개발하였으며, 연령에 따른 초기 수고생장 모델은 Chapman-Richards 식, Gompertz 식, Schumacher 식을 이용하여 개발하였다. 본 연구 결과, 모델 검정을 통하여 흉고직경에 따른 수고 생장곡선식은 Petterson 식이 가장 적합한 것으로 나타났으며, 초기 수고생장 모델은 Gompertz 식이 가장 적합한 것으로 나타났다. 본 연구에서 개발한 초기 수고생장 모델을 그래프로 나타낸 결과 편백은 13년생일 때 연간 수고생장량이 0.54m로 가장 많은 것으로 나타났다. 본 연구 결과는 편백의 생장 특성 관련 연구에 활용할 수 있을 뿐 아니라 초기의 편백 조림지에 대하여 합리적인 산림경영계획 수립에 유용한 기초자료가 될 것으로 기대된다.

Solenopsis geminata has been found in South Korea, suggesting a risk of its invasion has been increased by rapid climate change. This situation requires species distribution modeling to predict possibility of Solenopsis geminata introduction, but information necessary for performing it is very limited. In this study, we developed a map for global distribution of Solenopsis geminata so that the map can be used for future species distribution modeling. Also, as the first step to assess Solenopsis geminata introduction, climatic similarity between its origin (Puerto Rico) and major cities in South Korea was compared. We used ArcMap (version 10.0) for creating the distribution map by obtaining current habitat from public database, and CLIMEX was used to compare climates based on CMI value. The result showed that climates were not similar as indicated by CMI less than 0.52, suggesting the risk of intial introduction is low under the current climatic condition. However, it should be noted that climatic similarity did not consider biological characteristics of Solenopsis geminata and climate change. Thus, the next study will be devoted to climatic suitability simultaneously considers meteorological data, distribution and biological information.

The flow of the 4th Industrial Revolution calls for the innovation of the traditional business models of the manufacturers. Servitization is a corporate strategy to respond to changes in the business environment. These days, the value that the market demands can be created on the basis of the product-service integration. Thus the manufacturers must pursue the fundamental innovation of the current strategy and business models. It is necessary to create common values with customers through providing product-service integrated offerings beyond the development, production, and delivery. The purpose of this study is to develop the evaluation indicators for selecting suppliers when the manufacturer who offers the value of product-service integration needs to obtain the resources from outside. The case company in this study is the manufacture firm conducting the retail IoT business as a new business. The Delphi method is used to develop the evaluation indicators for selecting suppliers. This study suggests the academic implications providing the perspective of Servitizaiton by using Delphi method, and the practical implications applying the creating value method of Servitization by collecting the opinions from both value providers and value consumers in the process of developing the evaluation indicators.

To investigate the value co-creation process in wellness tourism, this study constructed a structural equation model of customer interactions with (1) the environment, (2) service employees, and (3) other customers relating to customer-perceived value and customer engagement. Empirical data were collected from 528 survey respondents who were at wellness tourism resorts. The results reveal that all three types of interaction have positive effects on customer-perceived value, and that perceived value positively affects customer engagement. Based on this finding, management recommendations for wellness tourism service enterprises are given.

As a system complexity increases and technology innovation progresses rapidly, leasing the equipment is considered as an important issue in many engineering areas. In practice, many engineering fields lease the equipment because it is an economical way to lease the equipment rather than to own the equipment. In addition, as the maintenance actions for the equipment are costly and need a specialist, the lessor is responsible for the maintenance actions in most leased contract. Hence, the lessor should establish the optimal maintenance strategy to minimize the maintenance cost. This paper proposes two periodic preventive maintenance policies for the leased equipment. The preventive maintenance action of policy 1 is performed with a periodic interval, in which their intervals are the same until the end of lease period. The other policy is to determine the periodic preventive maintenance interval minimizing total maintenance cost during the lease period. In addition, this paper presents two decision-making models to determine the preventive maintenance strategy for leased equipment based on the lessor’s preference between the maintenance cost and the reliability at the end of lease period. The structural properties of the proposed decision-making model are investigated and algorithms to search the optimal maintenance policy that are satisfied by the lessor are provided. A numerical example is provided to illustrate the proposed model. The results show that a maintenance policy minimizing the maintenance cost is selected as a reasonable decision as the lease term becomes shorter. Moreover, the frequent preventive maintenance actions are performed when the minimal repair cost is higher than the preventive maintenance cost, resulting in higher maintenance cost.

As the global uncertainty of manufacturing has increased and the quality problem has become global, the recall has become a fatal risk that determines the durability of the company. In addition, as the convergence of PSS (product-service system) product becomes common due to the development of IT convergence technology, if the function of any part of hardware or software does not operate normally, there will be a problem in the entire function of PSS product. In order to manage the quality of such PSS products in a stable manner, a new approaches is needed to analyze and manage the hardware and software parts at the same time. However, the Fishbone diagram, FTA, and FMEA, which are widely used to interpret the current quality problem, are not suitable for analyzing the quality problem by considering the hardware and software at the same time. In this paper, a quality risk assessment model combining FTA and FMEA based on defect rate to be assessed daily on site to manage quality and fishbone diagram used in group activity to solve defective problem. The proposed FTA-FMEA based risk assessment model considers the system structure characteristics of the defect factors in terms of the relationship between hardware and software, and further recognizes and manages them as risk. In order to evaluate the proposed model, we applied the functions of ITS (intelligent transportation system). It is expected that the proposed model will be more effective in assessing quality risks of PSS products because it evaluates the structural characteristics of products and causes of defects considering hardware and software together.

For the asset management of a water pipe network, it would be necessary to understand the extent of the maintenance cost required for the water pipe network for the future. This study would develop a method to draw the optimum cost required for the maintenance of the water pipe network in waterworks facilities to maintain the aim revenue water ratio and to achieve the target revenue water ratio, considering the water service providers’ waterworks condition and revenue water ratio comprehensively. This study conducted a survey with 96 water service providers as of the early 2015 and developed models to estimate the optimum maintenance cost of the water pipe network, considering the characteristics of the water service providers. Since the correlation coefficient of all the developed models was higher than 0.95, it turned out that it had significant reliability, which was statistically significant. As a result of applying the developed models to the actual water service providers, it was drawn that increasing revenue water ratio to more than a certain level can reduce the maintenance cost of the water pipe network by a great deal. In other words, it is judged that it would be the most efficient to secure the reliability of waterworks management by increasing the short-term revenue water ratio to more than a certain level and gradually increase the revenue water ratio from the long-term perspective. It is expected that the proposed methodology proposed in this study and the results of the study will be used as a basic research for planning the maintenance of water pipe network or establishing a plan for waterworks facilities asset management.

The purpose of the study was to investigate the causal relationships among factors affecting L2 reading achievement using a structural equation modeling (SEM) analysis. A total of 327 Korean EFL high school students completed a questionnaire on L2 reading motivation and strategies. The students’ L2 listening and reading comprehension abilities were measured by scores on the practice test for Scholastic Aptitude Test (PSAT) and self-assessed listening and reading proficiency. The study results showed that the students’ L2 reading efficacy, L2 reading strategy use, and L2 listening skills were significant predictors of their L2 reading achievement, while L2 reading motivation showed no significant relation with reading achievement. The nonsignificant path loading between reading motivation and reading achievement implies that reading motivation alone is not sufficient to promote students’ L2 reading proficiency. The final SEM model indicated a relatively strongest contribution of L2 listening ability over L2 reading efficacy and strategy use to L2 reading achievement. Pedagogical implications based on the findings are discussed.

In this research, technology innovation capability evaluation model for small and medium enterprises was developed. To develop technology innovation capability evaluation model, two analytic technic was used. First one is AHP (Analytic Hierarchy Process) to give weight to each main index. Second one is fuzzy set theory to represent ambiguous index to numerical value. Finally, technology innovation capability evaluation model was achieved in combination with the same weight to AHP analysis and fuzzy set theory. With these results, small and medium enterprises can know important point in terms of strengthening the innovation capability evaluation.

This study aims to develop an English writing model using pattern-based reading materials and to apply it to the elementary classroom. The meaning of “patterns” was searched for in the language learning and teaching methods, and their roles were examined in terms of language acquisition and learning. The writing class was connected to the reading class so that learners could properly model and transfer their forms and meanings of the patterns recognized in the reading class to what they want to write in the writing class. The experiment was conducted on one class of grade 6 elementary school students in which the reading and writing class was integrated into the regular English class during one semester. Six pattern-based reading materials were selected with a range of genres including stories and poems. The effect of the pattern-based reading materials on the writing class was examined through writing test and a questionnaire about the affective domain before and after the experiment. The result showed that writing scores were increased significantly in all the leveled-group learners. As for the affective domain, interest, participation, confidence, and adventure each had a significantly increased score. The sense of adventure increased the most. This is considered attributable to the feedback which ignored grammatically trivial errors and focused on how to properly express the contents learners wanted to write.

In this paper, a System Dynamics(SD) computer simulation model has been developed to assess the effects of developing and providing an alternate water source. A water service index was also developed to estimate the level of overall customer satisfaction on water supply service. Data from the Busan water supply service and the Korea Development Institute regarding the Nak Dong river bank storage development were utilized during the modeling processes. Some important indicators of the system under study were analyzed by the simulations of development of the alternate water source for Busan. The developed SD model and the water service index can be further utilized as a tool that can assess the extent and timing of an additional service improvement project.

기후변화에 따른 한반도 난대지역 상록수종인 후박나무의 적지예측모델을 개발하기 위하여 본 연구가 수행되었다. 생장 및 입지환경 인자들간의 관계 구명을 통하여 양적·질적 자료 분석이 가능한 수량화 분석 방법에 의하여 후박나무의 적지예측 평가기준을 도출하였으며, 적지예측 프로그램은 ESRI, ArcView GIS 프로그램을 이용하여 개발하였다. 개발된 프로그램은 적지예측의 정확성 검토를 위하여 다양한 난대 상록활엽수가 분포하고 있는 전남 완도 지역에 적용하였다. 후박나무의 적지예측 분석 결과, 최적 생육 입지환경은 계곡부위의 경사도가 15~20°로, 토양습도가 적윤하며 토심이 50~70cm인 붕적토로 나타났다. 또한 암석노출이 30% 이상으로 바람의 영향을 거의 받지 않는 곳으로 나타났다. 적지예측 등급별 면적과 면적비는Ⅰ등급 1,347.4ha, 23.0%, Ⅱ등급 2,295.2ha, 39.2%, Ⅲ등급 1,350.9ha, 23.1%, Ⅳ등급 856.3ha, 14.6%로 분석되었으며, 등급별 면적비는 Ⅱ등급지가 39.2%로 가장 높게 나타났다.

In this paper, due to the instability of the domestic market, global competition is intensifying in the current situation of global capacity building of SMEs for the purpose of developing a diagnostic indicator placed on the purpose. In this model, the results of applying several companies overall global innovation pilot enterprises and non-rated global innovative companies awarded significant difference between the score and the ability to believe the show. Non-global innovation companies, the relative firm size factor and R&D investment and patent number of factors are lacking appeared shone This is a common small business nature of the majority of companies small and R&D investment, the absolute amount is insufficient to reflect that, but the global innovator in the case of firm size and the relatively large amount of investment that never shows.

For maintaining adequate psychometric properties when reducing the number of items from an instrument, item level psychometrics is crucial. Strategies such as low item correlation or factor loadings, using classical test theory, have traditionally been advocated. The purpose of this study is to describe the development of a new short form assessing the impact of low back pain on physical activity. Rasch measurement model has been applied to the International Classification of Functioning, Disability and Health Activity Measure (ICF-AM). One hundred and one individuals with low back pain aged 19-89 years (mean age: 48.1±17.3) who live in the community were participated in the study. Twenty-seven items of lifting/carrying construct of the ICF-AM were analyzed. Ten items were selected from the construct to create a short form. Item elimination criteria include: 1) high or low mean square (out of the range: .6-1.4 for the fit statistics), 2) similar item calibrations to adjacent items, 3) person separation value, and item-person map for potential gap in person ability continuum. All 10 items of the short form fit to the Rasch model except one item (i.e., carrying toddler on back). Despite its high infit and outfit statistics (1.90/2.17), the item had to be reinstated due to potential gaps at the upper extreme of person ability level. The short form had a slightly better spread of person ability continuum compared to the entire set of item. The created short form separated individuals with low back pain into nearly 4 groups, while the entire set of items separated the individuals into 6 groups. The findings prompted multidimensional models for better explanation of the lifting/carrying domain. The item level psychometrics based on the Rasch model can be useful in developing short forms with rationally retained items.