• International Journal of Internet, Broadcasting and Communication
• /
• v.8 no.3
• /
• pp.12-24
• /
• 2016

Recently, as the price per bit is decreasing at a fast rate, flash memory is considered to be used as primary storage of large-scale database systems. Although flash memory shows off its high speeds of page reads, however, it has a problem of noticeable performance degradation in the presence of increasing update workloads. When updates are requested for pages with random page IDs, in particular, the shortcoming of flash tends to impair significantly the overall performance of a flash-based database system. Therefore, it is important to have a way to efficiently update the B+-tree, when it is stored in flash storage. This is because most of updates in the B+-tree arise at leaf nodes, whose page IDs are in random. In this light, we propose a new flash B+-tree that stores up-to-date versions of leaf nodes in sibling-leaf blocks (SLBs), while updating them. The use of SLBs improves the update performance of B-trees and provides the mechanism for fast key range searches. To verify the performance advantages of the proposed flash B+-tree, we developed a mathematical performance evaluation model that is suited for assessing B-tree operations. The performance comparisons from it show that the proposed flash B+-tree provides faster range searches and reduces more than 50% of update costs.

• Transactions on Electrical and Electronic Materials
• /
• v.18 no.6
• /
• pp.350-358
• /
• 2017

Recently, owing to increased interest in low-carbon energy supplies, renewable energy sources such as photovoltaics and wind turbines in distribution networks have received considerable attention for generating clean and unlimited energy. The presence of energy storage systems (ESSs) in the promising field of active distribution networks (ADNs) would have direct impact on power system problems such as encountered in probabilistic distributed generation (DG) model studies. Hence, the optimal procedure is offered herein, in which the simultaneous placement of an ESS, photovoltaic-based DG, and wind turbine-based DG in an ADN is taken into account. The main goal of this paper is to maximize the net present value of the loss reduction benefit by considering the price of electricity for each load state. The proposed framework consists of a scenario tree method for covering the existing uncertainties in the distribution network's load demand as well as DG. The collected results verify the considerable effect of concurrent installation of probabilistic DG models and an ESS in defining the optimum site of DG and the ESS and they demonstrate that the optimum operation of an ESS in the ADN is consequently related to the highest value of the loss reduction benefit in long-term planning as well. The results obtained are encouraging.

• Journal of Distribution Science
• /
• v.16 no.2
• /
• pp.47-51
• /
• 2018

Purpose - Typically, retailers will want PB(Private Brand) products to expand to the needs of low-PB loyal customers as well as existing PB(Private Brand) loyal customers. Therefore, a strategy of minimizing the share of the manufacturer brand in the distributor can be considered as a way to maximize the profit of the distributor. Research design, data, and methodology - In the previous study, the researches about the rivalry and conflict between the NB(National Brand) products and the PB products were mainly made. Previous studies did not model inter-national brand-level competition and inter-store competition. In addition, they have focused only on distributors' decisions from the manufacturer's perspective, and assume channel members have the same level of members(Choi, 1996). Results - This paper tries to apply the game theory to researches on how retailers can maximize the benefits of distributing NB(National Brand) products and PB(Private Brand) products, while distributors can also take advantage of their profits. Conclusions - It was found that providing cheap PBs did not help manufacturers and distributors. Distributors and manufacturers' profits were determined by consumers who purchased NB products that were higher in price and higher in perceived quality before providing existing PB products to consumers.

• The Journal of Asian Finance, Economics and Business
• /
• v.7 no.9
• /
• pp.201-208
• /
• 2020

Terms of trade is an important indicator of the welfare gains from international trade to the exporting country. Terms of trade of oil-exporting countries are hypothesized to depend primarily on oil prices. The study assesses the relation between oil prices and the terms of trade of Saudi Arabia. The study uses the Autoregressive Distributed Lag method to determine the cointegration between the country's terms of trade and oil prices for the period 2000-2018. The data for net barter terms of trade is taken from World Development Indicators and oil price is taken from Saudi Arabian Monetary Agency. The results show that oil prices and terms of trade are cointegrated and any disequilibrium between the two variables is corrected by 35% in a year. The study also reports a positive relationship between the two items, both in the short run and long run. Diagnostic tests indicate the model to be fit. The results suggest that, for a primarily oil-producing country like Saudi Arabia, the terms of trade depend on oil prices. The study fills the gap in the literature on the study of terms of trade for Saudi Arabia for the last few years, where there has been a high volatility in oil prices.

• KSII Transactions on Internet and Information Systems (TIIS)
• /
• v.10 no.12
• /
• pp.5616-5642
• /
• 2016

Different from traditional auctions, electronic auctions provide a platform to allow bidders and auctioneers merchandise to each other over network anytime and anywhere. Auctioneers can publish information of goods, and bidders can choose the interested targets through this bidding platform. To ensure the fairness and security of electronic auctions, Li et al. have proposed a practical electronic auction scheme which can confirm the requirement of strong anonymity, bidding privacy, and secret bidding price. However, we have found out that Li et al.'s scheme may lurk the risk of the denial-of-service attack during the bidding phase in a sealed-bid auction. Thus, we propose a brand-new sealed-bid auction mechanism, in which the essentials of e-auction can be firmly preserved. In particular, each bidder only needs to register at the center once and then can join to multiple plays launched by different auctioneers. Moreover, the correctness of mutual authentication is confirmed according to the BAN logic model.

• Journal of Information Technology Applications and Management
• /
• v.24 no.4
• /
• pp.93-115
• /
• 2017

The ability of smartphones to facilitate various services like mobile banking, e-commerce and mobile payments has made them part of consumers' lives. Conjoint analysis (CA) is a marketing research approach used to assess how consumers' preferences for products or services develop. The potential applications of CA are numerous in consumer electronics, banking and insurance services, job selection and workplace loyalty, consumer packaged goods, and travel and tourism. Choice-Based Conjoint (CBC) analysis is the most commonly used CA approach in marketing research. The purpose of this study is to utilise CBC analysis to investigate the relative importance of smartphone attributes that influence consumer smartphone preference. An experiment was designed using Sawtooth CBC Software. 326 students attempted the online survey. Utility values were derived by Hierarchical Bayes (HB) estimation and used to explain consumers' smartphone preferences. All the six attributes used for the study were found to significantly influence smartphone preference. Smartphone brand was the most important, followed by the price, camera, RAM, battery life, and storage. This study is one of the first to use Sawtooth CBC analysis to assess consumer smartphone preference based on the six attributes. We provide implications for the development of new smartphones based on attributes.

• Proceedings of the KIEE Conference
• /
• 1994.07b
• /
• pp.1603-1605
• /
• 1994

Recently, Gas Circuit Breakers are rapidly replacing Vacuum Circuit Breakers in the medium voltage switchgear. This is due to the improved performance of - GCB in interrupting capability, price, weight, size etc., while the countermeasure to suppress the switching surges of VCB has not been satisfactory. Intensive research works on the GCB have been conducted in the world widely since 1980. Nowadays it is well known that the thermal expansion type GCB can provide- better performance than puffer type in the distribution power system. KERI has conducted researches in the GCB rated at 25.8kV 25kA with Jinkwang Co. using the thermal expantion principle since 1993. In this paper, the calculated results of electric and magnetic fields for the model GCB are presented and analyzed. The effect of permanent magnet used to improve the interruption capabilty at the low current level is also investigated. The design parameters for the interrupter inspected through the short-circuit tests conducted at high power laboratory of KERI.

• THE INTERNATIONAL COMMERCE & LAW REVIEW
• /
• v.61
• /
• pp.165-190
• /
• 2014

The purpose of this study is to measure the trade insurance's macroeconomic effects by analyzing the causality between major economic variables(GDP per capita, market interest rate, inflation, unemployment rate, exchange rate) and trade insurance variable. I conducted empirical analyses using First-difference GMM(Generalized Method of Moments), System GMM and Panel-VAR Model, with panel data from 11 countries(Korea, United States, Japan, BRICs, Indonesia, Singapore, Hong Kong, Vietnam) between 1992 and 2011. There are several important findings. Above all, Trade insurance is positively and significantly related to GDP. This results show that trade insurance serves to increase economic growth. In other words, trade insurance leads to economic growth by helping increase GDP per capita. Especially, trade insurance negatively related to unemployment rate, it is for sure that trade insurance contribute to decrease unemployment rate. And trade insurance helps control of inflation. It is also confirmed that trade insurance contributes to price stability, which in turn serves to stabilize the overall economy. And this research finds as uncertainty in the market increases, seen it as increase of exchange rate, increasing trade insurance supply is stabilize the exchange rate.

• Journal of the Korea Safety Management & Science
• /
• v.10 no.1
• /
• pp.91-105
• /
• 2008

Nowadays, circulation industry is taking charge of important role in improvement of competitive power on the manufacturing industry and public welfare increase of consumer, price stabilization, employment creation and so on. A lot of research have been progressing for formation of total circulation complex, but decision making for selection of location on some facility is only calculated the optimum value when correct data values are inserted. However, a lot of decision making is accomplished in situation that have little knowledge of objective and constraints and as real world is also evaluated inclusive of analyst's subjectivity about variable, indefinite and fuzzy part, so it is decreasing a reliability on evaluation result and complicating objective evaluation on various effect and negative impact. Accordingly, from under like this situation, this study is to develop location decision model of circulation complex using fuzzy theory from the intention for the most reasonable decision making in fuzzy situation based on decision making problem on conventional location and size decision that did to be satisfactory constraints necessarily.

• The Journal of Bigdata
• /
• v.3 no.1
• /
• pp.13-20
• /
• 2018

Stock market prediction has been long dream for researchers as well as the public. Forecasting ever-changing stock market, though, proved a Herculean task. This study proposes a novel stock market sentiment lexicon acquisition system that can predict the growth (or decline) of stock market index, based on economic news. For this purpose, we have collected 3-year's economic news from January 2015 to December 2017 and adopted Word2Vec model to consider the context of words. To evaluate the result, we performed sentiment analysis to collected news data with the automated constructed lexicon and compared with closings of the KOSPI (Korea Composite Stock Price Index), the South Korean stock market index based on economic news.