• Proceedings of the Korean Information Science Society Conference
• /
• 2002.10e
• /
• pp.355-357
• /
• 2002

이동 컴퓨팅 환경에서는 무선 단말기 사용자의 이동에 따른 접속 단절 현상이 발생할 수 있다. 이러한 이동 컴퓨팅 환경에서 끊김 없는 핸드오프와 효율적인 호 수락 제어를지원하기 위해서 사용자의 이동성 예측이 중요하다. 따라서, 본 논문에서는 사용자의 이동성을 규칙적인 패턴과 임의적인 패턴으로 분류하고, 규칙적인 이동패턴을 예측하기 위하여 사용자의 과거 이동경로를 분석ㆍ압축하며 임의적인 이동패턴은 GPS의 정보를 이용하여 이동성을 예측한다. 이러한 예측 기법은 무선 단말기 사용자의 속도가 매우 빠르거나, 셀룰러망의 셀의 크기가 작은 경우에 보다 효율적으로 이동성을 예측할 수 있다는 장점이 있다.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
• /
• 2012.10a
• /
• pp.94-96
• /
• 2012

터미널의 경쟁력 제고, 터미널 생산성 향상이 중요한 요소라고 할 수 있다. 이러한 생산성에 영향을 줄 수 있는 요인은 다양하다. 그 중 야드 이송장비의 경우, 특정 선석크레인(QC, Quay Crane)에 야드 트랙터(YT, Yard Tractor)가 고정 할당되는 방식에서 다수 QC들의 작업을 처리하는 풀링 시스펨 방식으로 전환으로 터미널 생산성과 YT의 가용성을 높일 수 있다.

• Journal of Korean Society of Transportation
• /
• v.32 no.2
• /
• pp.93-105
• /
• 2014

This study evaluated the relative efficiency of mobile emission reduction countermeasures through a Data Envelopment Analysis (DEA) approach and determined the priority of countermeasures based on the efficiency. Ten countermeasures currently applied for reducing greenhouse gases and air pollution materials were selected to make a scenario for evaluation. The reduction volumes of four air pollution materials(CO, HC, NOX, PM) and three greenhouse gases($CO_2$, $CH_4$, $N_2O$) for the year 2027, which is the last target year, were calculated by utilizing both a travel demand forecasting model and variable composite emission factors with respect to future travel patterns. To estimate the relative effectiveness of reduction countermeasures, this study performed a super-efficiency analysis among the Data Envelopment Analysis models. It was found that expanding the participation in self car-free day program was the most superior reduction measurement with 1.879 efficiency points, followed by expansion of exclusive bus lanes and promotion of CNG hybrid bus diffusion. The results of this study do not represent the absolute data for prioritizing reduction countermeasures for mobile greenhouse gases and air pollution materials. However, in terms of presenting the direction for establishing reduction countermeasures, this study may contribute to policy selection for mobile emission reduction measures and the establishment of systematic mid- and long-term reduction measures.

• Journal of Korea Technology Innovation Society
• /
• v.19 no.4
• /
• pp.711-735
• /
• 2016

Drug Development is very important for promoting public health and pharmaceutical industry. There has been many studies on the efficiency of drug development, but there are few studies on the drug development R&D performed by government. Since CCR model assumes unidirectional influence of input and output, it is not appropriate to analyze the efficiency of R&D due to the time-lag and spill-over effect. Also, BBC model which assumes variable returns to scale has difficulty in deriving priorities between decision making units. Recently, Range Adjusted Measure (RAM) model has been suggested in R&D efficiency analysis. RAM model measures the efficincy by eliminating inefficiencies under variable returns to scale assumption, and its strong monotonicity enables to provide clear priorities between decision making units. In this study, we analyzed the efficiency of national R&D programs for drug development using the two-step approach, including RAM model and Tobit regression analysis, and discussed major policy implications.

• Journal of KIISE:Computer Systems and Theory
• /
• v.33 no.9
• /
• pp.615-625
• /
• 2006

Nonvolatile memory technology is evolving continuously and commercial products such as FeRAM and PRAM are now challenging their markets. As NVRAM has properties of both memory and storage, it can store persistent data objects while allowing fast and random access. To utilize NVRAM for general purpose storing of frequently updated data across power disruptions, some essential features of the file system including naming, recovery, and space management are required while exploiting memory-like properties of NVRAM. Conventional file systems, including even recently developed NVRAM file systems, show very low space efficiency wasting more than 50% of the total space in some cases. To efficiently utilize the relatively expensive NVRAM, we design and implement a new extent-based space-thrifty file system, which we call NEBFS (NVRAM Extent-Based File System). We analyze and compare the space utilization of conventional file systems with NEBFS and validate the results with experimental results observed from running the file system implementations on a system with actual NVRAM installed as well as on systems emulating NVRAM. We show that NEBFS has high space efficiency compared to conventional file systems.

• Journal of Technology Innovation
• /
• v.20 no.3
• /
• pp.29-55
• /
• 2012

In order to successfully adopt and implement the Balanced Scorecard(BSC), firms need to respond adequately to the rapid changes of today's business environment and consider the growing importance of non financial factors in the business activities such as intangible assets(R&D expenditure, patent, goodwill, etc.). Our primary focus throughout this paper is on developing Key Performance Index(KPI) of BSC for R&D expenditure activities. In this study, we have developed and named PEI(Patent Efficiency Index),which is the KPI for R&D expenditure by focusing on the efficiency of a patent that is the output from the R&D expenditures. Secondarily, we have attempted to address the solution for the current problems of the traditional R&D performance measurement by using our developed PEI and examine the usefulness and effectiveness of the newly developed our PEI. According to the empirical test results, we find that the PEI is positively associated with ROA and Tobin's Q, respectively and show that our developed PEI is more effective and accurate than the traditional R&D performance measurement as a business performance measurement. Furthermore, these findings proves that we can measure and evaluate how efficiently the firms perform the R&D activities and shows that the PEI can be a critical index for evaluating firm's business performance related to the R&D expenditures.

• Land and Housing Review
• /
• v.4 no.1
• /
• pp.33-42
• /
• 2013

This study which are recognized that the lack of empirical research about the efficiency of the elements of environmentally friendly housing development planned presented housing design elements and policies to revitalize for the reduction of greenhouse gas emissions by analyzing the effectiveness of reduction of greenhouse gas output. In addition, it used various models of DEA which are accepted until now effective technique to evaluate the performance of the organization. In conclusion, there are effective 5 regionals which are Seoul, Incheon, Ulsan, South Chungcheong Province, South Gyeongsang Province. other regionals was analyzed to be inefficient. The conclusion from this study are as follows: First, in case of 11 regionals which are analyzed to be inefficient, they have to difference plan elements to make up. So each region should establish strategy to complement vulnerability. Second, not only internal architectural factors but institutional, and external environmental factors also affect the reduction of greenhouse gas emissions. And weighted scores also were moderately high. But levels of weighted scores still less than the ratio of Good quality housing. So it can be determined that evaluation of individual architecture still considered important. It need to pay more attention to the operating system and the external environmental factors.

• Korea Trade Review
• /
• v.43 no.3
• /
• pp.1-26
• /
• 2018

This study estimates the technical efficiency and total factor productivity(TFP) of and analyzes the relationship between TFP and exports for Korean manufacturing companies from 2000 to 2016. Specially, TFP is decomposed into Technical Change(TC), Technical Efficiency Change (TEC), and Sale Effect(SE), and compared between large and small enterprises. First, in the case of technical efficiency, the Korean economy has been very vulnerable to external shocks, such as the sharp decline following the 2008 financial crisis. The efficiency of the electronics, automobile, and machinery sectors is low and needs to be improved. In addition, the technological efficiency of large enterprises is higher than that of SMEs in most manufacturing sub-sectors except for non-ferrous metals. In the case of TFP, most changes are due to TC, and the effective combination of labor, capital and the effect of scale have little effect, suggesting that improvement of internal structure is urgent. In addition, volatility due to the impact of the financial crisis in 2008 was much larger in SMEs than in large companies, so external economic impacts are more greater for SMEs than large enterprises. The relationship between TFP decomposition factors and exports shows that TC has a positive effect only on exports of SMEs. Therefore, in order to increase exports, in the case of SMEs, R&D support to promote technological development is needed. In the case of large companies, it is necessary to establish differentiated strategies for each export market, competitor company, and item to link efficiency and scale effect of exports.

• Ceramist
• /
• v.16 no.2
• /
• pp.42-49
• /
• 2013

기존의 Cd계 양자점에 비해 독성 문제가 적은 비 Cd계 양자점은 합성 공정과 발광 특성 제어의 난이도로 인해 아직 Cd계 양자점에 비해 응용성이 떨어지는 상태이다. 또한 기존의 형광체와 같이 쓰이거나 이를 대체하기 위해서는 온도에 따른 발광안정성 확보가 필요하지만, 아직은 전이금속 도핑된 II-VI족 양자점을 제외하면 쉽지 않은 실정이다. 그러나 핵-껍질 구조 형성, 표면처리 등 많은 연구를 통해 Cd계 양자점과 거의 동등한 발광효율을 얻을 수 있게 되었으며, 발광의 색순도를 표시하는 발광선폭 역시 Cd계 양자점에 상당히 근접하였다. 특히 BLU 응용을 위해서는 좁은 발광선폭이 필수적이며 조명용 백색 LED 응용을 위해서도 색순도가 높으며 발광효율이 우수한 적색 형광입자의 필요성이 크다. 대표적인 비 Cd계 양자점인 InP의 경우 공유결합성이 커서 합성 과정에 어려움이 있으며, 표면 제어가 쉽지 않으나 부단한 연구개발을 통해 40~50 nm까지 발광선폭을 줄였으며, 발광효율도 거의 100%에 육박하는 값을 얻은 바 있다. 향후 좀더 많은 연구개발을 통해 발광 안정성이 우수하고 색순도가 높은 고특성 비 Cd계 양자점의 개발이 이루어 지면 조명용 LED나 디스플레이의 고성능화를 실현시키는 중요한 소재가 될 것으로 기대한다.

• Proceedings of the Korean Information Science Society Conference
• /
• 2000.10c
• /
• pp.585-587
• /
• 2000

1994년 국내에 인터넷 붐이 일어나고 사용이 보편화되면서 전자메일은 개인간의 메세징을 가능하게 해주는 기반기술 중 하나로 자리잡고 있다. 기존의 POP(Post Office Protocol) 프로토콜을 이용하던 전자메일 시스템은 POP 프로토콜의 불편함을 제거한 별도의 세팅없이 지역, 언어, 시간에 제약이 없는 웹기반의 메세징 시스템이 등장하게 되었다. 현재 이러한 메세징 시스템에 사용되어지는 MTA(Mail Transper Agent)로는 sendmail을 거의 표준으로 받아 들여지고 있다. 그러나 sendmail은 단일 모듈로 작성되었으며 덩치가 매우 크고 보안상 문제점도 지적되고 있다. 이에 본 논문에서는 sendmail의 문제점을 효율적으로 해결할 수 있는 qmail의 활용방법을 제시하고 웹과 qmail을 연계할 수 있도록 자바를 통한 보안성, 안전성, 효율성이 강화된 인터넷 메세징 시스템을 설계 및 구현한다.