• Journal of KIISE:Computer Systems and Theory
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• v.31 no.5_6
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• pp.268-278
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• 2004

In this paper, we describe our experience in the design and implementation of the SMART file system to handle multimedia workload. Our work has three design objectives: (ⅰ) efficient support for sequential workload, (ⅱ) avoiding disk fragmentation, (ⅲ) logical unit based file access. To achieve these three objectives, we develop a file system where a file consists of linked list of Data Unit Group. Instead of tree like structure of the legacy Unix file system, we use single level file structure. Our file system can also access the file based upon the logical unit which can be video frame or audio samples. Data Unit Group is a group of logical data units which is allocated continuous disk blocks. At the beginning of each Data Unit Group, there exists an index array. Each index points to the beginning of logical data units, e.g. frames in the Data Unit Group. This index array enables the random access and sequencial access of semantic data units. SMART file system is elaborately tailored to effectively support multimedia workload. We perform physical experiments and compare the performance of SMART file system with EXT2 file system and SGI XFS file system. In this experiment, SMART file system exhibits superior performance under streaming workload.

• Journal of Korean Society of Environmental Engineers
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• v.35 no.2
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• pp.115-123
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• 2013

Stoker type incinerator is one of the most popular one used as municipal solid waste (MSW) incineration because, in general, it is quite suitable for large capacity and need no preprocessing facility. Nowadays, however, since the combustible portion of incoming MSW increases together with the decrease of the moisture content due to prohibition of directly burying food waste in landfill, the heating value of waste is remarkably increasing in comparison with the early stage of incinerator installation. Consequently, the increased heating value in incinerator operation causes a number of serious problems such as reduction of waste amount to be burned due to the boiler heat capacity together with the significant NO generation in high temperature environment. Therefore, in this study, a series of numerical simulation have been made as parameters of waste amount and the fraction of moisture in air stream in order to investigate optimal operating condition for the resolution of the problems associated with the high heating value of waste mentioned above. In specific, a detailed turbulent reaction flow field calculation with NO model was made for the full scale incinerator of D city. To this end, the injection method of moisturized air as oxidizer was intensively reviewed by the addition of moisture water amount from 10% and 20%. The calculation result, in general, showed that the reduction of maximum flame temperature appears consistently due to the combined effects of the increased specific heat of combustion air and vaporization heat by the addition of water moisture. As a consequence, the generation of NOx concentration was substantially reduced. Further, for the case of 20% moisture amount stream, the afterburner region is quite appropriate in temperature range for the operation of SNCR. This suggests the SNCR facility can be considered for reoperation. which is not in service at all due to the increased heating value of MSW.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.9 no.2
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• pp.171-177
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• 2016

Software reliability in the software development process is an important issue. Software process improvement helps in finishing with reliable software product. Infinite failure NHPP software reliability models presented in the literature exhibit either constant, monotonic increasing or monotonic decreasing failure occurrence rates per fault. In this study, reliability software cost model considering shape parameter based on life distribution from the process of software product testing was studied. The cost comparison problem of the Lomax distribution reliability growth model that is widely used in the field of reliability presented. The software failure model was used the infinite failure non-homogeneous Poisson process model. The parameters estimation using maximum likelihood estimation was conducted. For analysis of software cost model considering shape parameter. In the process of change and large software fix this situation can scarcely avoid the occurrence of defects is reality. The conditions that meet the reliability requirements and to minimize the total cost of the optimal release time. Studies comparing emissions when analyzing the problem to help kurtosis So why Kappa efficient distribution, exponential distribution, etc. updated in terms of the case is considered as also worthwhile. In this research, software developers to identify software development cost some extent be able to help is considered.

• 한국신재생에너지학회:학술대회논문집
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• 2010.11a
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• pp.143-143
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• 2010

GTL(Gas-to-Liquids)공정 중 합성가스 제조공정(Reforming Process)인 ATR(Auto-Thermal Reforming), SCR(Steam Carbon Reforming), POx(Partial Oxidation)의 시뮬레이션 연구를 수행하였다. Reforming 공정에서 생산된 합성가스는 GTL 합성유 제조공정인 FT(Fischer-Thropsch) 반응기로 주입되며, 합성유 생산에 최적의 효율을 보이는 H2/CO 비(합성가스에 포함된 반응물비)는 2.0으로 알려져 있다. FT공정은 합성가스를 원료로 고온 및 고압 반응을 거쳐 GTL 공정의 최종 생산품인 FT합성유를 제조하는 공정이다. 본 연구에서는 FT공정 효율 극대화를 위해 reforming 공정에서 생성되는 합성가스 내 H2/CO의 비를 2로 수렴토록 모사조건을 설정하였으며, 상기 조건을 만족하는 reforming 공정들의 운전 온도 및 feed 조성을 분석하고 비교하고자 한다. 현재 GTL 플랜트관련 산업계에 적용 혹은 주 연구대상인 reforming 공정으로는 ATR, SCR, POx 공정이 있다. ATR 공정은 $850{\sim}1100^{\circ}C$에서 메탄, 스팀 및 산소를 원료로 활용하여 H2 및 CO를 생산하는 공정으로 발열/흡열 반응이 상존하여 에너지 비용이 낮지만 공정구조 상 열회수설비 및 ASU(Air Separation Unit)이 필요하기에 CAPEX(초기설비 설치비용)가 높은 편이다. SCR공정은 CH4, Steam 및 CO2를 연료로 하기에 이산화탄소가 일정부분 포함된 가스전에도 적용이 가능하나 공정 운전 중 지속적으로 외부에서 열을 공급해야 하기에 에너지 투입비용이 높은편이며, 탄소침적의 문제가 있어 대용량 플랜트에는 적합하지 않다. POx공정은 약 $1,500^{\circ}C$의 고온에서 CH4가 O2에 의해 부분 산화되는 방식으로 촉매가 필요없어 설비비가 타 공정에 비해 저렴하나 생산가스의 H2/CO비가 다소 낮아 전체적인 GTL 공정효율이 저하되는 단점이 있다. 상기 세 공정은 GTL 산업계에서 실증 및 효율증대를 위해 주로 연구되는 공정이기에 본 연구의 분석대상으로 설정하였다. 본 연구에서는 상용공정모사기인 Aspen Plus를 활용하여 reforming 공정별로 FT합성공정의 최적 조건(H2/CO=2)을 만족하는 합성가스 생산조건 분석 및 비교를 수행할 예정이다. 운전조건인 공정 운전온도 및 feed 가스조성 등을 모사하기 위해 합성가스 reforming 공정을 모델링하고 공급유량 및 압력 등의 운전변수는 GTL국책과제 1단계 연구수행 결과를 토대로 선정하고자 한다. GTL공정의 경우, 설비의 운전조건이나 연료가스의 구성 및 유량에 따라 적합한 reforming 공정이 다르기에 본 시뮬레이션 결과를 향후 GTL 플랜트 공정모델 설계시 reforming 공정선정에 참고자료로 활용하고자 한다.

• Journal of the Institute of Electronics Engineers of Korea CI
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• v.46 no.6
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• pp.7-17
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• 2009

The precise analysis of exercise data for designing an effective rehabilitation system is very important as a feedback for planing the next exercising step. Many subjective and reliable research outcomes that were obtained by analysis and evaluation for the human motor ability by various methods of biomechanical experiments have been introduced. Most of them include quantitative analysis based on basic statistical methods, which are not practical enough for application to real clinical problems. In this situation, data mining technology can be a promising approach for clinical decision support system by discovering meaningful hidden rules and patterns from large volume of data obtained from the problem domain. In this research, in order to find relational rules between posture training type and muscle activation pattern, we investigated an application of the WAR(Weishted Association Rule) to the biomechanical data obtained mainly for evaluation of postural control ability. The discovered rules can be used as a quantitative prior knowledge for expert's decision making for rehabilitation plan. The discovered rules can be used as a more qualitative and useful priori knowledge for the rehabilitation and clinical expert's decision-making, and as a index for planning an optimal rehabilitation exercise model for a patient.

• Journal of the Korean Geographical Society
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• v.43 no.6
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• pp.961-980
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• 2008

It is usual to prioritize the blocks to rearrange residential environment by the responsible officer's intuition or a few specialist's experienced knowledge. The aim of this research was to evaluate rebuilding priority in the context of spatially weighted framework integrating resident's view. The spatial weighting for the variables related to evaluation of dwelling environment was derived from AHP (Analytic Hierarchy Process) approach through the analysis of resident's view. An empirical study for a case study site has been conducted to confirm the validity for the spatial weighting. The spatial weighting has frequently influenced in changing the rebuilding priority and was identified as the important predictor for the improvement sites of dwelling environment. The spatially weighted analysis made it possible to identify area-wide patterns of rebuilding priority area subject to many different type of thematic variables, which cannot be acquired by traditional field sampling. The spatially weighting derived by integrating various formats of spatial data into a comprehensive GIS database in particular, was ideally suited to displaying the objective distribution patterns for rebuilding priority. The result of this study would play a crucial role in dealing with public complaints for rebuilding priority since it could provide objective evidences in accordance with spatial weighting.

• Spatial Information Research
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• v.23 no.4
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• pp.13-22
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• 2015

There has been much interest in the VWorld open platform with the addition of a variety of contents or services such as 2D map, 3D terrain, 3D buildings, and thematic map since 2012. However, the VWorld system architecture was not stable for the system overload. For example, the system was stopped due to the rapidly increasing user accesses when the 3D terrain service of the North Korea and the Baekdu mountain was launched at September 2012 and September 2013, respectively. It was because the system architect has just extended the server system and the network bandwidth whenever the rapid increase of user accesses occurs or new service starts. Therefore, this study proposes a new VWorld system architecture that can reliably serve the huge volume of National Spatial Data by applying the new technologies such as CDN, visualization and clustering. Finally, it is expected that the results of this study can be used as a basis for the next VWorld system architecture being capable of a huge volume of spatial data and users.

• Journal of the Institute of Electronics Engineers of Korea CI
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• v.49 no.4
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• pp.31-41
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• 2012

The law enforcement agencies in the worldwide are confiscating or retaining computer systems involved in a crime/civil case, if there are any, at the preliminary investigation stage, even though the case does not involve a cyber-crime. They are collecting digital evidences from the suspects's systems and using them in the essential investigation procedure. It requires much time, though, to collect, duplicate and analyze disk images in general crime cases, especially in cases in which rapid response must be taken such as kidnapping and murder cases. The enterprise forensics, moreover, it is impossible to acquire and duplicate hard disk drives in mass storage server, database server and cloud environments. Therefore, it is efficient and effective to selectively collect only traces of the behavior of the user activities on operating systems or particular files in focus of triage investigation. On the other hand, if we acquire essential digital evidences from target computer, it is not forensically sound to collect just files. We need to use standard digital evidence container from various sources to prove integrity and probative of evidence. In this article, we describe a new digital evidence container, we called Xebeg, which is easily able to preserve collected digital evidences selectively for using general technology such as XML and PKZIP compression technology, which is satisfied with generality, integrity, unification, scalability and security.

• Journal of Digital Convergence
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• v.18 no.2
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• pp.277-284
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• 2020

Text mining is a representative method of big data analysis that extracts meaningful information from unstructured and large amounts of text data. Social media such as Twitter generates hundreds of thousands of data per second and acts as a one-person media that instantly and directly expresses public opinions and ideas. The traditional media are delivering informations, criticizing society, and forming public opinions. For this, we compare the responses of SNS with the responses of media on the issue of the termination of the Korea-Japan GSOMIA (General Security of Military Information Agreement), one of the domestic issues in the second half of 2019. Data collected from 201,728 tweets and 20,698 newspaper articles were analyzed by sentiment analysis, association keyword analysis, and cluster analysis. As a result, SNS tends to respond positively to this issue, and the media tends to react negatively. In association keyword analysis, SNS shows positive views on domestic issues such as "destruction, decision, we," while the media shows negative views on external issues such as "disappointment, regret, concern". SNS is faster and more powerful than media when studying or creating social trends and opinions, rather than the function of information delivery. This can complement the role of the media that reflects public perception.

• Economic and Environmental Geology
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• v.42 no.3
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• pp.273-282
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• 2009

To render more valuable information, a spatial database is being constructed from digitalized maps in the geographic areas. Transferring file-based maps into a spatial database, facilitates the integration of larger databases and information retrieval using database functions. Geological mapping is the graphical interpretation results of the geological phenomenon by geological surveyors, which is different from other thematic maps produced quantitatively. These features make it difficult to construct geologic databases needing geologic interpretation about various meanings. For those reasons, several organizations in the USA and Australia are suggesting the data model for the database construction. But, it is hard to adapt to a domestic environment because of the representation differences of geological phenomenon. This paper suggests the data model adaptive in domestic environment analyzing 1:50,000 scales of geologic maps and more detailed mine geologic maps. The suggested model is a logical data model for the ArcGIS GeoDatabase. Using the model it can be efficiently applicable in the 1:50,000 scales of geological maps. It is expected that the geologic data model suggested in this paper can be used for integrated use and efficient management of geologic maps.