• Journal of The Korean Association of Information Education
• /
• v.9 no.3
• /
• pp.453-462
• /
• 2005

Recently, due to technical improvements of storage devices and networks, the amount of data increase rapidly. In addition, it is required to find the knowledge embedded in a data stream as fast as possible. Huge data in a data stream are created continuously and changed fast. Various algorithms for finding frequent itemsets in a data stream are actively proposed. Current researches do not offer appropriate method to find frequent itemsets in which flow of time is reflected but provide only frequent items using total aggregation values. In this paper we proposes a novel algorithm for finding the relative frequent itemsets according to the time in a data stream. We also propose the method to save frequent items and sub-frequent items in order to take limited memory into account and the method to update time variant frequent items. The performance of the proposed method is analyzed through a series of experiments. The proposed method can search both frequent itemsets and relative frequent itemsets only using the action patterns of the students at each time slot. Thus, our method can enhance the effectiveness of learning and make the best plan for individual learning.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.12 no.3
• /
• pp.1341-1349
• /
• 2011

This research is focused on an analysis on the structure of RAW image file and the development of a RAW image file viewer for an embedded device. Recently, several RAW image file formats are being used for saving and displaying the images created by various DSLR cameras, and the necessity of handing RAW images in mobile multimedia devices is increasing. For the development of RAW image decoding/encoding library applicable to WinCE-based embedded devices viewer, an analysis of RAW image file formats, such as CRW, CR2, PEF, NEF, MRW, have been performed because their formats are not released in public. By using the library, the analysis software which can extract RAW image data, 2~3 JPEG image files and other informations such as the specification of a camera and various photographic parameters from RAW image files, were developped and a RAW image file viewer which can run in WinCE-based embedded devices. The experimental result has shown that the viewer could encode and decode RAW image files successfully and it took approximately 10secs to load them to the screen in S3C6410 based embedded platform. The outcomes of this research cloud be a good information and solution to multimedia application developers.

• Proceedings of the Korean Information Science Society Conference
• /
• 2004.10c
• /
• pp.631-633
• /
• 2004

본 논문에서는 유비쿼터스 홈 네트워킹 환경에서 사용자의 위치 이동을 실시간 추적하고 가정 내 주거 활동의 편의를 제공하는 정보가전기기들을 제어할 수 있는 능동형 홈 서비스 시스템을 제안한다. 본 시스템은 다계층의 분산시스템 환경으로 구성된다. 즉, 물리 센서와 정보가전기기 등이 존재하는 물리층과 유/무선 지원 인터넷/인트라넷 통신 플랫폼을 포함하는 시스템층, 그리고 물리적 장치들로부터 시스템층을 통해 들어오는 정보를 처리하는 응용층으로 구성되며 실 생활 공간 및 시간을 응용 시뮬레이션 환경으로 반영시킨다. 능동형 홈 서비스 시스템의 개발 목적은 실버아파트에서 독거노인의 위치기반 건강관리 정보 서비스 및 아파트 내 정보가전기기들의 맞춤형 제어를 제공하기 위함이다. 이와 같은 시스템을 구축하기 위해서는 홈 네트워크 내에서 사용자의 이동 위치를 파악하는 실시간 위치추적 기술과 정보가전기기들의 동작을 실시간 제어하기 위한 기술이 요구된다. 제안한 시스템에서는 UC at Irine의 DREAM Lab.에서 개발한 TMO(Time-triggered Message -triggered Objecl) 스킴을 적용하여 각 물리 센서와 정보가전기기들을 응용의 구성요소로 개발했다. 이를 통해 가정 내에 이동하는 TMO로 매핑된 이동객체를 추적하고 또한 홍 네트워크로 연결된 정보가전기기들을 정보가전 TMO 동작객체로 매핑하여 이들 사이의 능동적인 상호동작을 통해 맞춤형 서비스 및 실시간 제어가 가능하도록 했다. 마지막으로, 실시간 위치추적 및 정보가전제어 응용 시뮬레이션을 통해 능동형 홈 서비스 시스템을 구성하는 개별 동작객체들의 기능성과 수행성을 검증했다.황에 대하여 소개한다.이스는 실험정보가 저장된 데이터베이스, 분석결과가 저장된 데이터베이스, 그리고 유전자 정보 탐색을 위한 데이터베이스로 분류해 데이터를 효율적으로 관리할 수 있게 하였다. 본 시스템은 LiNUX를 운영체계로 하고 데이터베이스는 MYSQL로 하여 JSP, Perl. 통계처리 언어인 R로 구현되었다.프트웨어를 사용하지 않고도 국내의 순수 솔루션인 리눅스 기반의 LonWare 3.0 다중 바인딩 기능을 통해 저 비용으로 홈 네트워크 구성 관리 서버 시스템 개발에 대한 비용을 줄일 수 있다. 기대된다.e 함량이 대체로 높게 나타났다. 점미가 수가용성분에서 goucose대비 용출함량이 고르게 나타나는 경향을 보였고 흑미는 알칼리가용분에서 glucose가 상당량(0.68%) 포함되고 있음을 보여주었고 arabinose(0.68%), xylose(0.05%)도 다른 종류에 비해서 다량 함유한 것으로 나타났다. 흑미는 총식이섬유 함량이 높고 pectic substances, hemicellulose, uronic acid 함량이 높아서 콜레스테롤 저하 등의 효과가 기대되며 고섬유식품으로서 조리 특성 연구가 필요한 것으로 사료된다.리하였다. 얻어진 소견(所見)은 다음과 같았다. 1. 모년령(母年齡), 임신회수(姙娠回數), 임신기간(姙娠其間), 출산시체중등(出産時體重等)의 제요인(諸要因)은 주산기사망(周産基死亡)에 대(對)하여 통계적(統計的)으로 유의(有意)한 영향을 미치고 있어 $25{\sim}29$세(歲)의 연령군에서, 2번째 임신과 2번째의 출산에서 그리고 만삭의 임신 기간에, 출산시체중(出産時體重) $3.50{\

• KIPS Transactions on Software and Data Engineering
• /
• v.5 no.12
• /
• pp.623-634
• /
• 2016

Most of existing frequent pattern mining methods address time efficiency and greatly rely on the primary memory. However, in the era of big data, the size of real-world databases to mined is exponentially increasing, and hence the primary memory is not sufficient enough to mine for frequent patterns from large real-world data sets. To solve this problem, there are some researches for frequent pattern mining method based on disk, but the processing time compared to the memory based methods took very time consuming. There are some researches to improve scalability of frequent pattern mining, but their processes are very time consuming compare to the memory based methods. In this paper, we present PPFP as a novel disk-based approach for mining frequent itemset from big data; and hence we reduced the main memory size bottleneck. PPFP algorithm is based on FP-growth method which is one of the most popular and efficient frequent pattern mining approaches. The mining with PPFP consists of two setps. (1) Constructing an IFP-tree: After construct FP-tree, we assign index number for each node in FP-tree with novel index numbering method, and then insert the indexed FP-tree (IFP-tree) into disk as IFP-table. (2) Mining frequent patterns with PPFP: Mine frequent patterns by expending patterns using stack based PUSH-POP method (PPFP method). Through this new approach, by using a very small amount of memory for recursive and time consuming operation in mining process, we improved the scalability and time efficiency of the frequent pattern mining. And the reported test results demonstrate them.

• Korean Chemical Engineering Research
• /
• v.50 no.6
• /
• pp.1008-1014
• /
• 2012

The amount of domestic carbon dioxide emissions is more than 600 million tons/year. The emitted $CO_2$ should be captured and stored, however, suitable storage sites have not been found yet. A lot of researches on the conversion of captured carbon dioxide to useful carbon source have been conducted. The purpose of this study is to convert stable carbon dioxide to useful resources using less energy. For this purpose reducing gas and metallic oxide (activator) are required. Hydrogen was used as reducing gas and cobalt ferrite was used as activator. Considering that activator has different physical properties depending on synthesis methods, activator was prepared by hydrothermal synthesis and solid method. Decomposition characteristics of carbon dioxide were investigated using synthesized powders. Temperature programmed reduction/oxidation (TPR/TPO) and thermogravimetric analyzer (TGA) device were used to observe the decomposition characteristics of carbon dioxide. Activator prepared by solid method with 5 and 10 wt% CoO content showed an excellent performance. In TGA experiments with samples prepared by the solid method, reduction by hydrogen was 29.0 wt% and oxidation by $CO_2$ was highest in 27.5 wt%. 95% of adsorbed $CO_2$ was decomposed with excellent oxidation-reduction behaviors.

• Journal of Wetlands Research
• /
• v.22 no.4
• /
• pp.312-320
• /
• 2020

Various LIDs with natural water circulation function are applied to reduce urban environmental problems and environmental impact of development projects. However, excessive Infiltration and evaporation of LID facilities dry the LID internal soil, thus reducing plant and microbial activity and reducing environmental re duction ability. The purpose of this study was to develop a real-time measurement system with complex sensors to derive the management plan of LID facilities. The test of measurable sensors and Internet of Things (IoT) application was conducted in artificial wetlands shaped in acrylic boxes. The applied sensors were intended to be built at a low cost considering the distributed LID and were based on Arduino and Raspberry Pi, which are relatively inexpensive and commercialized. In addition, the goal was to develop complex sensor measurements to analyze the current state o f LID facilities and the effects of maintenance and abnormal weather conditions. Sensors are required to measure wind direction, wind speed, rainfall, carbon dioxide, Micro-dust, temperature and humidity, acidity, and location information in real time. Data collection devices, storage server programs, and operation programs for PC and mobile devices were developed to collect, transmit and check the results of measured data from applied sensors. The measurements obtained through each sensor are passed through the Wifi module to the management server and stored on the database server in real time. Analysis of the four-month measurement result values conducted in this study confirmed the stability and applicability of ICT technology application to LID facilities. Real-time measured values are found to be able to utilize big data to evaluate the functions of LID facilities and derive maintenance measures.

• Food Science and Preservation
• /
• v.12 no.4
• /
• pp.372-378
• /
• 2005

Compare with volatile organic compounds from unirradiated and irradiated dried-red pepper that is representative spice of korea. Volatile compounds from unirradiated and irradiated dried-red pepper were extracted using simultaneous distillation-extraction(SDE) apparatus and analyzed by Gas chromatography/mass spectrometer (GC/MS). A total of 61 and 62 compounds were identified from unirradiated and irradiated dried red pepper at dose of 10 kGy. These compounds included alcohols, aldehydes, furans, hydrocarbons, ketones, N-containing compounds, terpenes and micellaneous compounds. Furfural, benzaldehyde, linalool, nerolidol, ${\alpha}$-curcumene, ${\alpha}$-zingibirene were detected as the major volatile compounds from dried-red pepper. Specially, 1,3-bis[1,1-dimethylethyl]-benzene was confirmed as a marker of irradiated dried-red pepper because is not detected in unirraiatied dried-red pepper.

• The Journal of the Korea Contents Association
• /
• v.19 no.5
• /
• pp.187-193
• /
• 2019

Key-value storage engines are an essential component of growing demand in many computing environments, including social networks, online e-commerce, and cloud services. Recent key-value storage engines offer many features such as transaction, versioning, and replication. In a key-value storage engine, transaction processing provides atomicity through Write-Ahead-Logging (WAL), and a synchronous commit method for transaction processing flushes log data before the transaction completes. According to our observation, flushing log data to persistent storage is a performance bottleneck for key-value storage engines due to the significant overhead of fsync() calls despite the various optimizations of existing systems. In this article, we propose a group synchronization method to improve the performance of the key-value storage engine. We also design and implement a transaction scheduling method to perform other transactions while the system processes fsync() calls. The proposed method is an efficient way to reduce the number of frequent fsync() calls in the synchronous commit while supporting the same level of transaction provided by the existing system. We implement our scheme on the WiredTiger storage engine and our experimental results show that the proposed system improves the performance of key-value workloads over existing systems.

• Transactions of the Korean Society of Mechanical Engineers B
• /
• v.34 no.2
• /
• pp.121-127
• /
• 2010

The in-furnace desulfurization technique is applied to the $O_2/CO_2$ combustion system for the carbon capture and storage (CCS) process because this combustion system does not need an additional chamber for the desulfurization. $CaCO_3$ sorbent particles, which have a wide range in size from a few nanometers to several tens of micrometers, are used for this process. In this study, an experimental system which can simulate the $O_2/CO_2$ combustion system was developed. $CaCO_3$ sorbent particles were exposed to the high temperature reactor at $1200^{\circ}C$ with various residence times (0.33-1.46 s) in air and $CO_2$ atmospheric conditions, respectively. The sorbent particles were then sampled at the inlet and outlet of the reactor and analyzed qualitatively/quantitatively using SMPS, XRD, TGA, and SEM. The results showed that the residence time and atmospheric condition in a high temperature reactor can affect the characteristics of the $CaCO_3$ sorbent particles used in the in-furnace desulfurization technique, such as the calcination rate and reaction mechanism.

• Proceedings of the Korean Society for Agricultural Machinery Conference
• /
• 2017.04a
• /
• pp.86-86
• /
• 2017

마늘파종기는 파종기구동부와 파종후 파종홀의 복토역할을 하는 파종기롤러, 지면과의 마찰을 통해 바퀴의 회전토크가 발생하며 발생된 토크는 파종기 내부 동력으로 전달되어 전체 파종시스템(배종, 호퍼캠, 파종부)을 동작 시키는 기능을 수행하는 파종바퀴, 마늘종구를 한알씩 집어올려 중간이송컵으로 이송하는 자세교정컵이 포함된 배종부와 자세교정컵에서 낙하된 마늘종구를 땅속으로 파종하는 파종장치로 구성된다. 배종율 95%, 2립 배종률 5% 성능을 확보할 수 있는 기술이 개발될 경우 세계적으로도 독보적인 기술 우위를 확보할 수 있다. 이와 같은 기본적인 기능을 구현할 수 있는 컨셉모델에 대한 설계를 수행하여 시제품개발 전 기구해석과 구조해석 등을 위한 기본설계를 수행하였다. 배종율 95% 이상을 확보하기 위해서는 기존의 현장경험의 의한 설계 방식으로는 한계가 있기 때문에 시뮬레이션 및 분석 개발이 필요한데, 프레임은 고정밀 마늘종구 배종부 장착을 위한 기본 구조물로써 작동시 동력을 얻기 위한 바퀴와 연계가 되도록 설계되었으며, 호퍼는 배종 수행을 위해 마늘을 저장해 두는 통으로써 배종부와 연결된다. 배종부의 배종판이 회전함에 따라서 배종판의 홈이 호퍼 내로 들어갔다 나오면서 마늘을 집게되며, 동력 전달부는 배종판을 회전시켜주고, 회전 속도 조절을 가능하게 한다. 파종부는 배종부에서 중간컵을 통해 하나씩 공급해준 마늘을 땅에 심는 부분으로서. 프레임의 바퀴 회전과 연동되어 회전하고 설계하였다. 배종판에서 중간컵으로 이송된 마늘을 파종부의 파종컵에 받아 회전하면서 땅속에 파종컵이 묻히면 파종컵이 열리면서 땅속에 마늘을 심는 원리이다. 조간조정은 7조식의 경우 초기설치시 고정되도록 설계되었으며 농촌진흥청 기계화 표준재배안에 따라 의성마늘 기준 $14{\times}14cm$(조간${\times}$주간)를 기준으로 개발하였다. 조간조정은 기계가 설치되면 조정하기 어려우므로 14cm로 설계하였으며, 주간조정은 원형배종장치의 구동기어부의 속도비로 간격을 조정할 수 있도록 기어장치를 설계하였다. 주간조정은 13에서 18cm의 범위에서 작동하도록 설계되었으며, 필요에 따라 간격조절이 가능함. 마늘은 그 크기가 다르고, 형상도 다르기 때문에 종자에 따른 개별적인 파종기술들이 개발되어야하기 때문에 개발 기간이 오래 걸리고, 수익에 비하여 개발비가 과다하게 요구되는 실정인데 축적된 시뮬레이션 툴을 이용한 파종기 분석 기술을 확보할 경우 다른 파종기의 연구 개발에도 크게 도움이 될 것으로 기대되며, 생육측정 실험과 동역학 해석 툴 RecurDyn을 통해 파종기의 기구학적 분석을 통한 설계반영 인자를 도출할 계획이다.