• Title/Summary/Keyword: Call-Command

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Block Allocation Method for Efficiently Managing Temporary Files of Hash Joins on SSDs (SSD상에서 해시조인 임시 파일의 효과적인 관리를 위한 블록 할당 방법)

  • Joontae, Kim;Sangwon, Lee
    • KIPS Transactions on Computer and Communication Systems
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    • v.11 no.12
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    • pp.429-436
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    • 2022
  • Temporary files are generated when the Hash Join is performed on tables larger than the memory. During the join process, each temporary file is deleted sequentially after it completes the I/O operations. This paper reveals for that the fallocate system call and file deletion-related trim options significantly impact the hash join performance when temporary files are managed on SSDs rather than hard disks. The experiment was conducted on various commercial and research SSDs using PostgreSQL, a representative open-source database. We find that it is possible to improve the join performance up to 3 to 5 times compared to the default combination depending on whether fallocate and trim options are used for temporary files. In addition, we investigate the write amplification and trim command overhead in the SSD according to the combination of the two options for temporary files.

A Study on Learning and Teaching Environments for Computers and Mathematics Education ('컴퓨터와 수학교육' 학습-지도 환경에 관한 연구)

  • Kim, Hwa-Kyung
    • Journal of Educational Research in Mathematics
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    • v.16 no.4
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    • pp.367-386
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    • 2006
  • There are two strands for considering tile relationships between education and technology. One is the viewpoint of 'learning from computers' and the other is that of 'learning with computers'. In this paper, we call mathematics education with computers as 'computers and mathematics education' and this computer environments as microworlds. In this paper, we first suggest theoretical backgrounds ai constructionism, mathematization, and computer interaction. These theoretical backgrounds are related to students, school mathematics and computers, relatively As specific strategies to design a microworld, we consider a physical construction, fuctiionization, and internet interaction. Next we survey the different microworlds such as Logo and Dynamic Geometry System(DGS), and reform each microworlds for mathematical level-up of representation. First, we introduce the concept of action letters and its manipulation for representing turtle actions and recursive patterns in turtle microworld. Also we introduce another algebraic representation for representing DGS relation and consider educational moaning in dynamic geometry microworld. We design an integrating microworld between Logo and DGS. First, we design a same command system and we get together in a microworld. Second, these microworlds interact each other and collaborate to construct and manipulate new objects such as tiles and folding nets.

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A Design and Implementation of A Robot Client Middleware for Network-based Intelligent Robot based on Service-Oriented (지능형 네트워크 로봇을 위한 서비스 지향적인 로봇 클라이언트 미들웨어 설계와 구현)

  • Kwak, Dong-Gyu;Choi, Jae-Young
    • The KIPS Transactions:PartA
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    • v.19A no.1
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    • pp.1-8
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    • 2012
  • Network-based intelligent robot is connected with network system, provides interactions with humans, and carries out its own roles on ubiquitous computing environments. URC (Ubiquitous Robot Companion) robot has been proposed to develop network-based robot by applying distributed computing techniques. On URC robot, it is possible to save the computing power of robot client by environments, has been proposed to develop robot software using service-oriented architecture on server-client computing environments. The SOMAR client robot consists of two layers - device service layer and robot service layer. The device service controls physical devices, and the robot service abstracts robot's services, which are newly defined and generated by combining many device services. RSEL (Robot Service Executing Language) is defined in this paper to represent relations and connections between device services and robot services. A RESL document, including robot services by combining several device services, is translated to a programming language for robot client system using RSEL translator, then the translated source program is compiled and uploaded to robot client system with RPC (Remote Procedure Call) command. A SOMAR client system is easy to be applied to embedded systems of host/target architecture. Moreover it is possible to produce a light-weight URC client robot by reducing workload of RSEL processing engine.

Online Catalog Use Study in a University Library (대학도서관의 온라인목록 이용특성에 관한 연구 -덕성여자대학교를 중심으로-)

  • Yoo Jae-Ok
    • Journal of the Korean Society for Library and Information Science
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    • v.31 no.4
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    • pp.289-318
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    • 1997
  • The purpose of this study is to identify users behavioral characteristics for using the online catalog opened in May 1996 at Duksung Women's University Library. 278 student users were surveyed from October 4th to 8th in 1996. Major findings are as follows. 1. Most users$(87.4\%)$ prefer the online catalog to the card catalog and regard the online catalog easy to use$(89.6\%)$ 2. $(65.8\%)$ of users are active users who frequently use the online catalog at least 10 times or more per semester. 3. $10.4\%$ of users feel the online catalog difficult because they do not know how to use it. 4. Most users prefer the menu search mode among menu, command and fill-in-blank search modes offered by DISCOVER. The most preferred access points are the title for known-item search and subject headings for subject search. 5. User's attitude toward the online catalog is very favorable$(83.5\%)$, however, the search success rate is rather low $(77.0\%)$ compared to that of the card catalog $(87.0\%)$ 6. The title and author are regarded easy to use among access points offered by DISCOVER. Classification numbers and call numbers are the least easy access points to use. 7. Since users show lack of knowledge of how to use the online catalog, education and training programs on the online catalog use for users are needed. 8. Users showed different search patterns for pursuing different search goals. The most preferred access points are the title for known-item search and subject headings for subject search. These search behaviors are different from those in using the card for both the known-item search and subject search was the title.

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The Origin of Changseung and Ongjung Stone (장승의 기원과 옹중석)

  • Chung, Seung Mo
    • Korean Journal of Heritage: History & Science
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    • v.46 no.1
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    • pp.160-175
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    • 2013
  • There is the need to make a sharp distinction as regards JANGSEUNGs (Korean traditional totem poles) that are different in origin, history and function. This study is to identify the functions of the figures, as well as to trace stone JANGSEUNGs to their origins. In this regard, researched were conducted into the origins of JANGSEUNGs and their changes in history. There was a tradition in the GORYEO Dynasty (an ancient dynasty in the Korean Peninsula) that it erected JANGSAENGs (the archaic name of JANGSEUNGs) or allied stone figures within temples; especially, 'TONGDOSA GUKJANGSAENG SEOKPYO (a stone JANGSAENG that was erected by the royal command and is at the entrance of TONGDO Temple located in YANGSAN, South GYEONGSANG Province, South Korea)' functions as a stone monument rather than as a stone sign. In the engraved inscription, it is written that it should be erected in the form of PANA as before. 'PANA' refers to 'ZHONGKUI', a god in Chinese Taoism believed to exorcise devils that spread diseases. The inscription is to define the territory of TONGDO Temple. The article on HAN JUN GYEOM in a book 'WORAKGI (a travelogue on WORAK Mountain in North CHUNGCHEONG Province, South Korea)' written by HEO MOK makes it possible to guess the scale of GUKJANGSAENGs erected in DOGAP Temple. The stones, on which 'GUKJANGSAENG' or 'HWANGJANGSAENG' were engraved, are not JANGSAENGs but are demarcation posts. In the JOSEON Dynasty (the last dynasty in the Korean Peninsula) JANGSAENGs functioned as signposts. Unlike JANGSAENGs in temples, they were made of wood. At first, the word 'JANGSAENG' was written '長生' in Chinese characters, but in the JOSEON Dynasty another character '木 (wood)' was added to them, and thus the orthography was likely to change into 'JANGSEUNG.' In the JOSEON Dynasty, in addition, optative or geomantic figures were not called 'JANGSEUNG.' Historically, for instance, there has been no case where 'DOL HARBANGs (stone figures found only in JEJU ISLAND, South Korea)' are called 'JANGSEUNG.' In a book 'TAMRA GINYEON (a historical record on JEJU Island, South Korea)' it is written that KIM MONG GYU, JEJU governor, erected ONGJUNG Stones outside the fortress gate. ONGJUNG Stones usually refer to stone statues erected in front of ancient kings or dignitaries' mausoleums. Moreover, they were geomantic figures erected to suppress miasma. A magazine 'GWANGJUEUPJI (a journal on old GWANGJU, South Korea, 1899)' shows that two two ONGJUNG Stones were so erected that they might look at each other to suppress miasma from a pathway through which lucks lose. On the two stone figures located in BUAN-EUP, North JEOLLA Province, South Korea, inscriptions 'SANGWON JUJANGGUN' and 'HAWON DANGJANGGUN' were engraved. The words are to identify the figures' sexes. They are a kind of optative geomantic figures, and therefore there is no reason to call them 'JANGSAENG' or 'JANGSEUNG' or 'DANGSAN.' The words 'SANGWON' and 'HAWON' are closely associated with Taoism. Since then, the words have been widely used as inscriptions on stone figures in temples, and subsequently are used for JANGSEUNGs. A hatted ONGJUNG Stone, found in BUKANSAN Fortress, disappeared and other ones may be being buried somewhere. Meanwhile, ONGJUNG Stones in JEJU Island and stone figures in BUAN-EUP have hardly been displaced and thus have properly functioned. Stone figures, made in those days, seem to be most similar in function to JANGSAENGs made during the GORYEO Dynasty. Specifically, like earlier JANGSAENGs, stone figures made during the early to mid-18th century were likely to function not only as optative figures but as boundary stones. Most of stone figures in temples were made whenever the land use survey was conducted throughout the nation, but given that at the same period of time, the commonalty filed many lawsuits against grave sites, temples might erect many stone figures to mark their territories. Currently, wooden or stone figures are commonly called 'JANGSEUNG', but they were erected in different epochs and for different reasons. Their origins are to be sought in stone figures that functioned not only as optative figures in temples but as boundary stones during the GORYEO Dynasty.