• Educational Technology International
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• 제10권1호
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• pp.1-23
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• 2009

Learners are often posited in a paradoxical situation where they are not fully involved in decision making processes on how to learn, in designing their tools. Cognitive artifacts in e-learning are supposed to effectively support learner-centered e-learning. The purpose of the study is to analyze cases of cognitive artifacts and to inquire those design principles for facilitating the learner-centered e-learning. Four research questions are suggested: First, it will be analyzed the characteristics of learners with respect to design of cognitive artifacts for supporting the learner-centered e-learning. Second, characteristics of four cases to design cognitive artifacts in learner-centered e-learning environment are analyzed. Third, it will be suggested the appropriate design principles of cognitive artifacts to facilitating learner-centered learning in e-learning environment. Four cases of cognitive artifacts design in learner-centered e-learning was identified as follows: Wiki software as cognitive artifacts in computer-supported collaborative learning; 'Play Around Network (PAN)' as cognitive artifact to monitor learning activities in knowledge community; Knowledge Forum System (KFS) as a cognitive artifact in knowledge building; cognitive artifacts in Courses-as-seeds applied meta-design. Five design principles are concluded as follows: Promoting externalization of cognitive artifacts to private media; Helping learners to initiate their learning processes; Encouraging learners to make connections with other learners' knowledge building and their cognitive artifacts; Promoting monitoring of participants' contributions in collaborative knowledge building; Supporting learners to design their cognitive artifacts.

• Journal of Korean Neurosurgical Society
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• 제56권5호
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• pp.400-404
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• 2014

Objective : Clip artifacts limit the visualization of intracranial structures in CT scans from patients after aneurysmal clipping with cobalt alloy clips. This study is to analyze the parameters influencing the degree of clip artifacts. Methods : Postoperative CT scans of 60 patients with straight cobalt alloy-clipped aneurysms were analyzed for the maximal diameter of white artifacts and the angle and number of streak artifacts in axial images, and the maximal diameter of artifacts in three-dimensional (3-D) volume-rendered images. The correlation coefficient (CC) was determined between each clip artifact type and the clip blade length and clip orientation to the CT scan (angle a, lateral clip inclination in axial images; angle b, clip gradient to scan plane in lateral scout images). Results : Angle b correlated negatively with white artifacts (r=-0.589, p<0.001) and positively with the angle (r=0.636, p<0.001) and number (r=0.505, p<0.001) of streak artifacts. Artifacts in 3-D images correlated with clip blade length (r=0.454, p=0.004). Multiple linear regression analysis revealed that angle b was the major parameter influencing white artifacts and the angle and number of streak artifacts in axial images (p<0.001), whereas clip blade length was a major factor in 3-D images (p=0.034). Conclusion : Use of a clip orientation perpendicular to the scan gantry angle decreased the amount of white artifacts and allowed better visualization of the clip site.

• Imaging Science in Dentistry
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• 제49권3호
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• pp.219-228
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• 2019

Purpose: The aim of this study was to determine the reasons and solutions for intraoral phosphor storage plate (PSP) image artifacts and errors, and to develop an appropriate classification of the artifacts. Materials and Methods: This study involved the retrospective examination of 5,000 intraoral images that had been obtained using a phosphor plate system. Image artifacts were examined on the radiographs and classified according to possible causative factors. Results: Artifacts were observed in 1,822 of the 5,000 images. After examination of the images, the errors were divided into 6 groups based on their causes, as follows: images with operator errors, superposition of undesirable structures, ambient light errors, plate artifacts (physical deformations and contamination), scanner artifacts, and software artifacts. The groups were then re-examined and divided into 45 subheadings. Conclusion: Identification of image artifacts can help to improve the quality of the radiographic image and control the radiation dose. Knowledge of the basic physics and technology of PSP systems could aid to reduce the need for repeated radiography.

• 보존과학연구
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• 통권19호
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• pp.109-132
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• 1998

According to excavation of Imdang site, these sites were excavated place to a various of sites from Early lron period to the Koryo Kingdom. Artifacts to be conserved were excavated from A, D and E district. Metal artifacts were excavated from D and E district and lacquer ware artifacts were excavated from Adistrict. Metal artifacts including lacquer ware iron sword, imitative bronze mirror, Osujen and bronze artifact with letter and so on. Bronze artifacts were covered with soil and rust and performed consolidation after passivation treatment with Benzotriazole solution. Also, iron artifacts performed desalting treatment with 0.1M sesquicarbonate solution. After desalinization, adhesive of these artifacts were processed with Araldite(rapid type) after consolidation with20%∼30% NAD-10 solution. Lacquer ware artifacts remained fragments of lacquer to be all corroded and soiled. Therefore these artifacts retained its original form. Fragments of lacquer joined with Caparol 1%∼3% solution and the soil of relics coated with PSNY 3%∼6% solution. There were many kinds of lacquer were. Lacquer ware artifacts presumed to a string instrument that provide important clues for lacquer ware research. As for lacquer fragments inquire, paints grain size were $2∼5\mum$ and conformed to vanished three times.

• 대한방사선기술학회지:방사선기술과학
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• 제38권4호
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• pp.375-381
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• 2015

디지털 방사선 시스템은 영상의학에서 큰 비중을 차지하고 있다. 잘못된 영상이 제공 된다면 이는 환자의 건강에 나쁜 영향을 줄 수 있기에, 올바른 디지털 방사선 영상이 제공되어야만 한다. 또한, artifact는 오진으로 이어질 수 있다. 디지털 방사선 시스템에서 발생하는 artifact를 종류별로 분석하여 그 결과 분석하였다. 본 연구에서 사용된 artifact는 서울의 종합병원 급 의료기관에서 2007년부터 2014년까지 수집된 자료들이다. 수집된 자료는 발생 원인별로 구별하여 그 원인을 분석하였다. artifact는 하드웨어적 artifact, 소프트웨어적 artifact, 사용자 오류, 시스템 artifact 및 기타로 구분하였다. 하드웨어적 artifact는 Ghost가 가장 빈번하게 관찰되었으며, 이는 신호의 잔류에 의한 것이다. 다음은 RF 잡음에 의한 오류, 장비 내 이물질에 의한 오류 순이다. 소프트웨어 artifact는 많은 원인이 있다. 부정확한 영상 교정에 의한 artifact가 가장 많았으며, EDR 인식오류, 접합면 처리 오류 등이 있으며, 소프트웨어 artifact는 매우 다양한 경향을 나타낸다. 사용자 오류는 디지털 의료 영상 시스템을 바르게 이해하지 못해 발생시킨 것들이 많았다. 아울러, 시스템 artifact는 DICOM 헤더 정보 오류, 압축 오류가 있다. 분명하게 나타나는 artifact는 재촬영의 원인이 되어 환자의 피폭을 증가시키고, 불분명하게 나타나는 artifact는 오진을 유발 시킬 수 있다. 따라서 방사선사에게서 이러한 artifact를 바로 구별 할 수 있는 능력이 요구 된다. 그러므로 artifact가 발생되는 원인과 그 특성을 분명하게 이해함으로 지속적인 교육과 안정적인 시스템 운영에 힘써야 할 것으로 사료된다.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제10권3호
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• pp.1404-1415
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• 2016

Because of the properties of software such as invisibility, complexity, and changeability, software configuration management (SCM) for software artifacts generated during software life-cycle has been used for guarantee of the quality of the software. However, the existing SCM system has only focused on code artifacts and software development document artifacts such as Software Requirements Specification (SRS), Software Design Description (SDD), and Software Test Description (STD). Moreover, software research-oriented project comes out late the code artifacts and the software development document artifacts. Therefore, there is a need for trace and management of software research document artifacts composed of highly abstracted non-functional requirements like 'the purpose of the project', 'the objectives', and 'the progress' before generation of the code artifacts and the software development document artifacts for a long time. Nevertheless, the existing SCM system cannot trace and manage them. In this paper, we propose content-based configuration management system comprised of the relevance link generation phase and content-based testing phase to trace and manage them. The preliminary application results show applicability and feasibility of the proposed system.

• 대한의용생체공학회:의공학회지
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• 제30권6호
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• pp.476-481
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• 2009

The most troublesome artifacts in micro computed tomography (micro-CT) are ring artifacts. The ring artifacts are caused by non-uniform sensitivity and defective pixels of the x-ray detector. These ring artifacts seriously degrade the quality of CT images. In flat-panel detector based micro-CT systems, the ring artifacts are hardly removed by conventional correction methods of digital radiography, because very small difference of detector pixel signals may make severe ring artifacts. This paper presents a novel method to remove ring artifacts in flat-panel detector based micro-CT systems. First, the bad lines of a sinogram which are caused by defective pixels of the detector are identified, and then, they are corrected using a cubic spline interpolation technique. Finally, a ring artifacts free image is reconstructed from the corrected projections. We applied the method to various kinds of objects and found that the image qualities were much improved.

• 보존과학연구
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• 통권31호
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• pp.141-154
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• 2010

Many bronze artifacts have been excavated and preserved through conservation treatments in Korea but the analysis on artifacts was regarded as destruction of artifacts from the academic world of archaeology, Therefore, it is not so available to perform research on production techniques and provenances by with qualified analysis. Accordingly, there were only a few study cases about quality properties and production techniques But recently gradual change started to appear from the awareness of the need for the scientific approach to excavated artifacts. While Korean ancestors already had applied the different alloying ratios according to the use and shape of bronze artifacts, the analysis and study have been restrictedly performed. As a result, there was only a few analysis cases on a small minority of artifacts because they are the ancient relics, which made it hard to understand the bronze artifacts more deeply. This study researched into components rate, production techniques and hardness of bronze weapons such as a bronze sword and compared their alloying ratios with those of Chinese old records (周禮考工記, 金之六齊).

• 가정과삶의질연구
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• 제21권5호
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• pp.155-170
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• 2003

This paper will provide a basic analysis of traditional wedding artifacts as they appear on museum websites and their value for scientific research. The results of this study are as follows: 1. There were a total of 115 wedding artifacts(72 written documents related to weddings, 43 marital items) on the website of a museum. Most of them were related to the latter half of Cho-sun Dynasty. From these artifacts, we may understand the culture surrounding wedding during the transitional period from the Cho-sun Dynasty to modem time. 2. By analyzing such wedding artifacts, we can supplement existing methods of study such as literature research and case histories. In this way, we may better understand the history and culture of weddings. 3. In order to gain a deeper understanding of the culture of weddings we need to adopt a more interdisciplinary approach of wedding artifacts.

• 대한의용생체공학회:의공학회지
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• 제37권1호
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• pp.1-6
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• 2016

The biomedical information (heart rate, HRV, $SpO_2$ etc) from the Photoplethysmography (PPG) signal section can be estimated without the motion artifacts if the PPG signal section in the motion artifacts is detected accurately. But the PPG signal is easily exposed to the motion artifacts by the decrease of the medical instrument size and applying as portable or wearable. Besides, it is difficult to completely eliminate the motion artifacts from the PPG signal without distortion and ensure reliability as well. In this paper, the method was suggested to determine the motion artifacts or not on the PPG signal of the section divided into intervals of constant length. By comparing the spectrum of each section, it can be determined whether the motion artifacts are or not after obtaining the spectrum of each section by the Goertzel algorithm. Moreover, an amount of computation while maintaining a high detection rate can be reduced by using the Goertzel algorithm.