• Imaging Science in Dentistry
• /
• v.51 no.2
• /
• pp.93-106
• /
• 2021

Purpose: This study was conducted to review the literature regarding the types of cone-beam computed tomography (CBCT) artifacts around dental implants and the factors that influence their formation. Materials and Methods: A search strategy was carried out in the PubMed, Embase, and Scopus databases to identify published between 2010 and 2020, and 9 studies were selected. The implants included 306 titanium, titanium-zirconium, and zirconia implants, as well as 5 titanium cylinders. Results: The artifacts around the implants were the beam-hardening artifact, the streaking artifact, and band-like radiolucent areas. Some factors that influenced the formation of artifacts were the implant material, bone type, evaluated regions, distance, type of CBCT, field of view (FOV) size, milliamperage, peak kilovoltage (kVp), and voxel size. The beam-hardening artifact was the most widely reported, and it was minimized in protocols with a smaller FOV, larger voxels, and higher kVp. Conclusion: The risk and benefit of these protocols in individuals with dental implants must be considered, and clinical examinations and complementary radiographs play an essential role in implantology.

• Journal of Platform Technology
• /
• v.11 no.1
• /
• pp.11-22
• /
• 2023

Various video conferencing and collaboration applications have emerged due to the global epidemic of new viral infections. In addition to real-time video conferencing, video conferencing applications provide features such as chat and file sharing on various platforms. Because various personal information is stored through functions such as chatting, file and screen sharing, these video conferencing applications are the major target of analysis from a digital forensic investigation. In the case of applications that provide cross-platform, the form of stored data is different depending on the platform. Therefore, to utilize data of video conferencing application for forensic investigation, preliminary research on artifacts stored by platform is required. In this paper, we used the video conferencing applications GoToWebinar and GoToMeeting and analyzed the artifacts generated. As a result, we list the main data from a digital forensic investigation. We identify data stored for each platform provided by GoToWebinar and GoToMeeting and organize artifacts that can estimate user behavior. Also, we classify the data that can be acquired according to the role and environment within the video conference.

• Investigative Magnetic Resonance Imaging
• /
• v.5 no.1
• /
• pp.38-42
• /
• 2001

Dark band artifacts are often observed in angiograms of arteries obtained by 2D time-of-flight (TOF) angiography with saturation of veins by presaturation RF pulses. At some arteries the arterial blood velocity varies in a triphasic pattern during a cardiac cycle. The arterial blood, that is saturated by presaturation RF pulses in the saturation band, can flow back into the imaging slice during the retrograde flow phase of the triphasic variation. When such saturated retrograde flow occurs during the acquisition of the central part of the K space, a signal void can result in base images and consequently dark band artifacts can appear in angiograms. This phenomenon is experimentally demonstrated by varying the gap between the imaging slice and the saturation band. Furthermore, a new pulse sequence is proposed to eliminate the dark band artifacts by changing the profile of the saturation band front a rectangle to a ramp.

• Journal of Conservation Science
• /
• v.21
• /
• pp.5-20
• /
• 2007

The stone artifacts in Bronze age from the Hyocheon sites in the Gwangju, Korea were studied on the basis of material characteristics and provenance presumptions. The use and rock names of the artifacts are a stone shovel by andesite, the stone grinding pestle by pyrophyllite, the stone sickle by schist and four stone semifinished artifacts by slates. Andesitic stone shovel could be observed easily around the Hyocheon relic site. But, rocks of the stone grinding pestle, the stone sickle, the stone arrowhead and the stone semifinished artifacts could be confirmed typical occurrences of the all kinds of rocks around the Hwasun coal mine area above 10km from the site. These are made the coupled samples with each stone artifact to the same kinds of raw material rocks based on analysis of the lithology and geochemistry. As a result a geochemical evolution trends of both a stone artifact and the rock showed very similar patterns based on normalization using the behavior, enrichment, compatibility and incompatibility of the elements. Therefore, the source rock of the stone shovel was convey from Mudeung mountain possible interpreted that the domestic-type artifacts are distributed in the vicinity of the Hyocheon site. On the other hand, the stone grinding pestle, the stone sickle, the stone arrowhead and the stone semifinished artifacts were convey from the Hwasun coal mine area possible foreign-type stone artifacts interpreted that the source rocks. Consequently, in the foreign-type stone artifacts are should archaeologic research which it can examine various possibilities clearly that the possibility to coming the introduction with the mankind migration, diffusion to dealings of tribe, the captured enemy equipment through the war and the trade with the behavior of the materials.

• Korean Journal of Heritage: History & Science
• /
• v.53 no.1
• /
• pp.24-33
• /
• 2020

In excavated bronze artifacts, corrosion products of various shapes and colors are observed due to multiple corrosion factors coexisting in the burial environment, and these corrosion products can constitute important data not only in terms of long-term corrosion-related information, but also in connection with preservation of artifacts. As such, scientific analysis is being carried out on the corrosion layer and corrosion products of bronze artifacts, and the corrosion mechanism and the characteristics of corrosion products elucidated, which is essential for interpreting the exposed burial environment and its association with corrosion factors inside the burial environment. In this study, after classifying excavated bronze artifacts according to alloy ratio and fabrication technique, comprehensive analysis of the surface of corrosion artifacts, corrosion layer, and corrosion products was carried out to investigate the corrosion mechanism, formation process of the corrosion layer, and characteristics of corrosion products. The study designated two groups according to alloy ratio and fabrication technique. In Group 1, which involved a Cu-Sn-Pb alloy and had no heat treatment, the surface was rough and external corrosion layers were formed on a part, or both sides, of the inside and the outside, and the surface was observed as being green or blue. α+δ phase selection corrosion was found in the metal and some were found to be concentrated in an empty space with a purity of 95 percent or more after α+δ phase corrosion. The Cu-Sn alloy and heat-treated Group 2 formed a smooth surface with no external corrosion layer, and a dark yellow surface was observed. In addition, no external corrosion layer was observed, unlike Group 1, and α corrosion was found inside the metal. In conclusion, it can be seen that the bronze artifacts excavated from the same site differ in various aspects, including the formation of the corrosion layer, the shape and color of the corrosion products, and the metal ion migration path, depending on the alloy ratio and fabrication technique. They also exhibited different corrosion characteristics in the same material, which means that different forms of corrosion can occur depending on the exposure environment in the burial setting. Therefore, even bronze artifacts excavated from the same site will have different corrosion characteristics depending on alloy ratio, fabrication technique, and exposure environment. The study shows one aspect of corrosion characteristics in specific areas and objects; further study of corrosion mechanisms in accordance with burial conditions will be required through analysis of the corrosive layer and corrosive product characteristics of bronze artifacts from various regions.

• Journal of Korean Society for Atmospheric Environment
• /
• v.23 no.1
• /
• pp.74-83
• /
• 2007

Artifacts due to inter-particle and gas-particle interactions during PM2.5 sampling were quantified by comparing the measurement results between the annular denuder-filterpack system and the filterpack system without denuder. Measurements were carried in Seoul for 10 days in each season; Nov. 2004, Jan. 2005, Mar. 2005, and Jul. 2005, respectively. In each day, two 12-h samples were obtained. The concentrations of nitrate and chloride showed seasonal variations mainly due to the availability of ammonium to neutralize nitrate or chloride. Nitrates and chloride losses were prominent in summer. Since most of ammonia was used to neutralize sulfuric acid and formed ammonium sulfate in summer, nitrate and chloride could not exist in particles and ammonium loss was smaller than other seasons.

• Analytical Science and Technology
• /
• v.11 no.4
• /
• pp.316-320
• /
• 1998

An image analysis was used for the interpretation of microstructures of ferrous metal artifacts. For the purposes, various microstructural features such as average grain size, phase area, shape factor, and composition of the inclusions, were parameterized for the information about manufacturing techniques such as casting, heating and tempering. The carbon content was determined through the evaluation of the amount of pearlite phase. As the amount of pearlite phase increased the shape factor also increased. Grain size was relatively smaller in trans-section than in cross-section. The manufacturing direction was trans-sectional because the orientation of inclusions was elongated lengthwise. All inclusions was of silicate groups and the manufacturing temperature was estimated up to $1450^{\circ}C$.

• Journal of the Korea Furniture Society
• /
• v.20 no.6
• /
• pp.605-611
• /
• 2009

This paper reports the application of radiocarbon wiggle matching for Korean wooden artifacts such as furniture and Buddhist statues for precise dating. Ten biannual samples of 20 years (AD 1249-1268) for AMS (accelerator mass spectrometry) radiocarbon measurements were prepared from a board of the pedestal for Buddhist statue at Jeongsusa (temple) in Kangwhado, Korea, which was dendrochronologically dated. The average 95.4% confidence interval of radiocarbon dating without wiggle matching was 123 year. When wiggle matching technique was applied, it became 37 year, 3.3 times smaller than that without wiggle matching. The results indicated that wiggle matching technique using the calibration curve for northern hemisphere (IntCal04: International radiocarbon calibration curve announced in 2004) can produce precise dates for Korean wooden artifacts which possess as much as 20 tree rings.

• Applied Microscopy
• /
• v.35 no.1
• /
• pp.1-13
• /
• 2005

Fine photographs are essential in the electron microscopy. Artifacts can be introduced during all steps of electron microscopy; specimen processing, observation and printing. Every caution is necessary to avoid the artifact formation. In this review, the authors discussed the causes of various artifacts and suggested the solution to help the correct tissue handling and electron microscopic observations.

• Proceedings of the Korean Information Science Society Conference
• /
• 2010.06a
• /
• pp.242-243
• /
• 2010

Reducing compression artifacts such as ringing and blocking is one of important issues to improve a visual quality of a JPEG compressed image. In this paper, we propose a new post processing technique based on bilateral filtering (BF), which is one of the techniques that are used to reduce compression artifacts. An important issue with the application of the BF is the selection of the filter parameters, which affects the result significantly. In this work, we suggest a new method to select the filter parameter automatically. In addition to artifact reduction using the BF, a contrast enhancement is performed to overcome the contrast loss problem due to compression. The experimental result shows that the proposed approach can alleviate the artifacts efficiently.