• The Korean Journal of Nuclear Medicine
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• v.38 no.1
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• pp.74-84
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• 2004

Purpose: Since I-125 emits low energy (27-35 keV) radiation, thinner crystal and collimator could be employed and, hence, it is favorable to obtain high quality images. The purpose of this study was to derive the optimized parameters of I-125 SPECT using a new simulation tool, GATE (Geant4 Application for Tomographic Emission). Materials and Methods: To validate the simulation method, gamma camera developed by Weisenberger et al. was modeled. Nal(T1) plate crystal was used and its thickness was determined by calculating detection efficiency. Spatial resolution and sensitivity curves were estimated by changing variable parameters for parallel-hole and pinhole collimator. Peformances of I-125 SPECT equipped with the optimal collimator were also estimated. Results: in the validation study, simulations were found to agree well with experimental measurements in spatial resolution (4%) and sensitivity (3%). In order to acquire 98% gamma ray detection efficiency, Nal(T1) thickness was determined to be 1 mm. Hole diameter (mm), length (mm) and shape were chosen to be 0.2:5:square and 0.5:10:hexagonal for high resolution (HR) and general purpose (GP) parallel-hole collimator, respectively. Hole diameter, channel height and acceptance angle of pinhole (PH) collimator were determined to be 0.25 mm, 0.1 mm and 90 degree. The spatial resolutions of reconstructed image of the I-125 SPECT employing HR:GP:PH were 1.2:1.7:0.8 mm. The sensitivities of HR:GP:PH were 39.7:71.9:5.5 cps/MBq. Conclusion: The optimal crystal and collimator parameters for I-125 Imaging were derived by simulation using GATE. The results indicate that excellent resolution and sensitivity imaging is feasible using I-125 SPECT.

• Korean Journal of Heritage: History & Science
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• v.34
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• pp.124-136
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• 2001

Among many different types of wares, we have amazing Sacred Water-pot(따르개, 注子) from Goryo-period(고리, 高麗, 918-1392). The stylistic peculiarity of Jung-Byoung(정병, 淨甁) is described in "Goryo-Dhogyoung, 고리도경, 高麗圖經", the classical design canon. It is said, "A sharpened mouth with narrow and prolonged neck is attached upon the broad mouth with thicker and even longer neck of the pot whose body intimates to the shape of melon." One could find this Jung-Byoung similar to the Indian drinking water jar, Kundika, which has been. even today, an everyday article in houses as well as in temples. In the early Buddhist cult, the object had been adopted as personal belonging of the Bodhisattvas(보살, 菩薩), especially of the Bodhisattva Avalokitesvara(관세음보살,觀世音菩薩). In short, the purifying character of water is met by the sacred ware to deliver the refreshing Sweet-Water(Holy-Water, 깨맑물, 단물, 단이슬물, 정수, 감로, 감로수, 성수, 淨水, 甘露, 甘露水, 聖水): For the holy purpose of fulfilling the thirst of people, of symbolozing the virtuous dharma. Thus, Ggamslkh-Byoung(깨맑병,淨水), the literal Korean name, denotes purifying and clarifying and clarifying water-pot to us. Among many other Asian countries, India, China, Korea, and Japan have a profound cult of the sacred water-pot(Ggamalkh-Byoung, Jung-Byoung, 깨맑병, 정병, 정수병, 감로병, 감로수병, 淨甁, 淨水甁, 甘露甁, 甘露水甁). Therefore, this charming holy object drew much attention not only from master artisans to shape and deliver them to people but also from painters and sculptors for their endowment of the sacred images dedicated to Buddha(부처,佛,佛陀). In China, the sacred water pot emerged in the period of Tang(당, 唐, 618~907)-Period and underwent much sophistication later on, I. e., from earthenware, ceramic-porcelain, bronze, and silver. However, the following represents a challenge to the well-known Goryo-Thangka(고리불화, 高麗佛畵) Painting of Bodhisattva Avalokitesvara to our speculation on the Sacred Water-pot(정병, 淨甁). The image suggests, when examined closely, that the Sacred Water-pot has been accompanied by, or placed in, a transparent glasswere(유리그릇) or crystalbowl(수정그릇)! We have no other physical proof of the existence of such a Holding-Bowl(받침그릇, 承盤), except for in this particular painting. This Holding-Bowl would have not been a mere elaboration on the practicality of controling the drips from the mouth of the pot. As in the chapter on Tang-ho(탕호, 湯壺), or thermal bowl, in the "Goryo-Dhogyoung" it advises readers that this style of bowl is to be filled with hot water, and thus function as a preserver of heat in the water inside the pot. As an offering to the Buddha, the Sacred Water-pot could have been used for serving him hot tea. Hence the sacred bottle is to contain the refreshing water, the water transcends to nectar, and the nectar is prepared as a nectar tea to offer the Buddha. For both the Holding-Bowl of Ggamalkh-Byoung(Jung-Byoung)and the Celestial-Robe(날개옷, 天衣) of the Bodhisattva Avalokitesvara, whose specified character is the Water-Moon(수월, 水月) in this particular Thangka(불화, 佛畵) painting, the transparency is essential. This is to refer to the purity and the lucid clarity of Bodhisattva Avalokitesvara and at a deeper level, to refer to the world of Buddhas-the Tushita(Paradise, Heaven, Eden, 극락, 불세계, 極樂, 佛世界). Howerver, without the discovery of an actual Holding-Bowl, accompanied by a Sacred Water-pot, such speculation will necessarily remain hypothetical. Nevertheless, there is an abundance of evidence of our ancient craftsmanship in jade and ctystal, dating back to the Bronze Age(1000~2B.C.) in Korea. By the time of the Three Kingdom-Period(삼국시대, 三國時代, 57B.C.~935A.D.), and especially the Silla(신라, 新羅, 57B.C.~935A.D.)-Empire, the jade and crystal ornamentation had become very intricate indeed. By the Goryo-Period(918~1392) and Chosun-Period(조선, 朝鮮,1392~1910),crystal-ware and jade art were popular in houses and Buddhist temples, whose master artsanship was heightened in the numerous Sarira-Cases(사리그릇, 舍利器), containing relics and placed inside Stupas(탑, 투, 搭)! Therefore, discovering a tiny part of the crystal or jade Holding-Bowl for the Sacred Water-pot and casting full light on this subject, would not be totally impossible. Lastly the present article shares the tiny hope for a sudden emergence of such a Holding-Bowl.

• The Korean Journal of Nuclear Medicine Technology
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• v.14 no.2
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• pp.33-37
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• 2010

Purpose: In the early stage of using PET/CT, it was used to damper revision but recently shows that CT with MDCT is commonly used and works well for an anatomical diagnosis. This hospital makes the accuracy and convenience more higher in the diagnosis and evaluate of coronary heart disease through concurrently running myocardial perfusion SPECT examination, myocardial PET examination with FDG, and CT coronary artery CT angiography(coronary CTA) used PET/CT with 64-slice. This report shows protocol and image based on results from about 400 coronary heart disease examinations since having 64 channels PET/CT in July 2007. Materials and Methods: An Equipment for this examination is 64-slice CT and Discovery VCT (DVCT) that is consisted of PET with BGO ($Bi_4Ge_3O_{12}$) scintillation crystal by GE health care. First myocardial perfusion SPECT with pharmacologic stress test to reduce waiting time of a patient and get a quick diagnosis and evaluation, and right after it, myocardial FDG PET examination and coronary CTA run without a break. One-stop evaluation protocol of ischemic heart disease is as follows. 1)Myocardial perfusion SPECT with pharmacologic stress: A patient is injected with $^{99m}Tc$-MIBI 10 mCi and does not have any fatty food for myocardial PET examination and drink natural water with ursodeoxcholic acid 100 mg and we get SPECT image in an hour. 2)Myocardial FDG PET: To reduce blood fatty content and to increase uptake of FDG, we used creative oral glucose load using insulin and Acipimox to according to blood acid content. A patient is injected with $^{18}F$-FDG 5 mCi for reduction of his radiation exposure and we get a gated image an hour later and get delay image when we need. 3) Coronary CTA: The most important point is to control heart rate and to get cooperation of patient's breath. In order to reduce a heart rate of him or her below 65 beats, let him or her take beta blocker 50 mg ~ 200 mg after a consultation with a doctor about it and have breath-practices then have the examination. Right before the examination, we spray isosorbide dinitrate 3 to 5 times to lower tension of bessel wall and to extension a blood wall of a patient. It makes to get better the shape of an anatomy. At filming, a patient is injected CT contrast with high pressure and have enough practices before the examination in order to have no problem. For reduction of his radiation exposure, we have to do ECG-triggered X-ray tube modulation exposure. Results: We evaluate coronary artery stenosis through coronary CTA and study correlation (culprit vessel check) of a decline between stenosis and perfusion from the myocardial perfusion SPECT with pharmacologic stress, coronary CTA, and can check viability of infarction or hibernating myocardium by FDG PET. Conclusion: The examination makes us to set up a direction of remedy (drug treatment, PCI, CABG) because we can estimate of effect from remedy, lesion site and severity. In addition, we have an advantage that it takes just 3 hours and one-stop in that all of process of examinations run in succession and at the same time. Therefore it shows that the method is useful in one stop evaluation of ischemic heart disease.

• Journal of Advanced Navigation Technology
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• v.14 no.3
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• pp.452-458
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• 2010

In case of an embedded system with computing resource restrictions such as system power and cpu, the overhead due to displaying data on the computer screen may have a significant influence on the system performance. This paper describes an initialization method for LCD-driving components such as an ARM Core, an LCD controller, and an SPI(serial peripheral interface). It also introduces a pixel display function and a panel display method using virtual screen for reducing the display overhead for an LN2440SBC system with an ARM9-based S3C2440A microprocessor. A virtual screen is a large space of computer memories allocated much larger than those needed for one-time display of an image. Displaying a specific region of a virtual screen is done by assigning it as a view-port region. Such a display is useful in an embedded system when concurrently running tasks produce and display their respective results on the screen; it is especially so when the execution result of each task is partially modified, instead of being totally modified, on its turn and displayed. If the tasks running on such a system divide and make efficient use of the region of the virtual screen, the display overhead can be minimized. For the performance comparison with and without using the virtual screen, two different images are displayed in turn and the amount of time consumed for their display is measured. The result shows that the display time of the former is about 5 times faster than that of the latter.

• Journal of the Korean Vacuum Society
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• v.22 no.5
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• pp.250-256
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• 2013

It is described that the proton beam induces micro-size defects and electronic deep levels in luminescence Thin Film. Coincidence Doppler Broadening Positron Annihilation Spectroscopy (CDBPAS) and Positron lifetime Spectroscopy were applied to study of characteristics of a poly crystal samples. In this investigation the numerical analysis of the Doppler spectra was employed to the determination of the shape parameter, S-parameter value. The samples were exposed by 3.0 MeV proton beams with the intensities ranging between 0 to ${\sim}10^{14}$ particles. The S-parameter values decreased as increased the proton beam, that indicates the protons trapped in vacancies. Lifetime ${\tau}_1$ shows that positrons are trapped in mono vacancies. Lifetime ${\tau}_2$ is not changed according to proton irradiation that indicate the cluster vacancies of the grain structure.

• Journal of Conservation Science
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• v.27 no.2
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• pp.223-229
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• 2011

Buddha painting cultural properties couldn't avoid the change of colors and the exfoliation phenomenon by the characteristic of material and environmental factors. Especially, because in the beginning of the fine crack and the decoloration phenomenon on the surface of pigment would be significantly decrease stability of the whole object, it is necessary to take particular measure. Therefore, this is a study on conservation of Avalokitesvara in Potalaka in Hyeondeungsa in Gapyeong. It treated damaged parts of the object, carried out backing papers and matching colors. And then, it examined scientific analysis of pigments. Also, it performed nondestructive testing like XRF, FT-IR, and image microscope to investigate the quality of the material of hanji using the object and the component and characteristic of pigments. As a result, FT-IR spectrum matching Korean traditional paper(hanji) was detected in hanji of Avalokitesvara in Potalaka in Hyeondeungsa. The black pigment making a thin layer over the white pigment would estimate carbon compounds of unconfirmed ink stick or soot as XRF and FT-IR. Also, the white pigment was lead white($PbCO_3{\cdot}Pb(OH)_2$) involving Pb(Lead) and a carbonate. It was observed that the crystal of blue pigment had the different sizes of the particles from the microscope. In the case of this blue pigment, it showed cobalt blue and lead white was mixed when it used because both Cu and Pb were highly detected in XRF data.

• Korean Journal of Optics and Photonics
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• v.15 no.4
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• pp.299-308
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• 2004

We proposed more efficient encoding methods that can design a multi-channel multi-level phase only computer-generated hologram(CGH) that can reconstruct many objects simultaneously without a conjugate image. We used a fabrication technique for the pixel oriented CGH for designing the pattern of the proposed multi-channel CGH. We investigated the difference of the optical efficiency(η), mean square error(MSE) and signal-to-noise ratio(SNR) of multi-channel CGHs that were designed by three kinds of encoding methods according to the number of quantization phase levels, and we estimated the performance of the pattern of the proposed multi-channel CGH. Generally, as the number of input objects' reference patterns stored in the CGH is increased, the reconstruction quality of the CGH is degraded. But we observed through computer simulation that the diffraction efficiency of the 1-ch CGH is 70%, and those of the 2-ch, 4-ch, 8-ch CGHs are 62%, 62% and 63%. Therefore we found that the diffraction efficiencies of the multi-channel CGHs using the newly proposed encoding method are similar to that of 1-ch CGH. We implemented the CGH optically using a liquid crystal spatial light phase modulator that consisted of a PAL-SLM efficiently coupled with a XGA type LCD by an optical lens and an LD for illuminating the LCD. We discussed the output images that are reconstructed from the PAL-SLM.

• Journal of the Korean Ceramic Society
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• v.34 no.1
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• pp.31-36
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• 1997

The effects of 0 to 10mol% excess MgO addition on the microstructure and dielectric properties in 30Pb(Mg1/3Nb2/3)O3-20PbTiO3-50Pb(Mg1/2W1/2)O3 ternary system were investigated. Samples were prepared by mixed oxide and precursor methods to compare the role of excess MgO. Excess MgO enhanced grain growth and increased dielectric constant. The dielectric constant and tesmperature dependence of dielectric constant of the sample sintered at 100$0^{\circ}C$ with 5mol% MgO were above 5,000 and +25% to -50% from - 55$^{\circ}C$ to 1$25^{\circ}C$, respectively. For these specimens the phases percent were mainly perovskite and Pb2WO5, which was confirmed by XRD analysis. Also the amount of cubic pyrochlore Pb3Nb4O13 and PbWO4 were de-creased with sintering temperature and MgO addition. BSE image showed the chemical inhomogeneous dis-tribution. Crystal phase formed at each sintering temperature and the chemical inhomogeneous distribution caused the decrease of the temperature dependence of dielectric constant.

• Journal of the Institute of Electronics and Information Engineers
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• v.53 no.5
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• pp.143-151
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• 2016

The aim of this study is to investigate the optimal algorithm to extract medical radiation induced pixel signal from complementary metal-oxide semiconductor (CMOS) sensors of smartphones camera. The pixel intensity and pixel number of smartphone camera were measured as the X-ray dose was increased. The front camera of the smartphone camera has low noise property and excellent dose response as compared to the back camera of the smartphone. The indirect method which uses scintillation crystal in front of the smartphone camera, couldn't improve the X-ray detection efficiency as compared to the direct method which does not use any scintillator in front of the smartphone camera. When we used the algorithm which employing threshold level on the pixel intensity and pixel number, the dose linearity was more higher for the pixel intensity rather for the pixel number. The use of pixel intensity of Y color component which represents the grey scale, would be efficient in terms of the radiation detection efficiency and reducing the complexity of the image processing. We expect that the radiation dose monitoring can be managed effectively and systematically by using the proposed radiation detection algorithm, thus eventually will contribute to the public healthcare.

• Journal of the Korean Vacuum Society
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• v.1 no.1
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• pp.67-72
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• 1992

The growth of Ti on Si(111)-$7{\times}7$ and the formation of epitaxial C54 $TiSi_2$ were investigated by using reflection high energy electron diffraction(RHEED) and high resolution transmission electron microscopy(HRTEM). Polycrystalline Ti layer is grown on the amorphous Ti-Si interlayer which is formed at the Ti/Si interface by Ti deposition on Si(111)-$7{\times}7$ at room temperature (RT). HRTEM lattice image and transmission electron diffraction(TED) showed that epitaxial C54 $TiSi_2$ grown on Si substrate with 160 ML of Ti on Si(111)-$7{\times}7$ surface at RT, followed by annealing at $750^{\circ}C$ for 10 min in UHV. Thin single crystal Si overlayer with [111] direction is grown on $TiSi_2$ surface when $TiSi_2$/Si(111) is annealed at ${\sim}900^{\circ}C$ in UHV, which was confirmed by Si(111)-$7{\times}7$ superstructure.