• 대한방사선기술학회지:방사선기술과학
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• 제45권2호
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• pp.127-134
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• 2022

In order to overcome the image quality limitations of the conventional C-arm, a flat panel detector (FPD) is used to enhance spatial resolution, detective quantum efficiency, frame rate, and dynamic range. Three-dimensional (3D) visualized information can be obtained from C-arm computed tomography (CT) equipped with an FPD, which can reduce patient discomfort and provide various medical information to health care providers by conducting procedures in the interventional procedure room without moving the patient to the CT scan room. Unlike a conventional C-arm device, a C-arm CT requires different basic safety and essential performance evaluation criteria; therefore, in this study, basic safety and essential performance evaluation criteria to protect patients, medical staff, and radiologists were derived based on International Electrotechnical Commission (IEC) standards, the Ministry of Food and Drug Safety (MFDS) standards in Korea, and the rules on the installation and operation of special medical equipment in Korea. As a result of the study, six basic safety evaluation criteria related to electrical and mechanical radiation safety (leakage current, collision protection, emergency stopping device, overheating, recovery management, and ingress of water or particulate matter into medical electrical (ME) equipment and ME systems: footswitches) and 14 essential performance evaluation criteria (accuracy of tube voltage, accuracy of tube current, accuracy of loading time, accuracy of current time product, reproducibility of radiation output, linearity and consistency in radiography, half layer value in X-ray equipment, focal size and collimator, relationship between X-ray field and image reception area, consistency of light irradiation versus X-ray irradiation, performance of the mechanical device, focal spot to skin distance accuracy, image quality evaluation, and technical characteristic of cone-beam computed tomography) were selected for a total of 20 criteria.

• 비파괴검사학회지
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• 제26권2호
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• pp.69-76
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• 2006

차세대 원자로로 부각되고 있는 고온가스로에서는 윈자로에서는 고온 안정성 및 핵분열생성물 차단 성능이 우수한 TRISO(tri-isotropic) 핵연료를 사용하고 있다. TRISO 핵연료 입자는 직경이 약 1mm인 구 형태로 입자의 중심에는 직경 0.5mm의 핵연료 커널(kernel)이 포함되며 커널 외곽을 코팅 층이 에워싸고 있다. 이 코팅 층은 완충(buffer) PyC(pyrolytic carbon)층, 내부 PyC층, SiC층, 그리고 외부 PyC층으로 구성되어 있다. 각 코팅 층의 두께는 수십-백${\mu}m$ 범위이고 사양으로 정해져 있으며, 본 연구에서는 각 코팅 층의 두께를 비파괴적으로 측정하기 위하여 마이크로포커스 X-선 발생장치와 고해상도 X-선 평판(flat panel) 검출기초 구성된 정밀한 X-선 래디오그래피 장치를 개발하였다. 개발된 마이크로 X-선 래디오그래피 장치를 이용하여 $UO_2$ 핵물질 $ZrO_2$를 커널로 사용한 모의 TRISO 핵연료 입사에 대한 투과 영상을 획득한 후 디지털 영상처리 기술을 이용하여 코팅 층 사이의 경계선이 구분 가능하도록 영상을 개선하고 디지털 영상처리 알고리듬을 개발하여 코팅 층의 두께를 파동으로 측정하였다.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2016년도 제50회 동계 정기학술대회 초록집
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• pp.157.1-157.1
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• 2016

In this work, we experimentally investigated the solar absorption performance of Cu-based scalable nanostructured surfaces and compared their performance with the conventional TiNOX. We fabricated Cu-based nanostructured surfaces with a controlled chemical oxidation process applicable to a large area or complex geometry. We optimized the process parameters including the chemical compounds, dipping time and process temperature. We conducted both lab-scale and outdoor experiments to characterize the conversion efficiency of each absorber surfaces with single and double glazing setup. Lab-scale experiment was conducted with $50mm{\times}50mm$ absorber sample with 1-sun condition (1kW/m2) using a solar simulator (PEC-L01) with measuring the temperature at the absorber plate, cover glass, air gap and ambient. From the lab-scale experiment, we obtained ${\sim}91^{\circ}C$ and $94^{\circ}C$ for CuO and TiNOX surfaces after 1 hr of solar illumination at single glazing, respectively. To measure the absorber performance at actual operating condition, outdoor experiment was also conducted using $110mm{\times}110mm$ absorber sample. We measured the solar flux with thermopile detector (919P-040-50). From outdoor experiment, we observed ${\sim}123^{\circ}C$ and $131^{\circ}C$ for CuO and TiNOX with 0.6 kW/m2 insolation at double glazing, respectively. We showed that the suggested nanostructured CuO solar absorber has near-equivalent collection efficiency compared with the state-of-the-art TiNOX surfaces even with much simpler manufacturing process that does not require an expensive equipment.

• 한국방사선학회논문지
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• 제3권4호
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• pp.35-38
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• 2009

최근 의료영상분야에서 형광체와 광도전체 물질을 이용한 디지털 평판형 X선 영상검출기가 폭넓게 이용되고 있다. 본 연구는 CsI:Na 형광체층과 광민감도가 우수한 비정질 셀레늄(a-Se)층의 이중 접합구조로 구성된 변환구조 설계를 위한 몬테카를로 시뮬레이션과 X선에 대한 광학적 및 전기적 반응특성을 조사하였다. 먼저 CsI:Na의 발광스펙트럼과 a-Se의 광흡수 스펙트럼을 측정하여 X선에 의한 신호 변환특성을 분석하였다. 또한, 인가전기장의 함수에 따른 X선 민감도을 측정하여 상용화된 a-Se($500{\mu}m$)의 직접변환 검출기와 비교 평가하였다. 측정결과로부터, $10V/{\mu}m$에서 CsI:Na($180{\mu}m$)/a-Se($30{\mu}m$) 변환센서의 X선 민감도는 $7.31nC/mR-cm^2$ 이고, a-Se($500{\mu}m$) 검출기는 $3.95nC/mR-cm^2$로 약 2배 정도 높은 값을 보였다.

• Journal of Korean Neurosurgical Society
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• 제63권6호
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• pp.747-756
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• 2020

Objective : To evaluate the effectiveness and long-term outcome predictors of percutaneous sacroplasty (PSP). Methods : This single-center study assessed 40 patients with sacral insufficiency fractures using the short-axis technique under C-arm flat-panel detector computed tomography (CT). Two radiologists reviewed the patients' magnetic resonance and CT images to obtain imaging findings before PSP and determine technical success, respectively. The short-term outcomes were visual analog scale score changes and opioid usage reductions. Long-term outcomes were determined using telephone interviews and the North American Spine Society (NASS) patient-satisfaction index at least one year after PSP. Results : Technical success was achieved without any significant complications in 39 patients (97.5%). Telephone interviews were possible with 12 patients and failed in 10 patients; death was confirmed in 18 patients. Fifteen patients (50%) re-visited the hospital and received conservative treatment, including spinal injections. Nine patients reported positive satisfaction (NASS patient-satisfaction index 1 or 2), while the negative satisfaction group (NASS patient-satisfaction index 3 or 4, n=3) showed a higher incidence of compression fractures at the thoracolumbar spine level (66.7% vs. 22.2%) and previous spinal injection history (66.7% vs. 33.3%). The poor response group also showed higher incidences of facet joint arthrosis (100% vs. 55.6%), central canal stenosis (100% vs. 22.2%), neural foraminal stenosis (33.3% vs. 22.2%), scoliosis (100% vs. 33.3%), and sagittal malalignment (100% vs. 44.4%). Conclusion : PSP was effective for sacral insufficiency fractures and showed good long-term outcomes. Combined compression fractures in the thoracolumbar spine and degenerative lumbar pathologies could be possible poor outcome predictors.

• 대한방사선기술학회지:방사선기술과학
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• 제33권4호
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• pp.341-348
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• 2010

상 하지 촬영 시 서울 경기지역 병원의 FPD(Flat Pannel Detector) System 사용 실태와 격자 사용에 따른 환자 선량 및 C-D Phantom에 의한 화질평가, 임상 평가자들에 의한 영상평가를 한 결과 다음과 같은 결론을 얻었다. 1. FPD system(12대)의 사용 실태 조사결과 격자비는 8 : 1에서 13 : 1까지이며, 12 : 1이 6대로 가장 많았다. 이 중 격자의 탈 부착이 가능한 장비는 8대이지만, 사용하지 않는 것이 5대(62.5%)로 격자를 그대로 사용하는 곳이 9곳(75.5%)이었다. 2. 실험에 사용된 장비에서 격자사용으로 환자가 받은 선량이 4.13배에서 4.79배까지 많이 받는 것으로 나타났다. 3. 노출조건(mAs)의 변화(0.5배나 2.0배)에 따라 환자가 받는 선량의 차이는 환자 두께에 따라 크게 차이 나지는 않았다. 4. C-D Phantom에 따른 영상의 화질평가는 격자 사용 시와 노출량이 많아질 때 영상의 식별은 잘 되었다. 5. 임상 평가는 두께가 얇은 Hand PA 영상에서는 격자사용을 하지 않는 것이 더 좋았다. 두께가 두꺼운 Knee AP 영상에서는 격자를 사용하는 것이 좋다는 평가를 받았다. 그러나 환자선량이 적어진다면 격자를 사용하지 않겠다는 의견이 5명 중 3명으로 더 많았다.

• Macromolecular Research
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• 제10권1호
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• pp.2-12
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• 2002

The small-angle X-ray scattering (SAXS) beamline BL4C1 at the 2.5 GeV storage ring of the Pohang Accelerator Laboratory (PAL) has been in its first you of operation since August 2000. During this first stage it could meet the basic requirements of the rapidly growing domestic SAXS user community, which has been carrying out measurements mainly on various polymer systems. The X-ray source is a bending magnet which produces white radiation with a critical energy of 5.5 keV. A synthetic double multilayer monochromator selects quasi-monochromatic radiation with a bandwidth of ca. 1.5%. This relatively low degree of monochromatization is sufficient for most SAXS measurements and allows a considerably higher flux at the sample as compared to monochromators using single crystals. Higher harmonics from the monochromator are rejected by reflection from a flat mirror, and a slit system is installed for collimation. A charge-coupled device (CCD) system, two one-dimensional photodiode arrays (PDA) and imaging plates (IP) are available its detectors. The overall performance of the beamline optics and of the detector systems has been checked using various standard samples. While the CCD and PDA detectors are well-suited for diffraction measurements, they give unsatisfactory data from weakly scattering samples, due to their high intrinsic noise. By using the IP system smooth scattering curves could be obtained in a wide dynamic range. In the second stage, stating from August 2001, the beamline will be upgraded with additional slits, focusing optics and gas-filled proportional detectors.

• Journal of Korean Neurosurgical Society
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• 제65권6호
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• pp.801-815
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• 2022

Objective : To evaluate the stent apposition of a low-profile visualized intraluminal support (LVIS) device in distal internal carotid artery (ICA) aneurysms, examine its correlation with clinical and angiographic outcomes, and determine the predictive factors of ischemic adverse events (IAEs) related to stent-assisted coiling. Methods : We retrospectively analyzed a prospectively maintained database of 183 patients between January 2017 and February 2020. The carotid siphon from the cavernous ICA to the ICA terminus was divided into posterior, anterior, and superior bends. The anterior bends were categorized into angled (V) and non-angled (C, U, and S) types depending on the morphology and measured angles. Complete stent apposition (CSA) and incomplete stent apposition (ISA) were evaluated using unsubtracted angiography and flat-panel detector computed tomography. Dual antiplatelet therapy with aspirin 200 mg and clopidogrel 75 mg was administered. Clopidogrel resistance was defined as fewer responders (≥10%, <40%) and non-responders (<10%) based on the percent inhibition (%INH) of the VerifyNow system. These were counteracted by a dose escalation to 150 mg for fewer responders or substitution with cilostazol 200 mg for non-responders. IAEs included intraoperative in-stent thrombosis, transient ischemic attack, cerebral infarction, and delayed in-stent stenosis. A multivariate logistic regression analysis was used to determine the predictive factors for ISA and IAEs. Results : There were 33 ISAs (18.0%) and 27 IAEs (14.8%). The anterior bend angle was narrower in ISA (-4.16°±25.18°) than in CSA (23.52°±23.13°) (p<0.001). The V- and S-types were independently correlated with the ISA (p<0.001). However, treatment outcomes, including IAEs (15.3% vs. 12.1%), aneurysmal complete occlusion (91.3% vs. 88.6%), and recanalization (none of them), did not differ between CSA and ISA (p>0.05). The %INH of 27 IAEs (13.78%±14.78%) was significantly lower than that of 156 non-IAEs (26.82%±20.23%) (p<0.001). Non-responders to clopidogrel were the only significant predictive factor for IAEs (p=0.001). Conclusion : The angled and tortuous anatomical peculiarity of the carotid siphon caused ISA of the LVIS device; however, it did not affect clinical and angiographic outcomes, while the non-responders to clopidogrel affected the IAEs related to stent-assisted coiling.

• Restorative Dentistry and Endodontics
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• 제34권1호
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• pp.51-60
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• 2009

본 연구는 현재 시판 되고 있는 여러 개의 상아질 접착제를 임상 술식에서와 같은 방법으로 사용한 다음 열순환 후 접착계면의 변화를 관찰 비교하고자 했다. 발거 한지 한 달 이내인 대구치 28개의 교합면 상아질 표면에 4종의 상아질 접착제 (OptiBond FL [OP], AdheSE [AD], Clearfil SE Bond [CL], Xeno III [XE]) 중 하나를 적용한 뒤 복합 레진 (Premisa, Kerr) 을 1 mm 두께로 올린 후 광중합 하였다. $4^{\circ}C$ 증류수에서 6일간 보관한 뒤, 치아의 정중선으로부터 수직으로 절단 하여 그 중 절반의 치아에서 2 mm 두께의 시편을 얻은 다음 남은 반쪽의 치아는 10,000회의 열순환을 가한 뒤 ($5^{\circ}-55^{\circ}$, 침지 시간 25초, 대기 시간 5초) 같은 방법으로 2 mm 두께의 시편을 얻었다. 연마한 시편을 24시간 동안 50% ammoniacal silver nitrate solution에 담근 다음 photo-developing solution에서 8시간 동안 환원시켰다. 계면을 가로지르는 5개의 line상에서 wavelength dispersive spectrometry (WDS) detector를 이용하여 주사전상에 있는 원소들의 중량비를 계산하였다. 또한 열순환 전과 후의 시편에서 얻어진 5개의 silver 측정치를 서로 비교하였다. 열순환 전의 접착제층(adhesive layer)에서는 OP에서 가장 적은 silver의 투과가 관찰되었으며 (p < 0.0001), CL, AD, XE 순으로 투과 량이 증가함을 보였다. 혼성층 (Hybrid layer) 에서는 CL의 투과량이 가장 적었다 (p = 0.0039). 열순환 후에 접착제층과 혼성층에서 silver의 투과량은 증가하지는 않았다. Scanning electron microscopy (SEM) 사진을 통하여 각 시편의 접착 계면에서 접착제에 따른 특이적인 silver의 투과상을 관찰할 수 있었다. 전반적으로 OP 와 CL의 접착계면이 열순환 과정 중에도 온전히 유지됨을 볼 수 있었다. 접착 계면에서의 수분 투과 양상은 각 접착제에 따라 다른 형태를 보였으며 열 순환에 의해 유의할 만한 변화를 야기하지는 않았다.