• 핵의학기술
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• 제13권1호
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• pp.63-66
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• 2009

Purpose: ACR (American College of Radiology) offers variable parameters to PET/CT quality control by using ACR Phantom. ACR Phantom was made to evaluate parameters which are uniformity, attenuation, scatter, contrast and resolution. Manual analysis method wasn't good for the use of QC because values of parameter were changed as it may user and it takes long time to analysis. Ki-Chun Lim, a nuclear scientist in AMC, developed program that automatically analysis values of parameter by using ACR Phantom to overcome above problems. In this study, we evaluated automatic analysis program's usability, through the comparing SUV of each method, reproducibility of SUV when repeated analysis and the time required. Materials and Methods: Using Flangeless Esser PET Phantom, the ideal ratio of 4 : 1 hot cylinder and BKG but it actually showed a ratio of 3.89 to 1 hot cylinder and BKG. SIEMENS Biograph True Point 40 was used in this study. We obtained images using ACR phantom at Fusion WB PET Scan condition (2 min/bed) and 120 kV, 100 mAs CT condition. Using True X method, 3 iterations, 14 subsets, Gaussian filter, FWHM 4 mm and Zoom Factor 1.0, $168{\times}168$ image size. We obtained Max. & Min. SUV and SUV Mean values at Cylinder (8, 12, 16, 25 mm, Air, Bone, Water, BKG) by automatic program and obtained SUV by manual method. After that, we compared manual and automatic method. we estimate the time required from opened the image data to final work sheet was completed. Results: Automatic program always showed same result and same the time required. At 8, 12, 16 and 25 m cylinder, manual method showed 6.69, 3.46, 2.59, 1.24 CV values. The larger cylinder size became, the smaller CV became. In manual method, bone, air, water's CV were over 9.9 except BKG (2.32). Obtained CV of Mean SUV showed BKG was low (0.85) and bone was high (7.52). The time required was 45 second, 882 second respectably. Conclusions: As a result of difference automatic method and manual method, automatic method showed always same result, manual method showed that the smaller hot cylinders became, the lager CV became. Hot cylinders mean region size, the smaller hot cylinder size becomes we had some trouble in doing ROI poison setting. And it means increase in variation of SUV. The Study showed the time required of automatic method was shorten then manual method.

• 한국진공학회:학술대회논문집
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• 한국진공학회 1999년도 제17회 학술발표회 논문개요집
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• pp.62-62
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• 1999

Carbon based materials have many attractive properties such as a wide band gap, a low electron affinity, and a high chemical and mechanical stability. Therefore, researches on the carbon-based materials as field emitters have been drawn extensively to enhance the field emission properties. Especially, diamond gives high current density, high current stability high thermal conductivity durable for high temperature operation, and low field emission behaviors, Among these properties understanding the origin of low field emission is a key factor for the application of diamond to a filed emitter and the verification of the emission site and its distribution of diamond is helpful to clarify the origin of low field emission from diamond There have been many investigations on the origin of low field emission behavior of diamond crystal or chemical vapor deposition (CVD) diamond films that is intentionally doped or not. However, the origin of the low field emission behavior and the consequent field emission mechanism is still not converged and those may be different between diamond crystal and CVD diamond films as well as the diamond that is doped or not. In addition, there have been no systematic studies on the dependence of nondiamond carbon on the spatial distribution of emission sites and its uniformity. Thus, clarifying a possible mechanism for the low field emission covering the diamond with various properties might be indeed a difficult work. On the other hand, it is believed that electron emission mechanisms of diamond are closely related to the emission sites and its distributions. In this context, it will be helpful to compare the spatial distribution of emission sites and field emission properties of the diamond films prepared by systematic variations of structural property. In this study, we have focused on an understanding of the field emission variations of structural property. In this study, we have focused on an understanding of the field emission mechanism for the CVD grown undoped polycrystalline diamond films with significantly different structural properties. The structural properties of the films were systematically modified by varying the CH4/H2 ratio and/or applying positive substrate bias examined. It was confirmed from the present study that the field emission characteristics are strongly dependent on the nondiamond carbon contents of the undoped polycrystalline diamond films, and a possible field emission mechanism for the undoped polycrystalline diamond films is suggested.

• 자원환경지질
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• 제26권1호
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• pp.67-81
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• 1993

This dissertation is a basic research on the degradation of rocks and aims at clarifying the relations between the progression of degree of weathering and the variation of chemical composition. The author wants to make clear the degradation of rocks and the process of formation of sedimentary rocks from a standpoint of elucidation of migration of elements. This study is considered to be significant not only as a part of research on the distribution of earth crust materials but as the petrogenesis of rocks. The chemical studies on the weathered rocks have been started relatively early and there are not a few researches on them: Goldich, 1938; Harris, et al., 1966; Ruxton, 1968; Berner, et al., 1982; Kanuss, 1983; Lasaga, 1984; Siagel, 1984. The degree of migration of elements in weathering is the composite result of various factors. Because, at the present time, it is difficult to clarify the individual and composite effects of each factor theoretically and quanititatively, we must accumulate empirical data and use them relatively. In such consideration the author acquired some data of chemical weathering from the chemical analysis of granitic and basaltic rocks in and around Fukuoka city, Japan and granitic rocks in and around Chonju and Iri cities, Korea. Because both rock types studied can be considered as representative materials of acidic and basic rocks compsing the earth crust, it is significant to examine the phenomena of weathering of both rock types. The following results are obtained from the analysis and examinations of chemical compositions of the original and weathered rocks. The loss rate of major elements has no uniformity, but the following relation holds in general; Ca, Na> K, Si> Mg> Fe, Al. As weathering proceeds, the ratio of $Al_2O_3/CaO$ shows increasing phenomena, and that of $Na_2O/CaO$ decreasing. The range of migration of composition is broad in basaltic rocks but narrow in granitic rocks. The reason is that the chemical weathering of basaltic rocks progresses more easily than that of granitic rocks. The chemical weathering potenitial index of basaltic rocks in larger than that of granitic rocks. The reason is that the chemical weathering of basaltic rocks proceeds more easily than that of granitic rocks. In weathering, the decrease of mobile cations such as $Ca^{2+}$, $Na^{2+}$, $Mg^{2+}$ and the increase of $H_2O$ in basaltic rocks are more obvious than in granitic rocks.

• Ecology and Resilient Infrastructure
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• 제6권4호
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• pp.179-190
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• 2019

금강의 용담댐 하류부터 대청댐 상류 구간을 대상으로 멸종위기 1급으로 지정된 감돌고기의 서식 실태를 파악하고자 어류조사를 실시하였다. 출현된 어류의 개체수를 기준으로 생물다양도 분석을 실시하였고, 채집된 감돌고기를 이용하여 생물학적 건강성 및 물리적 서식환경을 정량적으로 분석하였다. 조사결과에 따르면 감돌고기의 서식범위는 용담댐 하류부터 대청댐 상류 가덕교 700 m 하류 지점까지 서식이 확인되었다. 전체 출현종의 생물다양도 분석결과는 전체적으로 우점도 지수가 낮았고, 상대적으로 종 다양도 및 균등도 지수가 높아 어류군집이 안정된 것으로 평가되었다. 또한 본 연구에서 채집된 감돌고기는 전장-무게 상대성정식 및 비대지수 (CF) 분석결과 정상적인 성장 및 영양 상태로 확인되었다. 감돌고기의 물리적 서식환경은 수심 0.3 - 0.6 m, 유속 0.3 - 0.7 m/s, 하상재료는 호박돌 - 전석의 범위에서 높은 출현빈도로 나타났다. 이와 같은 결과는 금강에서 감돌고기의 공간적인 서식범위와 선호하는 물리적 서식환경에 대한 기초자료로서 향후 서식지 복원 및 관리를 위한 자료로 활용될 수 있을 것으로 판단된다.

• 한국철도학회논문집
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• 제19권2호
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• pp.204-212
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• 2016

국내 궤도 흙노반재료의 선정기준은 기초물성 값(입경, 200번체 통과량($P_{200}$), 4번체 통과량($P_4$), 균등계수($C_u$), 곡률계수($C_c$)등)을 이용하는 통일분류법에 의존하고 있으며, 선정된 궤도노반의 현장 다짐도는 들밀도 시험 및 반복평판재하시험 결과 $E_{v2}$에 의해 파악한다. 그러나 궤도노반의 변형 및 안정성에 미치는 가장 큰 영향요소는 강성(Stiffness)이므로, 노반재료의 분류특성은 기초물성 값 자체 보다는 다짐 후 변형계수를 활용하는 것이 보다 정확하다고 할 수 있다. 본 연구에서는 궤도노반에 사용되는 국내 대표적인 흙 재료의 기초물성과 현장시험에 의한 변형계수($E_{v2}$, $E_{vd}$)와의 상관식을 도출하였다. 이와 같은 상관특성은 성능설계를 위한 국내 고유의 철도궤도용 전용흙분류기준수립을 위한 근거로 사용될 수 있다.

• 생명과학회지
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• 제28권11호
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• pp.1262-1267
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• 2018

국지적 환경에서 패치 분포 형태는 일차적으로 식물의 공간적 양상으로 나타나고, 임의화 과정은 패치를 결정하는 공간적 가설을 입증하는데 이용된다. 주름조개풀(Oplismenus undulatifolius (Ard.) P. Beauv. var. undulatifolius)은 Poaceae과 Oplismenus 속에 속하는 초본류이다. 이 종은 온대, 아열대, 열대에 분포한다. 이 지역의 주름조개풀이 일정한 분포인지 응집하는 분포인지 여러 패치 지표를 사용하여 분석하였다. 한우산의 집단 밀도는 0.453에서 4.375였으며 평균은 2.387이였다. 소형과 중형 프롯($2m{\times}2m$, $2m{\times}4m$, $4m{\times}4m$, $4m{\times}8m$, and $8m{\times}8m$)에서 주름조개풀은 응집형태를 보였다. 반면에 대형 플롯($8m{\times}16m$, $16m{\times}16m$, and $16m{\times}32m$)에서는 일정한 분포 양상을 나타내었다. 평균 응집 계수(M*)와 패치 지표(PAI)는 양의 값을 보였다. 응집은 여러 환경적 요인에 기인하는데 등산객들에 의해 방해되고 있었다. 따라서 주름조개풀은 이 지역에서 본래의 기본 생태적 지위를 누리지 못하고 있음을 보여주었다.

• 한국건설관리학회논문집
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• 제23권1호
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• pp.98-105
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• 2022

밀폐된 공간에서 인공적인 방법으로 작물을 재배하는 수직형 스마트 팜은 공기 환경 설비를 적절히 활용하여 적정한 생육환경을 조성하는 것이 중요하다. 하지만 국내 수직형 스마트 팜 기업들은 체계적인 방법이 아닌 경험적 데이터에 의존하여 생육환경을 조성하고 있다. IoT를 활용하여 체계적이고 정밀한 모니터링을 토대로 생육환경을 조성한다면 작물의 생산 수율을 높이고 수익성을 극대화할 수 있다. 본 연구의 목적은 IoT를 활용하여 모니터링 시스템을 구성하고, 작물 재배에 주요한 요인인 온도 환경의 불균형을 실증하여 그 원인을 분석하는 데 있다. LED와 냉방기의 가동 방식을 달리하며 1) 다층 선반의 수평 온도 분포를 측정한 결과 센서 간에 "최대 1.7℃"의 온도 격차를 보였다. 2) 수직 온도 분포를 측정한 결과 "최대 6.3℃"의 온도 차이를 보였다. 이러한 온도 격차를 줄이기 위해서는 공조설비의 적절한 배치와 운영 방식에 대한 전략이 필요하다.

• Nuclear Engineering and Technology
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• 제54권2호
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• pp.479-485
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• 2022

At the Korea Institute of Radiological and Medical Sciences, physical human phantoms were developed to evaluate various radiation protection quantities, based on the mesh-type reference computational phantoms of the International Commission on Radiological Protection. The physical human phantoms were fabricated such that a radiophotoluminescent glass dosimeter (RPLGD) with a Tin filter, namely GD-352M, could be inserted into them. A Tin filter is used to eliminate the overestimated signals in low-energy photons below 100 keV. The measurement uncertainty of the RPLGD reader system based on GD-352M should be analyzed for obtaining reliable protection quantities before using it for practical applications. Generally, the measurement uncertainty of RPLGD systems without Tin filters is analyzed for quality assurance of radiotherapy units using a high-energy photon beam. However, in this study, the measurement uncertainty of GD-352M was analyzed for evaluating the protection quantities. The measurement uncertainty factors in the RPLGD include the reference irradiation, regression curve, reproducibility, uniformity, energy dependence, and angular dependence, as described by the International Organization for Standardization (ISO). These factors were calculated using the Guide to the Expression of Uncertainty in Measurement method, applying ISO/ASTM standards 51261(2013), 51707(2015), and SS-ISO 22127(2019). The measurement uncertainties of the RPLGD reader system with a coverage factor of k = 2 were calculated to be 9.26% from 0.005 to 1 Gy and 8.16% from 1 to 10 Gy. A blind test was conducted to validate the RPLGD reader system, which demonstrated that the readout doses included blind doses of 0.1, 1, 2, and 5 Gy. Overall, the E_n values were considered satisfactory.

• 문화기술의 융합
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• 제8권5호
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• pp.515-524
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• 2022

도시철도 침목플로팅궤도(STEDEF)의 분기기는 콘크리트 도상에 매입된 목침목과 침목 하부의 침목방진패드로 구성된 방진궤도로서 침목방진패드의 열화 및 이에 따른 스프링강성의 변화가 침목지지조건의 변화를 초래할 수 있다. 현재 약 21년의 공용기간 동안 발생된 망간크로싱의 손상수량은 전체 부설수량 대비 약 17%로 조사되었으며, 사용 기간 15년 이후(누적통과톤수 약 5.5억톤)부터 손상 물량이 증가하는 것으로 분석되었다. 본 연구에서는 실물 망간크로싱과 차륜의 형상을 모사한 3차원 수치모델을 이용한 매개변수 해석(차륜의 위치, 침목지지조건 및 동적 윤중의 크기)을 수행하여 실제 현장에서 발생된 망간크로싱의 손상유형 및 발생원인을 분석하였다. 연구결과, 노즈부 주변 침목에 뜬침목이 발생된 경우, 설계 궤도충격계수가 적용된 동적윤중 작용 시 노즈부 단면의 발생응력이 항복강도를 초과하였으며, 이는 실제 현장에서 발생된 손상위치와 비교적 잘 일치하는 것으로 분석되었다. 따라서 망간크로싱의 손상을 최소화하기 위해서는 노즈부 주변의 침목지지조건을 일정한 수준으로 유지하고, 손상된 망간크로싱 교체 시에는 침목 하부 경계조건의 균일성 확보를 위해 침목방진패드를 함께 교체하는 것이 바람직할 것으로 분석되었다.

• 한국분말재료학회지
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• 제30권4호
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• pp.324-331
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• 2023

Lithium (Li) is a key resource driving the rapid growth of the electric vehicle industry globally, with demand and prices continually on the rise. To address the limited reserves of major lithium sources such as rock and brine, research is underway on seawater Li extraction using electrodialysis and Li-ion selective membranes. Lithium lanthanum titanate (LLTO), an oxide solid electrolyte for all-solid-state batteries, is a promising Li-ion selective membrane. An important factor in enhancing its performance is employing the powder synthesis process. In this study, the LLTO powder is prepared using two synthesis methods: sol-gel reaction (SGR) and solid-state reaction (SSR). Additionally, the powder size and uniformity are compared, which are indices related to membrane performance. X-ray diffraction and scanning electron microscopy are employed for determining characterization, with crystallite size analysis through the full width at half maximum parameter for the powders prepared using the two synthetic methods. The findings reveal that the powder SGR-synthesized powder exhibits smaller and more uniform characteristics (0.68 times smaller crystal size) than its SSR counterpart. This discovery lays the groundwork for optimizing the powder manufacturing process of LLTO membranes, making them more suitable for various applications, including manufacturing high-performance membranes or mass production of membranes.