• 대한전자공학회논문지
• /
• 제25권4호
• /
• pp.422-429
• /
• 1988

The photoconductive multilayer of Se-As(hole blocking layer)/Se-As-Te (photoconductive layer) /Se-As (layer for supporiting hole transport)/Se-As(layer or controlling total capacitance)/Sb2S3(electron blocking layer) was fabricated and its electrical and optical properties were investigated. The photoconductive multilayer is made of evaporated a-Se as the base material, doped with As and Te to prevent the crystallization of a-Se and to enhance red sensitivity, respectively. The multilayer with good image reproducibility has the following deposition condition. The first layer has the thickness of 250\ulcornerat the deposition rate of 250\ulcornersec. The second layer has the thickness of 800\ulcornerat the deposition rate of 250\ulcornersec. The third layer has the thickness of 125\ulcornerat the deposition rate of 250\ulcornersec. The fourth layer has the thickness of 1700\ulcornerunder the Ar gas ambient of 50x10**-3torr. The image pick-up tube, employing this multilayer demonstrates the following characteristics. The photosensitivity is 0.8, the resolution limit is above 300TV line, and the decay lag is about 7%. And spectral response convers the whole visible range. Therfore the application to color TV camera is expected.

• 한국환경보건학회:학술대회논문집
• /
• 한국환경보건학회 2003년도 Challenges and Achievements in Environmental Health
• /
• pp.76-85
• /
• 2003

Mass and elemental dry deposition fluxes and ambient particle size distributions were measured using dry deposition plates and a cascade impactor, from March to November 1998 in Seoul, Korea. During the spring sampling period several yellow sand events characterized by long range transport from China and Mongolia impacted the area. During these events the mass fluxes were statistically the same as during springtime non-yellow-sand events. However, most elemental fluxes were higher. In general, the flux ratios of both crustal (Al, Ca, Mn) and anthropogenic elements (Ni, Pb) to total mass measured during the daytime yellow-sand events were substantially higher than those measured in spring daytime during non-yellow-sand time periods. During all seasons the average measured daytime fluxes were about two times higher than at nighttime. The flux of primarily anthropogenic metals (Cu, Ni, Pb, Zn) and Mn was on average one to two orders of magnitude lower than the flux of the crustal metals Al and Ca. As is typically found two modes, fine (0.1∼l.0 $\mu\textrm{m}$) and coarse (1.0∼10.0 $\mu\textrm{m}$) were present in the measured size distributions (<10 $\mu\textrm{m}$). The particles in the coarse mode constitute a major portion of the measured mass size distribution during the yellow-sand events possibly due to the long-range transport of those particles from China.

• 대한기계학회논문집A
• /
• 제24권8호
• /
• pp.1958-1967
• /
• 2000

Rapid Prototyping( RP ) has been increasingly applied in the process of design and development of new products. RP can shrink the time and expense required to bring a new product from initial concept to production. However, the necessity of using RP for short-run manufacturing is continuously driving a development of a cost-effective technique that will produce completely-finished quality parts in a very short time. To meet these demands, the improvements in production speed, accuracy materials, and cost are crucial. Thus, a new hybrid-RP system performing both deposition and machining in a station is proposed in this paper. It incorporates both material deposition in layers and material removal from the outer surface of the layer to produce the required surface finish. The new hybrid-RP system can dramatically reduce the total build time and fabricate largo-sized and freeform objects because it uses very thick layers, i.e.

• 암석학회지
• /
• 제22권4호
• /
• pp.273-289
• /
• 2013

강하화산재는 농업과 기반시설에 다양한 형태의 피해를 발생시킬 수 있는 악명 높은 재해이며, 특별히 항공과 인체 건강에 가장 유해하다. 본 연구는 백두산 화산으로부터 폭발적 분화에 의하여 화산재가 확산되고 퇴적되는 것을 모델링하기 위한 목적으로 개념적인 모델 설계를 논의하고자 한다. 이는 모델의 가정과 경계 조건에 대한 토의와 더불어 개념적인 모델의 상세 다이어그램, 가능한 입력 파라미터, 단위, 방정식에 대한 논의를 포함한다. 모델에 포함되어 있는 두 가지 주요 과정은 화산재의 확산과 퇴적이며, 만약 모델이 설계되면 모델을 실행시켜 얻을 수 있는 것은 분연주에 포함된 미세 화산재의 총량, 화산재의 이동 거리, 지표면에 침적되는 화산재 두께 등이다.

• 한국대기환경학회지
• /
• 제11권4호
• /
• pp.351-359
• /
• 1995

In order to investigate geochemical behaviors of artificial radionuclide($^{137}$ Cs), the fallout deposition of arificial radioisotope($^{137}$ Cs) was measured from May to October in 1994 at the Korea Ocean Research & Development Institute(KORDI), Ansan, Kyunggido, Korea. And to study radioisotopic behavior and cumulative action in soil, soil samples were collected from Kwang-Leung Forest, Kyunggidom and artificial radioisotope ($^{137}$ Cs) and natural radioisotope($^{210}$ Pb) were identified. The amount of $^{137}$ Cs in atmosphere collected by wet deposition process in May was found to be 4.95 to 11.96mBq m$^{-2}$ whereas the amounts of $^{137}$ Cs by dry deposition process in May and October were found to be 4.0mBq g$^{-1}$ and 3.0mBq g$^{-1}$ , respectively. The amount of $^{137}$ Cs accumulated in soil was measured to be 311mBq cm$^{-2}$ , which contained 83% of the total inputs from atmospheric fallout (374 mBq cm$^{-2}$ ) since 1960s. In addition, the accumulation rate and the annual flux of $^{210}$ Pb into soils were 0.32cm yr$^{-1}$ and 34 mBq cm$^{-2}$ yr$^{-1}$ , respectively. Conclusively, it was found that arificial radioisotopes were mainly from the stratosphere and soil resupension of continental China through the troposphere.

• 한국재료학회지
• /
• 제12권5호
• /
• pp.363-368
• /
• 2002

we proposed the use of $Si_2H_ 6/H_2$ chemistry for selective silicon epitaxy growth by low-pressure chemical vapor deposition(LPCVD) in the temperature range $600~710^{\circ}C$ under an ultraclean environment. As a result of ultraclean processing, an incubation period of Si deposition only on $SiO_2$ was found, and low temperature epitaxy selective deposition on Si was achieved without addition of HCI. Total gas flow rate and deposition pressure were 16.6sccm and 3.5mtorr, respectively. In this condition, we selectively obtained high-quality epitaxial Si layers of the 350~1050$\AA$ thickness. In older to extend the selectivity, we kept high pressure $H_2$ environment without $Si_2H_6$ gas for few minutes after first incubation period and then we conformed the existence of second incubation period.

• 방사성폐기물학회지
• /
• 제21권1호
• /
• pp.165-173
• /
• 2023

Various linear system solvers with multi-physics analysis schemes are compared focusing on the near-field region considering thermal-hydraulic-chemical (THC) coupled multi-physics phenomena. APro, developed at KAERI for total system performance assessment (TSPA), performs a finite element analysis with COMSOL, for which the various combinations of linear system solvers and multi-physics analysis schemes should to be compared. The KBS-3 type disposal system proposed by Sweden is set as the target system and the near-field region, which accounts for most of the computational burden is considered. For comparison of numerical analysis methods, the computing time and memory requirement are the main concerns and thus the simulation time is set up to one year. With a single deposition hole problem, PARDISO and GMRES-SSOR are selected as representative direct and iterative solvers respectively. The performance of representative linear system solvers is then examined through a problem with an increasing number of deposition holes and the GMRES-SSOR solver with a segregated scheme shows the best performance with respect to the computing time and memory requirement. The results of the comparative analysis are expected to provide a good guideline to choose better numerical analysis methods for TSPA.

• 한국수자원학회논문집
• /
• 제37권11호
• /
• pp.959-967
• /
• 2004

충북 청주시에 위치한 충북대학교에서 강수에 따른 습성강하물 중의 TN, TP 및 COD의 농도와 오염부하를 조사하였다 강수사상에 대한 샘플은 1998년에서 2003년까지 채집되었다. 오염물질의 강수량가중평균 농도는 TN이 0.60mg/L, TP가 0.014mg/L, COD는 4.8mg/L이었는데, 이는 각각의 산술평균보다 26, 18, 14% 작게 나타났다. TN, TP 및 COD의 농도는 강수량이 증가함에 따라 감소하는 경향을 나타냈다. 모든 수질항목은 됨에 가장 많이 나타났는데, 이는 풍식 및 황사에 의한 먼지, 꽃가루 등 때문으로 생각된다. 습성강하물의 평균 연간부하는 TN 7.9kg/ha$\cdot$yr, TP 0.19kg/ha$\cdot$yr, COD 53.9ka/ha$\cdot$yr로 나타났는데, 이를 일본에서 보고된 각각의 연간부하와 비교하면 TN과 TP는 비슷했으나, COD는 약간 놀게 나타났다.

• Journal of Radiation Protection and Research
• /
• 제23권4호
• /
• pp.243-249
• /
• 1998

원자력 사고 후 우유에 대한 비상대응방법론을 비용/편익 분석법에 근거하여 고안하였다. 목초의 왕성한 성장시기인 8월 15일을 방사성물질의 침적시점(사고시점)으로 가정하여 지표위 방사성물질의 농도, 침적 후 대응행위의 시작시점과 수행기간의 함수로써 적용결과를 논의하였다. 침적 후 우유내 방사성물질의 농도는 동적섭식경로모델 DYNACON으로부터 예측되었다 대응행위로는 침적 후 첫해에 피폭을 효과적으로 줄일 수 있고 수행하기 용이한 섭취금지와 비오염 사료대체가 고려되었다. 대응행위 수행에 따른 총비용은 피폭부담과 금전비용의 합으로 평가하였다. 침적 후 신속한 대응은 소요되는 금전비용에 대한 피폭저감 측면에서 중요한 변수였다. 많은 경우 비오염 사료대체는 섭취금지보다 비용측면에서 효과적인 대응행위였다. 대응행위를 빨리 취할수록 대응행위의 정당화 및 최적기간은 증가하였다.

• 한국측량학회지
• /
• 제34권2호
• /
• pp.153-159
• /
• 2016

Rivers refer to either natural or artificial structures whose primary functions are flood control and water conservation. Due to recent localized torrential downpours led by climate change, large amounts of eroded soil have been carried away, forming deposits downstream, which in turn degrades the capacity to fulfill these functions. To manage rivers more effectively, we need data on riverbed erosion and deposition. However, environmental factors make it challenging to take measurements in rivers, and data errors tend to prevent researchers from grasping the current state of erosions and deposits. In this context, the aim of the present study is to provide basic data required for river management. To this end, the author made annual measurements with a Real-time Kinematic-Global Positioning System (RTK-GPS) and a total station in Pats Cabin Canyon, Oregon, United States, and also prepared thematic maps of erosion and deposition thickness as well as water depth profiles based on a GIS spatial analysis. Furthermore, the author statistically analyzed the accuracy of three dimensional (3D) measurement points and only used the data that falls within two standard deviations (i.e. ±2σ). In addition, the author determined a threshold for a DEM of Difference (DoD) by installing measurement points in the rivers and taking measurements, and then estimated erosion and deposition thickness within a confidence interval of ±0.1m. Based on the results, the author established reliable data on river depth profiles and thematic maps of erosion and deposition thickness using pre-determined work flows. It is anticipated that the riverbed data can be utilized for effective river management.