압축 벤토나이트 완충재의 비열 추정

윤석,김건영,백민훈 한국방사성폐기물학회 2017 방사성폐기물학회지 Vol.15 No.3

고준위폐기물을 처분하기 위한 심층 처분시설은 지하 500~1,000 m 깊이의 암반층에 설치된다. 심층 처분시스템의 구성 요 소로는 처분용기, 완충재, 뒷채움 및 근계 암반이 있다. 이 중 완충재는 심층 처분시스템에 있어 필수적인 요소인데, 완충재 는 지하수 유입으로부터 처분용기를 보호하고, 방사성 핵종 유출을 저지한다. 처분용기에서 발생하는 고온의 열량은 완충 재로 전파되기에 완충재의 열물성은 처분시스템의 안정성 평가에 상당히 중요하다고 할 수 있다. 완충재의 열전도도 규명 에 대한 연구는 많이 진행되고 있는 반면, 비열에 대한 연구는 미진한 상태이다. 따라서 본 연구에서는 국내 경주산 압축 벤 토나이트 완충재(KJ-II)에 대한 비열 추정 모델을 개발하고자 하였다. 압축 벤토나이트 완충재의 비열은 이중 탐침법을 이용 하여 다양한 포화도와 건조밀도에 따라 측정하였으며, 총 33개의 실험 데이터를 토대로 회귀분석을 이용하여 경주 압축 벤 토나이트의 비열을 추정할 수 있는 모델을 제시하였다. A geological repository for the disposal of high-level radioactive waste is generally constructed in host rock at depths of 500~1,000 meters below the ground surface. A geological repository system consists of a disposal canister with packed spent fuel, buffer material, backfill material, and intact rock. The buffer is indispensable to assure the disposal safety of high-level radioactive waste, and it can restrain the release of radionuclides and protect the canister from the inflow of groundwater. Since high temperature in a disposal canister is released to the surrounding buffer material, the thermal properties of the buffer material are very important in determining the entire disposal safety. Even though there have been many studies on thermal conductivity, there have been only few studies that have investigates the specific heat capacity of the bentonite buffer. Therefore, this paper presents a specific heat capacity prediction model for compacted Gyeongju bentonite buffer material, which is a Ca-bentonite produced in Korea. Specific heat capacity of the compacted bentonite buffer was measured using a dual probe method according to various degrees of saturation and dry density. A regression model to predict the specific heat capacity of the compacted bentonite buffer was suggested and fitted using 33 sets of data obtained by the dual probe method.

A Prediction of Specific Heat Capacity for Compacted Bentonite Buffer

Seok Yoon,Geon-Young Kim,Min-Hoon Baik 한국방사성폐기물학회 2017 방사성폐기물학회지 Vol.15 No.3

고준위폐기물을 처분하기 위한 심층 처분시설은 지하 500~1,000 m 깊이의 암반층에 설치된다. 심층 처분시스템의 구성 요 소로는 처분용기, 완충재, 뒷채움 및 근계 암반이 있다. 이 중 완충재는 심층 처분시스템에 있어 필수적인 요소인데, 완충재 는 지하수 유입으로부터 처분용기를 보호하고, 방사성 핵종 유출을 저지한다. 처분용기에서 발생하는 고온의 열량은 완충 재로 전파되기에 완충재의 열물성은 처분시스템의 안정성 평가에 상당히 중요하다고 할 수 있다. 완충재의 열전도도 규명 에 대한 연구는 많이 진행되고 있는 반면, 비열에 대한 연구는 미진한 상태이다. 따라서 본 연구에서는 국내 경주산 압축 벤 토나이트 완충재(KJ-II)에 대한 비열 추정 모델을 개발하고자 하였다. 압축 벤토나이트 완충재의 비열은 이중 탐침법을 이용 하여 다양한 포화도와 건조밀도에 따라 측정하였으며, 총 33개의 실험 데이터를 토대로 회귀분석을 이용하여 경주 압축 벤 토나이트의 비열을 추정할 수 있는 모델을 제시하였다. A geological repository for the disposal of high-level radioactive waste is generally constructed in host rock at depths of 500~1,000 meters below the ground surface. A geological repository system consists of a disposal canister with packed spent fuel, buffer material, backfill material, and intact rock. The buffer is indispensable to assure the disposal safety of high-level radioactive waste, and it can restrain the release of radionuclides and protect the canister from the inflow of groundwater. Since high temperature in a disposal canister is released to the surrounding buffer material, the thermal properties of the buffer material are very important in determining the entire disposal safety. Even though there have been many studies on thermal conductivity, there have been only few studies that have investigates the specific heat capacity of the bentonite buffer. Therefore, this paper presents a specific heat capacity prediction model for compacted Gyeongju bentonite buffer material, which is a Ca-bentonite produced in Korea. Specific heat capacity of the compacted bentonite buffer was measured using a dual probe method according to various degrees of saturation and dry density. A regression model to predict the specific heat capacity of the compacted bentonite buffer was suggested and fitted using 33 sets of data obtained by the dual probe method.

Dual-structure of Expansive Clays and its Response to Hydro-mechanical Loadings: A Review

Jae Owan Lee,Yohan Cha,Changsoo Lee,Jin-Seop Kim 한국방사성폐기물학회 2022 한국방사성폐기물학회 학술논문요약집 Vol.20 No.1

Expansive clays (for examples, bentonites) are favored as buffer and backfill materials because of their low hydraulic conductivity, high swelling potential, and good mechanical properties, and are installed in highly compacted blocks in repositories. Compacted expansive clays have a dual-structure system: macrostructural system which is a complex of clay aggregates with the inter-aggregate pores (macropores) which can be filled by either liquids or gases; microstructural system with the intraaggregate pores between or within clay particles (micropores) which is usually considered to be saturated by liquid. Understanding the dual-strucure system of expansive clays is essential for characterizing and modeling multiphysics (stress-strain, swelling pressure, etc.) in buffers and backfills. Existing multiphysics studies of expansive clays, as in non-expansive soils, were mostly conducted with a single structure approach based on the behavior of macropores, and there have been limitations in the comprehensive interpretation and modeling of experimental results. However, with the recent development of measurement techniques, a lot of available information on the pore structure of compacted expansive clays has been reported, and with the results, a dual-structure approach considering both microstructural and macrostructural systems has been increasingly applied to improve the modeling of multiphysics of expansive clays. This study reviewed the dual-structure system of compacted expansive clays, analyzed previous studies on its evolution according to hydromechanical loading (loading-unloading and wetting-drying paths), and based on these, intended to provide technical knowledge and information needed for multiphysics research of expansive clays-based buffer and backfill for the KRS repository.

Enhanced device efficiency in organic light-emitting diodes by dual oxide buffer layer

Jesuraj, P. Justin,Hafeez, Hassan,Rhee, Sang Ho,Kim, Dong Hyun,Lee, Jong Chan,Lee, Won Ho,Choi, Dae Keun,Song, Aeran,Chung, Kwun-Bum,Song, Myungkwan,Kim, Chang Su,Ryu, Seung Yoon Elsevier 2018 ORGANIC ELECTRONICS Vol.56 No.-

<P><B>Abstract</B></P> <P>We have demonstrated an improvement in device performance of fluorescent organic light-emitting diodes (OLEDs) by inserting a dual anode buffer layer composed of tungsten oxide (WO<SUB>3</SUB>) and molybdenum oxide (MoO<SUB>3</SUB>). The advantage of adding dual anode buffer layers with different deposition sequences over individual and composite oxide buffer layers has been systematically analyzed based on their electronic and optical properties. The incorporation of single and composite buffer layers has been revealed to induce a very low injection barrier for holes in tri-layer fluorescent OLEDs which results in a charge imbalance in the emission layer. In contrast, a proper sequence of buffer layers (WO<SUB>3</SUB>/MoO<SUB>3</SUB>) exhibiting higher contact angle (lower surface energy) and higher surface roughness, together with a step-wise increment of potential barrier leads to a better overall charge balance in the active emission layer. Therefore, an enhanced current efficiency and power efficiency of ∼5.8 cd/A and ∼5.2 lm/W respectively were recorded for the WO<SUB>3</SUB>/MoO<SUB>3</SUB> buffer unit, which was better than the insertion of individual and composite layers.</P> <P><B>Highlights</B></P> <P> <UL> <LI> The dual oxide buffer layers in fluorescent OLEDs have been explored. </LI> <LI> A dual buffer layer consists of tungsten oxide (WO<SUB>3</SUB>)/Molybdenum oxide (MoO<SUB>3</SUB>). </LI> <LI> The increment in hole interface barrier, higher contact angle and surface roughness of dual oxide layers is beneficial to achieve improved charge balance. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

가격 공정성 지각에 관한 비교연구

이령나,이성근 한국기업경영학회 2009 기업경영연구 Vol.16 No.3

The price fairness perception of the product is closely related to the reference price. If price of the product is higher than reference price, consumer will perceive it as unfair. As previously reported, the principles of price fairness perception such as dual entitlement theory, cost-plus rule and buffer rule have been discussed by many researchers. Dual entitlement theory means that both buyer and seller has the right. That is to say, sellers have the right to obtain the profit and sellers have the right not to buy when the price is not fair. On the other had, consumers will judge the price ad fair when the price is set on the cost level. Buffer rule means that consumers will judge the price as fair when the price should be constant without considering the fluctuation of the cost level. Kahneman et al.(1986a, b) is the first researcher who applied the dual entitlement theory to the price fairness perception. However, Urbany et al.(1989) also supported partially the effectiveness of the dual entitlement theory. That is, he showed that dual entitlement theory will be valid when the search cost is lower than the amount of price increase. But Kalpurkal et al.(1991) denied entirely the Kahneman’s conclusion and suggested that the cost-plus rule and buffer rule are more effective than dual entitlement theory. According to previous studies, there was no dominant rules to describe the phenomenon of price fairness perception. Under the above mentioned backgrounds, the purpose of this study is to explain which theory is more explainable in different situations. In order to describe which theory would make sense for perceiving the fairness, three scenarios based on the each theories was built and they were applied to three products such as digital camera, lettuces and aromatics which were selected in the pre-study. The hypothesis was that consumers would perceive the price fairness differently when each of three previous theories was applied to each product. The conditions considered are as follows when the products were selected. Firstly, lettuces represent the condition that the sellers can control the cost and the consumers have negotiation power, Digital cameras represent the condition that the sellers can control the cost, and have even negotiation power. Aromatics express that the seller cannot control the cost and the consumers have the negotiation power. To test the hypothesis, 3(three rules) by 3(three products based on the situations) experimental design was used. Each cell is composed of around 30 students who attend ‘S’ university. They are required to check the degree of fairness after reading the scenarios. We judged the degree of fairness by the number of respondents who checked 4(probably fair), or 5(fair) in 5 point interval scale. <Table 1> Scenarios [표] Contrary to the hypothesis, and similarly to the Kalpurkal et al.(1991), the cost plus rule and the buffer rule are more valid than dual entitlement theory for explaining the price fairness perception. The reason why the contradictive results were shown is as following. Because consumers tend to maximize their own profit, they consider the rules to be beneficial as fairness. <Table 2> Results [표] This study has also some limitations. The manipulation of one of the scenarios did not work well in the main experiment, which is contradictory to the pre-study. The case of aromatics was not manipulated in the main experiment. Thus, I could not check the ideas I developed based on the literature review. Secondly, the meaning of dual entitlement theory was not delivered to the subjects because of the its delicate situation. The some of contradictory result was due to it. 가격 공정성 지각은 소비자들의 제품구매에 영향을 미친다. 선행연구에서 이미 제시되었듯이 소비자들은 쌍방권한원칙(dual entitlement theory), 원가가산원칙(cost-plus rule), 완충원칙(buffer rule)에 근거하여 가격 공정성을 판단한다. Kahneman 등(1986a, b)은 가격공정성 지각원칙 중 쌍방권한원칙에 대해 처음으로 제시하였고 소비자들이 쌍방권한원칙을 적용하여 가격공정성을 판단할 때 더 효과적이라고 하였다. 그러나 Urbany 등(1989)은 Kahneman 등(1986a, b)의 쌍방권한원칙의 효과에 대해 부분적으로 부정하였고 Kalpurkal 등(1991)은 Kahneman 등(1986a, b)의 결론을 완전히 부정하면서 쌍방권한원칙보다 원가가산원칙, 완충원칙이 더 효과적이라는 결론을 제시하였다. 이렇듯 선행연구에 따르면 어느 하나의 원칙이 지배적으로 설명력이 있다고 보기 어려울 정도로 여러 가지 결과들이 혼재되어 있는 것으로 나타났다. 따라서 이 논문에서는 선행연구에서 나타난 결과를 정리하여, 각 공정성지각의 원칙이 어떤 경우에 더 효과적으로 설명이 가능한가를 밝히기 위하여, 각 원칙들이 설명 가능한 세 가지 상황과 제품군을 시나리오로 설정하여 소비자들이 공정성을 지각하는 방법들을 증명하고자 하였다. 선행연구 결과와는 달리 쌍방권한원칙보다는 원가가산원칙, 완충원칙이 가격 공정성을 지각하는데 더 설명력이 있는 것으로 나타났다.

듀얼 트롤리형 컨테이너 크레인의 버퍼공간 분석을 위한 시뮬레이션 연구

최용석,원승환 한국항해항만학회 2009 한국항해항만학회지 Vol.33 No.5

Container crane is main equipment in container terminals and it determines the productivity and the efficiency of container terminals. The typical type of container cranes has the single trolley and one among advanced types of them has the dual trolley. The objective of this paper is to analyze the buffer size of a container crane with the dual trolley in container terminals. We present a simulation model for analysing the buffer space of a container crane with the dual trolley. The buffer space is located between main trolley in sea-side and second trolley in yard-side. We performs various simulation experiments and analyze the buffer size to estimate the required productivity. 컨테이너 크레인은 컨테이너터미널에서 사용되는 주요 장비이면서 컨테이너 크레인의 효율은 컨테이너터미널의 생산성을 결정한다. 컨테이너 크레인의 전형적인 유형은 싱글 트롤리를 가지고 있으며 진보된 유형들 중의 하나가 듀얼 트롤리형이다. 본 논문의 목적은 컨테이너터미널에서 듀얼 트롤리형 컨테이너 크레인의 버퍼 사이즈를 분석하는 것이다. 듀얼 트롤리형 컨테이너 크레인의 버퍼 공간을 분석하기 위한 시뮬레이션 모델을 소개한다. 버퍼 공간은 해측의 메인 트롤리와 야드측의 세컨드 트롤리 사이에 위치한다. 요구 생산성을 추정하기 위해 다양한 시뮬레이션 실험을 수행하여 버퍼 사이즈를 분석한다.

Buffer Scheme Optimization of Epidemic Routing in Delay Tolerant Networks

Jian Shen,모상만,Ilyong Chung,Xingming Sun 한국통신학회 2014 Journal of communications and networks Vol.16 No.6

In delay tolerant networks (DTNs), delay is inevitable;thus, making better use of buffer space to maximize the packetdelivery rate is more important than delay reduction. In DTNs,epidemic routing is a well-known routing protocol. However, epidemicrouting is very sensitive to buffer size. Once the buffer sizein nodes is insufficient, the performance of epidemic routing willbe drastically reduced. In this paper, we propose a buffer schemeto optimize the performance of epidemic routing on the basis of theLagrangian and dual problem models. By using the proposed optimalbuffer scheme, the packet delivery rate in epidemic routing isconsiderably improved. Our simulation results show that epidemicrouting with the proposed optimal buffer scheme outperforms theoriginal epidemic routing in terms of packet delivery rate and averageend-to-end delay. It is worth noting that the improved epidemicrouting needs much less buffer size compared to that of the originalepidemic routing for ensuring the same packet delivery rate. Inparticular, even though the buffer size is very small (e.g., 50), thepacket delivery rate in epidemic routing with the proposed optimalbuffer scheme is still 95.8%, which can satisfy general communicationdemand.

카메라링크 접속을 위한 임베디드 FPGA의 구현

이창수,Lee, Chang-Su 한국전기전자학회 2011 전기전자학회논문지 Vol.15 No.2

최근 들어 공장자동화의 프레임 그래버 분야에서 전통적인 아날로그 인터페이스 대신 고속, 고해상도의 디지털 인터페이스 방식의 카메라로의 전환이 이루어지고 있으며 이들은 카메라링크를 표준으로 채택하고 있다. 본 논문에서는 PC를 사용하지 않는 임베디드 프레임 그래버 테스트베드를 개발하여 영상처리 응용 솔루션을 제공하고자 한다. 따라서 카메라링크 표준의 라인스캔 CCD 카메라와의 접속을 위하여 하드웨어 회로를 설계하였고 VHDL 코드를 이용하여 FPGA를 프로그래밍하였다. 향후 광학영상기 등의 의료영상, 머신비젼, 산업전자 등의 다양한 영상처리에 본 칩을 이용할 수 있을 것이다. Although conventional analog linescan cameras are used widely, high-speed, high-resolution Cameralink standard will lead the area of frame grabber industry such as factory automation. In this paper, we are developing embedded frame grabber testbed without PC which will give an another solution to image processing applications. Therefore, we designed hardware schematics and programmed FPGA device with VHDL in order to interface Cameralink standard linescan CCD camera. In the future, our embedded on-chip controller could be applied to various image processing systems such as medical imaging, especially optical coherence tomography, machine vision and industrial electronics.

가상 I/O 세그먼트를 이용한 OneNAND 플래시 메모리의 읽기 성능 향상 기법

현승환(Hyun Seunghwan),고건(Koh Kern) 한국정보과학회 2008 정보과학회 컴퓨팅의 실제 논문지 Vol.14 No.7

OneNAND 플래시는 NAND 플래시와 NOR 플래시의 장점을 모두 가진 고성능 하이브리드 플래시 메모리이다. OneNAND 플래시는 NAND 플래시의 장점들을 그대로 가지고 있을 뿐 아니라, 그동안 NAND 플래시의 단점으로 지적되던 느린 읽기 성능을 획기적으로 개선하였다. 그 결과 OneNAND 플래시는 휴대폰 및 디지털 카메라, PMP, 휴대용 게임기와 같은 고성능 휴대용 정보기기를 위한 최적의 스토리지 솔루션으로 각광받고 있다. 하지만 Linux를 비롯하여 현재 사용되고 있는 대부분의 범용 운영체제들은 가상 메모리와 블록 I/O 계층 구조의 제약으로 인해 OneNAND 플래시의 뛰어난 읽기 성능을 제대로 활용하지 못하는 문제를 안고 있다. 이에 본 연구에서는 기존의 소프트웨어 계층 구조 하에서 OneNAND 플래시의 읽기 성능을 최대한 활용하기 위한 기법인 가상 I/O 세그먼트의 활용을 제안한다. 실제 구현을 통한 실험 결과는 제안된 기법이 OneNAND 플래시의 읽기 수행 시간을 기존에 비해 최고 54%까지 단축할 수 있음을 증명하였다. OneNAND flash is a high-performance hybrid flash memory that combines the advantages of both NAND flash and NOR flash. OneNAND flash has not only all virtues of NAND flash but also greatly enhanced read performance which is considered as a downside of NAND flash. As a result, it is widely used in mobile applications such as mobile phones, digital cameras, PMP, and portable game players. However, most of the general purpose operating systems, such as Linux, can not exploit the read performance of OneNAND flash because of the restrictions imposed by their virtual memory system and block I/O architecture. In order to solve that problem, we suggest a new approach called virtual I/O segment. By using virtual I/O segment, the superior read performance of OneNAND flash can be exploited without modifying the existing block I/O architecture and MTD subsystem. Experiments by implementations show that this approach can reduce read latency of OneNAND flash as much as 54%.