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검색결과 166건 처리시간 0.025초

The effect of 4,4'-bis(N,N-diethylamino)benzophenone on the degree of conversion in liquid photopolymer for dental 3D printing

  • Lee, Du-Hyeong;Mai, Hang Nga;Yang, Jin-Chul;Kwon, Tae-Yub
    • The Journal of Advanced Prosthodontics
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    • 제7권5호
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    • pp.386-391
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    • 2015
  • PURPOSE. The purpose of this preliminary study was to investigate the effects of adding 4,4'-bis(N,N-diethylamino) benzophenone (DEABP) as a co-initiator to a binary photoinitiating system (camphorquinone-amine) to analyze on the degree of conversion (DC) of a light-cured resin for dental 3D printing. MATERIALS AND METHODS. Cylindrical specimens (N=60, n=30 per group, ${\phi}5mm{\times}1mm$) were fabricated using bisphenol A glycerolate dimethacrylate (BisGMA) both with and without DEABP. The freshly mixed resins were exposed to light in a custom-made closed chamber with nine light-emitting diode lamps (wavelength: 405 nm; power: $840mW/cm^2$) for polymerization at each incidence of light-irradiation at 10, 30, 60, 180, and 300 seconds, while five specimens at a time were evaluated at each given irradiation point. Fourier-transform infrared (FTIR) spectroscopy was used to measure the DC values of the resins. Two-way analysis of variance and the Duncan post hoc test were used to analyze statistically significant differences between the groups and given times (${\alpha}$=.05). RESULTS. In the DEABP-containing resin, the DC values were significantly higher at all points in time (P<.001), and also the initial polymerization velocity was faster than in the DEABP-free resin. CONCLUSION. The addition of DEABP significantly enhanced the DC values and, thus, could potentially become an efficient photoinitiator when combined with a camphorquinone-amine system and may be utilized as a more advanced photopolymerization system for dental 3D printing.

Detection of tension force reduction in a post-tensioning tendon using pulsed-eddy-current measurement

  • Kim, Ji-Min;Lee, Jun;Sohn, Hoon
    • Structural Engineering and Mechanics
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    • 제65권2호
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    • pp.129-139
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    • 2018
  • Post-tensioning (PT) tendons are commonly used for the assembly of modularized concrete members, and tension is applied to the tendons during construction to facilitate the integrated behavior of the members. However, the tension in a PT tendon decreases over time due to steel corrosion and concrete creep, and consequently, the stress on the anchor head that secures the PT tendon also diminishes. This study proposes an automatic detection system to identify tension reduction in a PT tendon using pulsed-eddy-current (PEC) measurement. An eddy-current sensor is installed on the surface of the steel anchor head. The sensor creates a pulsed excitation to the driving coil and measures the resulting PEC response using the pick-up coil. The basic premise is that the tension reduction of a PT tendon results in stress reduction on the anchor head surface and a change in the PEC intensity measured by the pick-up coil. Thus, PEC measurement is used to detect the reduction of the anchor head stress and consequently the reduction of the PT tendon force below a certain threshold value. The advantages of the proposed PEC-based tension-reduction-detection (PTRD) system are (1) a low-cost (< $ 30), low-power (< 2 Watts) sensor, (2) a short inspection time (< 10 seconds), (3) high reliability and (4) the potential for embedded sensing. A 3.3 m long full-scale monostrand PT tendon was used to evaluate the performance of the proposed PTRD system. The PT tendon was tensioned to 180 kN using a custom universal tensile machine, and the tension was decreased to 0 kN at 20 kN intervals. At each tension, the PEC responses were measured, and tension reduction was successfully detected.

실시간 2차원 디지털 IIR 필터의 구현 (Single Board Realtime 2-D IIR Filtering System)

  • 정재길
    • 공학논문집
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    • 제2권1호
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    • pp.39-47
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    • 1997
  • 실시간 2차원 디지털 IIR 필터링 알고리즘의 구현을 가능하게 하는 디지털 신호처리시스템의 효율적인 구조를 제안하였다. 제안된 구조는 시스템 레벨과 프로세서 레벨에서의 병렬처리를 통하여 높은 시스템 성능을 가능하게 하였다. 프로세서간의 데이터 통신의 양을 크게 줄였으며 시스템이 초기화된 이후에는 다른 오버헤드 없이 계산을 수행할 수 있도록 설계하여 전체 시스템의 효율을 극대화하였다. 기능 레벨의 시뮬레이션을 수행하였으며, 그 결과 1 사이클당 1개의 데이터를 처리할 수 있음을 확인하였다. 이는 단지 10MHz의 시스템 클럭을 사용하는 경우 2차원 4차 IIR필터를 실시간 비디오데이터에 적용할 수 있음을 의미하며, 시스템 클럭의 주파수를 올릴 경우 고선명 TV (HDTV) 등의 전후 처리 필터로 사용가능 할 것이다.

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Nonlinear transient analysis of FG pipe subjected to internal pressure and unsteady temperature in a natural gas facility

  • Soliman, Ahmed E.;Eltaher, Mohamed A.;Attia, Mohamed A.;Alshorbagy, Amal E.
    • Structural Engineering and Mechanics
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    • 제66권1호
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    • pp.85-96
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    • 2018
  • This study investigates the response of functionally graded (FG) gas pipe under unsteady internal pressure and temperature. The pipe is proposed to be manufactured from FGMs rather than custom carbon steel, to reduce the erosion, corrosion, pressure surge and temperature variation effects caused by conveying of gases. The distribution of material graduations are obeying power and sigmoidal functions varying with the pipe thickness. The sigmoidal distribution is proposed for the 1st time in analysis of FG pipe structure. A Two-dimensional (2D) plane strain problem is proposed to model the pipe cross-section. The Fourier law is applied to describe the heat flux and temperature variation through the pipe thickness. The time variation of internal pressure is described by using exponential-harmonic function. The proposed problem is solved numerically by a two-dimensional (2D) plane strain finite element ABAQUS software. Nine-node isoparametric element is selected. The proposed model is verified with published results. The effects of material graduation, material function, temperature and internal pressures on the response of FG gas pipe are investigated. The coupled temperature and displacement FEM solution is used to find a solution for the stress displacement and temperature fields simultaneously because the thermal and mechanical solutions affected greatly by each other. The obtained results present the applicability of alternative FGM materials rather than classical A106Gr.B steel. According to proposed model and numerical results, the FGM pipe is more effective in natural gas application, especially in eliminating the corrosion, erosion and reduction of stresses.

DEVELOPMENT AND IMPLEMENTATION OF DISTRIBUTED HARDWARE-IN-THE-LOOP SIMULATOR FOR AUTOMOTIVE ENGINE CONTROL SYSTEMS

  • YOON M.;LEE W.;SUNWOO M.
    • International Journal of Automotive Technology
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    • 제6권2호
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    • pp.107-117
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    • 2005
  • A distributed hardware-in-the-loop simulation (HILS) platform is developed for designing an automotive engine control system. The HILS equipment consists of a widely used PC and commercial-off-the-shelf (COTS) I/O boards instead of a powerful computing system and custom-made I/O boards. The distributed structure of the HILS system supplements the lack of computing power. These features make the HILS equipment more cost-effective and flexible. The HILS uses an automatic code generation extension, REAL-TIME WORKSHOP$^{ (RTW$^{) of MATLAB$^{ tool-chain and RT-LAB$^{, which enables distributed simulation as well as the detection and generation of digital event between simulation time steps. The mean value engine model, which is used in control design phase, is imported into this HILS. The engine model is supplemented with some I/O subsystems and I/O boards to interface actual input and output signals in real-time. The I/O subsystems are designed to imitate real sensor signals with high fidelity as well as to convert the raw data of the I/O boards to the appropriate forms for proper interfaces. A lot of attention is paid to the generation of a precise crank/ earn signal which has the problem of quantization in a conventional fixed time step simulation. The detection of injection! command signal which occurs between simulation time steps are also successfully compensated. In order to prove the feasibility of the proposed environment, a simple PI controller for an air-to-fuel ratio (AFR) control is used. The proposed HILS environment and I/O systems are shown to be an efficient tool to develop various control functions and to validate the software and hardware of the engine control system.

Structural health monitoring of a cable-stayed bridge using smart sensor technology: deployment and evaluation

  • Jang, Shinae;Jo, Hongki;Cho, Soojin;Mechitov, Kirill;Rice, Jennifer A.;Sim, Sung-Han;Jung, Hyung-Jo;Yun, Chung-Bangm;Spencer, Billie F. Jr.;Agha, Gul
    • Smart Structures and Systems
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    • 제6권5_6호
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    • pp.439-459
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    • 2010
  • Structural health monitoring (SHM) of civil infrastructure using wireless smart sensor networks (WSSNs) has received significant public attention in recent years. The benefits of WSSNs are that they are low-cost, easy to install, and provide effective data management via on-board computation. This paper reports on the deployment and evaluation of a state-of-the-art WSSN on the new Jindo Bridge, a cable-stayed bridge in South Korea with a 344-m main span and two 70-m side spans. The central components of the WSSN deployment are the Imote2 smart sensor platforms, a custom-designed multimetric sensor boards, base stations, and software provided by the Illinois Structural Health Monitoring Project (ISHMP) Services Toolsuite. In total, 70 sensor nodes and two base stations have been deployed to monitor the bridge using an autonomous SHM application with excessive wind and vibration triggering the system to initiate monitoring. Additionally, the performance of the system is evaluated in terms of hardware durability, software stability, power consumption and energy harvesting capabilities. The Jindo Bridge SHM system constitutes the largest deployment of wireless smart sensors for civil infrastructure monitoring to date. This deployment demonstrates the strong potential of WSSNs for monitoring of large scale civil infrastructure.

1930년대 중국 문서당안 행정개혁론의 이해 (The Records and Archives Administrative Reform in China in 1930s)

  • 이원규
    • 기록학연구
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    • 제10호
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    • pp.276-322
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    • 2004
  • Historical interest in China in 1930s has been mostly focused on political characteristic of the National Government(國民政府) which was established by the KMT(中國國民黨) as a result of national unification. It is certain that China had a chance to construct a modern country by the establishment of the very unified revolutionary government. But, it was the time of expanding national crises that threatened the existence of the country such as the Manchurian Incident and the Chinese-Japanese War as well as the chaos of the domestic situation, too. So it has a good reason to examine the characteristic and pattern of the response of the political powers of those days. But, as shown in the recent studies, the manifestation method of political power by the revolutionary regime catches our attention through the understanding of internal operating system. Though this writing started from the fact that the Nationalist Government executed the administrative reform which aimed at "administrative efficiency" in the middle of 1930s, but it put stress on the seriousness of the problem and its solution rather than political background or results. "Committee on Administrative Efficiency(行政效率委員會)", the center of administrative reform movement which was established in 1934, examined the plan to execute the reform through legislation by the Executive Council(行政院) on the basis of the results of relevant studies. They claimed that the construction of a modern country should be performed by not political revolution anymore but by gradual improvement and daily reform, and that the operation of the government should become modern, scientific and efficient. There were many fields of administrative reform subjects, but especially, the field of records and archives adminstration(文書檔案行政) was studied intensively from the initial stage because that subject had already been discussed intensively. They recognized that records and archives were the basic tool of work performance and general activity but an inefficient field in spite of many input staff members, and most of all, archival reform bring about less conflicts than the fields of finance, organization and personnel. When it comes to the field of records adminstration, the key subjects that records should be written simply, the process of record treatment should be clear and the delay of that should be prevented were already presented in a records administrative meeting in 1922. That is, the unified law about record management was not established, so each government organization followed a conventional custom or performed independent improvement. It was through the other records administrative workshop of the Nationalist Government in 1933 when the new trend was appeared as the unified system improvement. They decided to unify the format of official records, to use marker and section, to unify the registration of receipt records and dispatch records and to strengthen the examination of records treatment. But, the method of records treatment was not unified yet, so the key point of records administrative reform was to establish a unified and standard record management system for preventing repetition by simplifying the treatment procedure and for intensive treatment by exclusive organizations. From the foundation of the Republic of China to 1930s, there was not big change in the field of archives administration, and archives management methods were prescribed differently even in the same section as well as same department. Therefore, the point at issue was to centralize scattered management systems that were performed in each section, to establish unified standard about filing and retention period allowance and to improve searching system through classification and proper number allowance. Especially, the problem was that each number system and classification system bring about different result due to dual operation of record registration and archives registration, and that strict management through mutual contrast, searching and application are impossible. Besides, various problems such as filing tools, arrangement method, preservation facilities & equipment, lending service and use method were raised also. In the process this study for the system improvement of records and archives management, they recognized that records and archives are the identical thing and reached to create a successive management method of records and archives called "Records and Archives Chain Management Method(文書檔案連鎖法)" as a potential alternative. Several principles that records and archives management should be performed unitedly in each organization by the general record recipient section and the general archives section under the principle of task centralization, a consistent classification system should be used by classification method decided in advance according to organizational constitution and work functions and an identical number system should be used in the process of record management stage and archive management stage by using a card-type register were established. Though, this "Records and Archives Chain Management Method" was developed to the stage of test application in several organizations, but it was not adopted as a regular system and discontinued. That was because the administrative reform of the Nationalist Government was discontinued by the outbreak of the Chinese-Japanese War. Even though the administrative reform in the middle of 1930s didn't produce practical results but merely an experimentation, it was verified that the reform against tradition and custom conducted by the Nationalist Government that aimed for the construction of a modern country was not only a field of politics, but on the other hand, the weak basis of the government operation became the obstacle to the realization of the political power of the revolutionary regime. Though the subject of records and archives administrative reform was postponed to the future, it should be understood that the consciousness of modern records and archives administration and overall studies began through this examination of administrative reform.

KNIME 분석 플랫폼 기반 스마트 미터 빅 데이터 클러스터링 (Clustering of Smart Meter Big Data Based on KNIME Analytic Platform)

  • 김용길;문경일
    • 한국인터넷방송통신학회논문지
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    • 제20권2호
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    • pp.13-20
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    • 2020
  • 빅 데이터 관련 주요 논제 중의 하나는 방대한 시간 기반 또는 원격 측정 데이터의 가용성에 관한 문제이다. 현재 저비용 획득 및 저장 장치의 등장은 더 세밀한 분석에 사용될 상세한 시간 데이터를 얻을 수 있어서 배후 시스템에 대해 여러 가지 지식을 갖거나 미래의 이벤트를 더 정확히 예측할 수 있다. 특히, 스마트 미터가 설치된 수많은 가정 및 기업 등을 대상으로 전기 사용에 관한 고객 맞춤형 계약을 정의하는 것은 다른 무엇보다도 중요한 문제이다. 수많은 스마트 미터 데이터를 바탕으로 공통적인 전력 소비 형태를 몇 가지 그룹으로 구분할 필요가 있다. 이에 본 연구에서는 스마트 미터 측정 관련 공개 데이터와 자바 기반 공개 소스인 KNIME 플랫폼을 사용하여 스마트 미터 관련 빅 데이터 변환과 클러스터링을 나타낸다. 빅 데이터 구성 요소는 공개 소스는 아니지만, 시험판으로 사용할 수 있다. 스마트 미터 빅 데이터를 가져오고, 정리하고, 변환한 후 전력 사용량 행위와 관련된 각 미터 ID의 해석과 클러스터링에 적합한 DTW 접근 방식을 통해 전력 사용 행위에 관한 스마트 계약을 정의할 수 있다.

감염 조절용 차단막의 두께가 광중합기의 중합광에 미치는 영향 (Effect of infection control barrier thickness on light curing units)

  • 장훈상;이석련;홍성옥;류현욱;송창규;민경산
    • Restorative Dentistry and Endodontics
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    • 제35권5호
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    • pp.368-373
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    • 2010
  • 연구목적: 본 연구는 감염 조절용 차단막을 여러 겹으로 사용했을 때 광중합기의 광강도와 파장, light diffusion 등에 미치는 영향에 대해 조사하였다. 연구 재료 및 방법: 감염 조절용 차단막은 투명 랩 (크린랩)을 사용하였고 광중합기는 할로겐 광중합기 (Optilux 360)와 LED 광중합기 (Elipar FreeLight 2)를 사용하였다. 차단막을 1겹, 2겹, 4겹, 8겹으로 광중합기의 광섬유말단을 감싸고 휴대용 광강도 측정기 (Cure Rite)로 광중합기의 광강도를 측정하였다. 광중합기를 주문제작한 optical breadboard에 고정시킨 후 휴대용 spectroradiometer (CS-1000)를 이용하여 광중합기의 파장을 측정하였고, DSLR (Nikon D70s)을 이용하여 광중합기의 light diffusion을 사진 촬영하였다. 결과: 광강도 측정 결과는 차단막의 두께가 증가할수록 광강도가 유의하게 감소하였으나 할로겐 광중합기에서 1겹과 2겹 사이에는 유의차가 없었으며, 4겹 이상의 차단막을 투과할 때 광강도가 더 많이 감소하였다. 여러 겹의 차단막을 투과한 광중합기의 전체적인 파장 형태와 peak wavelength의 변화는 관찰되지 않았다. Light diffusion 사진 촬영 시, LED 광중합기에서는 차단막의 두께가 미치는 영향이 없었으나 할로겐 광중합기에서는 차단막을 4겹 사용했을 때부터 중합광이 조사되는 각도가 감소하기 시작하여 8겹 사용했을 때 통계적으로 유의하게 감소하는 것을 볼 수 있었다 (p < 0.05). 결론: 광중합형 복합레진을 광중합할 경우 감염 조절용 차단막이 찢어지는 경우를 대비하여 1겹으로 사용하기 보다는 2겹으로 사용하는 것이 환자간의 교차감염을 예방하는데 유리할 것으로 사료된다.

Interleukin 10 rs1800872 T>G Polymorphism was Associated with an Increased Risk of Esophageal Cancer in a Chinese Population

  • Sun, Jia-Ming;Li, Qiong;Gu, Hai-Yong;Chen, Yi-Jang;Wei, Ji-Shu;Zhu, Quan;Chen, Liang
    • Asian Pacific Journal of Cancer Prevention
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    • 제14권6호
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    • pp.3443-3447
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    • 2013
  • Aim: Esophageal cancer is the eighth most common cancer and sixth leading cause of cancer associated death worldwide. The 5 year survival rate for esophageal cancer patients is very poor and accounts for only 12.3%. Besides environmental risk factors, genetic factors might play an important role in the esophageal cancer carcinogenesis. Methods: We conducted a hospital based case-control study to evaluate the genetic effects of functional single nucleotide polymorphisms (SNPs): interleukin 9 (IL9) rs31563 C>T, IL9 rs31564 G>T, IL10 rs1800872 T>G, IL12A rs2243115 T>G, IL12B rs3212227 T>G and IL13 rs1800925 C>T on the development of esophageal cancer. A total of 380 esophageal squamous cell carcinoma (ESCC) cases and 380 controls were recruited for this study. The genotypes were determined using a custom-by-design 48-Plex SNPscan$^{TM}$ Kit. Results: The IL10 rs1800872 T>G polymorphism was associated with an increased risk of ESCC. However, there were no significant links with the other five SNPs. Stratified analyses indicated no significant risk of ESCC associated with the IL10 rs1800872 T>G polymorphism evident among any subgroups. Conclusion: These findings indicated that functional polymorphism IL10 rs1800872 T>G might contribute to ESCC susceptibility. However, our results were obtained with a limited sample size, so that the power of our analysis was low. Future larger studies with more rigorous study designs of other ethnic populations are required to confirm the current findings.