• Proceedings of the Korea Concrete Institute Conference
• /
• 1996.10a
• /
• pp.101-107
• /
• 1996

In this study, the wedge splitting test (WST) specimens with various strength levels were tested to investigate the fatigue crack growth behavior of concrete. Selected test variables were concrete compressive strength with 2 levels (28 MPa, 60 MPa, 100 MPa) and maximum fatigue loading with 2 levels (75%, 85%). Fatigue testing was preceded by fracture energy test and the crack growth was measured by means of the compliance calibration method, 60 WST specimens were cast for the fatigue test, and 6 companion cylinders ($\phi$100${\times}$ 200 mm) for each batch. In fatigue test, the frequency of loading cycle was 1 Hz, and the minimum fatigue loading level was 5~10 % of ultimate monotonic loading. On the basis of the experimental results, a fracture mechanics-based empirical relationships for fatigue crack growth rate (da/dN-$\Delta$KI relationships) were presented. In addition, the effect of initial notch depth on the fracture energy and the validity of compliance calibration technique for the WST were shown.

• The Journal of Korean Academy of Prosthodontics
• /
• v.52 no.2
• /
• pp.97-104
• /
• 2014

This study was aimed to compare the radiopacity of four kinds of currently available resin based implant cements using digital radiography. Materials and Methods: Four resin-based implant cements((Estemp $Implant^{TM}$ (Spident, Incheon, Korea), $Premier^{(R)}$Implant (Premier, Pennsylvania, USA), $Cem-Implant^{TM}$ (B.J.M lab, Or-yehuda, Israel), $InterCem^{TM}$ (SCI-PHARM, California, USA)) and control group (Elite Cement $100^{TM}$ (GC, Tokyo, Japan) ) were mixed and cured according to the manufacturer's instructions on the custom made split-type metal mold. A total of 150 specimens of each cement were prepared and each specimen (purity over 99%) was placed side-by-side with an aluminum step wedge for image taking with Intraoral X-ray unit (Esx, Vatech, Korea) and digital X-ray sensor (EzSensor, Vatech, Korea). For the evaluation of aluminum wedge equivalent thickness (mm Al), ImageJ 1.47 m (Wayne Rasband, National Institutes of Health, USA) and Color inspector 3D ver 2.0 (Interaktive Visualisierung von Farbraumen, Berlin, Germany) programs were used. Result: Among the 5 cements, Elite cement $100^{TM}$ (control group) showed the highest radio-opacity in all thickness. In the experimental group, $InterCem^{TM}$ had the highest radio-opacity followed by $Premier^{(R)}$ Implant $Cement^{TM}$, $Cem-Implant^{TM}$ and Estemp $Implant^{TM}$. In addition, $InterCem^{TM}$ showed radio-opacity that met the ISO No. 4049 standard in all the tested specimen thickness. Cem-Implant on 0.5 mm thickness showed radiopacity that met the ISO No. 4049 standard. Conclusion: Among the implant resin-based cements tested in the study, $Premier^{(R)}$ Implant Cement and Estemp $Implant^{TM}$ did not show appropriate radio-opacity. Only $InterCem^{TM}$ and $Cem-Implant^{TM}$ 0.5 mm specimen had the proper radiopacity and met the experiment standard.

• Journal of dental hygiene science
• /
• v.6 no.2
• /
• pp.93-99
• /
• 2006

This study was carried out to investigate practical application status of oral hygiene devices through making a survey of labor of the D industrial company-about carefully curing oral disease in home, the status of practical application of tooth brush, the status of practical application of fluoridated toothpaste, status of practical application of auxiliary oral hygiene devices, a motive use or unuse of auxiliary oral hygiene devices. 1. In home, carefully curing oral disease is dental caries(62.4%). 2. Status of practical application toothbrush showed the highest user ratio of mideum size(79.6%). 3. Showed the highest user ratio of horizontal plane toothbrush(73.5%). 4. Answerd don't take a prudent attitued in choice of fluoridated toothpaste(73.5%). 5. In the status of reconition of oral hygiene devices, showed the highest user ratio of eletric toothbrush(77.0%). 6. In the status of reconition of auxiliary oral hygiene devices, showed the highest user ratio of wooden wedge stimulator(89.4%)and gargle liquid(84.5%). In using of oral hygiene devices, showed the highest user ratio of electric toothbrush(13.3%), toohbrush for periodontal patients(2.7%). In using of auxiliary, wooden wedge stimulator (58.4%)and gargle liquid(41.2%). In effect using of oral hygiene devices showed the highest user ratio of denture brush(50.0%)and eletric toothbrush(43.3%), in effect using of auxiliary oral hygiene devices showed the highest user ratio of water pick(80.0%) and dental floss(75.8%). 6. A motive of the use auxiliary oral hygiene device is choice by oneself through TV, advertisement, public information(57.6%), and the reason-they don't use of auxiliary oral hygiene devicebecause of they don't know proper to them the kind of auxiliary oral hygiene device.

• Korean Journal of Head & Neck Oncology
• /
• v.16 no.2
• /
• pp.167-171
• /
• 2000

Objectives: To compare the outcomes of treatment with a focus on the effectiveness of the two primary techniques of radiation used for treating parotid gland malignancies. Materials and Methods: A retrospective analysis of 70 patients with parotid gland cancer treated between 1981-1997. Radiation was delivered through an ipsilateral field of high energy electron and photon in 37 patients(52.9%). Two wedge paired photon was used to treat in 33 patients(47.1%). The median dose was 60 Gy, typically delivered at 1.8-2.0Gy per fraction. The median follow-up times for surviving patients was 60 months. Results: The overall and disease free 5 year survival rates were 71.6% and 69.5%, respectively. Wedge paired photon and photon-electron treatment disease tree 5 year survival rates were 61.1% and 80.5%, respectively. Overall local failure rate was 18.6%. Local failure rate of wedge paired photon technique was higher than that of mixed beam technique. Late complication rate was 37.1%, but most of them were mild grade. Conclusion: Techniques of radiation were associated with local control. The technique of using an ipsilateral field encompassing the parotid bed and treated with high energy electrons often mixed photons was effective with minimal severe late toxicity. To irradiate deep sited tumors, we consider 3-D conformal treatment plan for well encompassing the target volume.

• The Korean Journal of Nuclear Medicine Technology
• /
• v.21 no.2
• /
• pp.65-73
• /
• 2017

Purpose 3D 프린팅 기술은 3D 스캔이나 모델링을 통하여 적측가공 방식으로 제작하는 기공기술로서 금형 없이 직접 생산이 가능하고 빠른 시간 내에 제작이 가능하여 최근 다양한 산업분야에서 본격적으로 적용되고 있다. 3D 프린팅 기술은 의료분야에 있어, 영상의학 및 방사선 치료분야에서 다양하게 활용되고 있지만 핵의학 분야에서는 관련 연구가 미비한 실정이다. 그러므로 본 연구는 기존에 적용되고 있는 핵의학분야 팬텀과 3D 프린팅 기술로 제작된 텀의 특성을 비교하고 적용 가능성을 평가하는데 목적을 두었다. Materials and Methods 방사선 투과도 변화측정 국제기준 팬텀인 알루미늄(Aluminum) 계단 쐐기(step wedge)를 기준($140mm{\times}62mm{\times}35mm$)으로 PMMA(Poly Methyl Meta Acrylate)와 ABS(Acrylonitrile Butadiene Styrene)재질로 각각 동일한 크기의 팬텀을 제작하였다. PMMA 팬텀은 핵의학 분야에서 주로 적용되는 팬텀의 성분과 동일한 소재로 제작하였고, ABS 팬텀 제작은 3D 프린팅 기술의 액체 기반형의 SLA(Stereo Lithography Apparatus)기법을 사용하여 제작하였다. 본 연구는 SPECT/CT장비 BrightView XCT(Philips Health Care, Cleveland, USA)를 이용하였다. 영상 획득은 Rectangular Flood phantom(Biodex, New York, USA) $^{99m}TcO_4$ 3, 6 mCi와 $^{57}Co$ lood phantom(adqual, New Hampshire, USA) $^{57}Co$ 20 mCi를 이용하여 Aluminum, PMMA, ABS 팬텀에 대해 60 min 리스트모드(List mode)로 획득하였다. 획득한 영상의 분석을 위해 관심영역(ROI)을 설정하여 각 팬텀의 단계별로 평가하였다. Results 방사선원의 종류 및 방사선량에 따라 ABS 팬텀의 계수치는 PMMA 팬텀의 계수치와 유사한 값을 나타내며, 두께의 증가에 따라 선형적으로 감소하였다. Aluminum, PMMA, ABS 팬텀의 선감약계수를 비교했을 때, Aluminum 팬텀의 선감약계수는 나머지 두 팬텀보다 수치가 높았고, PMMA, ABS 팬텀에서는 근사치의 선감약계수가 나타났다. Conclusion 3D 프린팅 기술로 제작된 ABS 팬텀을 기준으로 PMMA 팬텀은 두께가 증가함에 따른 계수치의 변화가 유사하게 선형적으로 감소하였고, 선감약계수도 근사치로 나타내었다. ABS 팬텀의 핵의학적 적용 가능성을 확인할 수 있었으며, 추후 연구를 통해 세부적인 교정치(correction value)를 적용한다면 활발한 적용이 가능하리라 사료된다.

• Biomolecules & Therapeutics
• /
• v.6 no.2
• /
• pp.199-203
• /
• 1998

Acute hemodynamic effects of CJ-18513, a non-peptide angiotensin IIreceptor antagonist, were examined in mongrel dogs treated with high frequency ventricular pacing for one week. Rapid ventricular pacing reduced mean blood pressure (mBP), Lvdp/dt and cardiac output (CO), and increased the left ventricular end-diastolic pressure (LVEDP) and pulmonary capillary wedge pressure (PCWP). Continuous infusion of CJ-10513 at doses of 10 and 20$\mu$g/kg/min, respectively, for 30 minutes reduced mBP, LVEDP and myocardial oxygen consumption rate (MVO,) and shifted the cardiac function curve (CO-LVEDP ourve) to the left in this dog model. In conclusion, CJ-10513 decreased the preload and afterload and increased the cardiac function in dogs with pacing-induced heart failure.

• The Transactions of the Korean Institute of Electrical Engineers B
• /
• v.53 no.5
• /
• pp.318-324
• /
• 2004

In the recently, the necessity of linear position control motors have been increased in the various fields of the automatic control system. In this paper, we have designed the tooth models of the hybrid type linear stepping motor(HLSM); rectangular type(RT), triangle type(TrT), round type(RdT) and wedge type(WT), and proposed the optimum tooth shape of the HLSM by simulating(Flux2D) the thrust and normal force characteristics with the finite element method(FEM) and the virtual work method. And we have manufactured the prototype HLSM with the optimum tooth, and measured the various values by using experimental system. Thus, we have confirmed the justice of theory because the computed and the experimental results almost coincide with.

• Journal of Ocean Engineering and Technology
• /
• v.32 no.4
• /
• pp.261-271
• /
• 2018

In this study, a hydraulic model test, to which Particle Image Velocimetry (PIV) system applied, was used to determine the hydrodynamic characteristics of the advection-diffusion of saltwater according to bottom conditions (impermeable/permeability, diameter, and inclination) and the difference of the initial salt. Considering quantitative and qualitative results from the experiment, the characteristics of the density current were discussed. As an experimental result, the advection-diffusion mechanism of salinity was examined by the shape of saltwater wedge and the flow structure of density currents with various bottom conditions. The vertical salt concentration obtained from the experiment was used as quantitative data to calculate the diffusion coefficient that was used in the numerical model of the advection-diffusion of saltwater.

• Journal of the Korean Society for Nondestructive Testing
• /
• v.10 no.2
• /
• pp.56-62
• /
• 1990

Surface Acoustic Waves(SAW) are generated on silicon wafer and $YZ-LiTaO_3$ substrate and are detected by noncontact method. As wave sources two kinds of transducers are used : the wedge-type of 20.0 MHz and fabricated Interdigital Transducer(IDT) of 20.8 MHz. SAW are modulated by the optical chopper frequency and are syncronized with a laser beam. In signal processing, intensity variations of light due to the intensity of SAW are analyzed using lock- in amplifier. From the results, corresponding to the applied input power, the intensity variations of a deflected light by corrugations on the substrates are increased and saturation phenomenon is observed.

• Proceedings of the Acoustical Society of Korea Conference
• /
• autumn
• /
• pp.303-306
• /
• 2000

복잡한 형상을 지닌 터빈 블래이드의 결함을 검사하기 위해 현재 $35^\circ,\; 38^\circ,\; 40^\circ$의 횡파 굴절각을 지닌 탐촉자를 사용하고 있다. 이와 같은 굴절각은 초음파 빔의 경로를 Snell의 법칙에 의해 설정하고 있다. 그러나 터빈 블래이드 검사용 초음파 탐촉자를 제작하는 과정에서 $35^\circ$의 횡파 굴절각을 갖는 경사각 탐촉자는 제작이 어려움을 알았다. 이러한 원인은 철강재료의 종파임계각이 $33.2^\circ$의 횡과굴절각에 대응되며, 종파임계각 근처에서는 전반사 현상 때문에 에너지 투과율이 매우 작아 실제 시험대상체에 입사되는 에너지가 거의 없으며 또한 횡파굴절각이 약 $37.5^\circ$ 일때에 휭파의 에너지 투과율이 최대가 되어 wedge를 $37.5^\circ$ 이하의 횡파굴절각을 갖도록 설계하더라도 측정을 하면 $37.5^\circ$ 근처의 횡파굴 절각을 갖게된다. 즉, 종파임계각 근처에서는 전반사 현상에 의해 경계면에서의 에너지 투과가 매우 작아 횡파 굴절각은 Snell의 법칙이 아닌 초음파 에너지의 투과 정도를 나타내는 echo transmittance의 크기에 의해 결정된다.