• 전기학회논문지
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• 제58권12호
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• pp.2446-2452
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• 2009

A Ceramic Metal-halide lamp is achieved by adding multiple metals to a basic mercury discharge. Because the vapor pressure of most metals is very much lower than mercury itself, metal-halide salts of the desired metals, having higher vapor pressures, are used to introduce the material into the basic discharge. The metal compounds are usually polyatomic iodides, which vaporize and subsequently dissociate as they diffuse into the bulk plasma. Metals with multiple visible transitions are necessary to achieve high photometric efficiency and good color. Compounds of Sc, Dy, Ho, Tm, Ce, Pr, Yb and Nd are commonly used. The maximum visible efficacy of a Ceramic Metal Halide lamp, under the constant of a white light source, is predicted to be about 450lm/W. This is controlled principally by the chemical fill chosen for a particular lamp. Current these lamps achieve 130lm/W and these life time are the maximum 16,000[hr]. So factors of performance lower are necessary to improve lamp performance. In this paper, we analyzed factors of performance lower by accelerated deterioration test. The lamp was operated with short duration turn-on/turn-off procedure to enhance the effect due to electrode sputtering during lamp ignition. The tested lamp that was operated with a longer turn-on/off(20/20 minutes) showed blackening, changed distance between electrodes and lowered color rendering & color temperature by losses of Dy at 421.18nm, I at 511nm, T1 at 535nm and Na at 588nm compared with the new lamp.

• 한국콘텐츠학회논문지
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• 제21권3호
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• pp.602-608
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• 2021

임상에서 사용되는 Co-Cr 합금과 도재 간의 접착 강도를 비교하기 위해 대조군으로 전통적인 주조(Casting) 방법, 실험군으로 Milling(Milling group), SLM(3d printing group) 시편을 제작하여 금속과 도재(ceramic) 간의 접착 강도를 비교 하였다. 합금과 도재간의 접착강도를 측정하기 위해 universal testing machine를 이용하여 3점 굴곡 시험을 시행하고, 결합강도 측정 후 금속-도재간의 계면을 관찰하였다. 금속-도재(ceramic) 간의 실험 결과 casting group 53.59 MPa, milling group 45.90 MPa, 3d printing group 58.34 MPa의 결과값을 보였고, 통계적으로 유의성은 없었다. 파절양상은 두 집단 시편의 대부분이 복합 파절양상(mixed failure)을 보였다. 본 연구는 3D 프린팅로 제작된 합금으로 합금-도재의 결합 강도값을 측정하였을 때 임상적으로 적용 가능한 수치를 보여 주었다.

• 대한치과기공학회지
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• 제34권2호
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• pp.135-143
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• 2012

Purpose: The purpose of this in vitro study was to compare the marginal fit of POM restorations with 3 different thickness of metal coping. Methods: 2.0mm Occlusal reduction, 1.0mm preparation of axial wall with 6degree taper, and chamfer margin was prepared a maxillary first premolar on dentiform. Duplicate prepared die and, make 30 individual dies with Ni-Cr metal. Make 3 groups of 30 press ceramic on Metal crown with different thickness of metal coping; 10 of 0.1mm, 10 of 0.3mm, 10 of 0.5mm thickness metal coping. The marginal fit of the crowns was evaluated 50 points per 1 crown, around the crown margin circumference under a optical microscope at original magnification ${\times}100$. A 1-way analysis of variance (ANOVA) was used to compare data. Results: The mean marginal discrepancy for POM with 0.1mm metal copings was $72.56{\mu}m$, $67.83{\mu}m$ for 0.3mm metal coping POMs, and $72.56{\mu}m$ for 0.5mm metal coping POM. The 1-way ANOVA showed significant difference among 3 groups. Conclusion: The marginal fit of pressed-on-metal (POMs) was best with 0.3mm thickness of metal coping, fallowing by 0.1mm, and 0.5mm in the order.

• 대한치과교정학회지
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• 제37권5호
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• pp.376-385
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• 2007

고정성 장치를 이용한 교정 치료는 심미적 개선이 주목적 중 하나이나, 금속재 브라켓은 치료기간 동안 비심미적으로 보이는 단점이 있다. 이러한 이유로 치아색과 유사한 심미적 브라켓이 선호되었으나 호선과의 마찰저항이 금속재 브라켓보다 큰 것으로 알려져 있다. 본 연구는 최근 개발된 심미적 브라켓의 일종인 인산칼슘재 브라켓의 마찰저항을 측정하고 기존 금속재 브라켓과 금속슬롯 삽입형 도재 브라켓과의 마찰저항의 차이를 구명(究明)해 보고자 하였다. 실험군으로서 인산칼슘 재질의 Hyaline II (Tomy, Tokyo, Japan) 브라켓을, 대조군으로서 metal slot이 삽입된 도자기 재질인 Clarity (3M Unitek, Monrovia, CA, USA) 브라켓과 스테인레스 스틸 금속재 브라켓인 Kosaka (Tomy, Tokyo, Japan) 브라켓을 사용하고, $0.019\;{\times}\;0.025$ 인치 스테인레스 스틸 강선 (3M Unitek, Monrovia, CA, USA)을 이용하며 결찰재는 합성고무링 (Ormco, Glendora, CA, USA)을 사용하였다. 치아의 생리학적 환경을 재현하기 위해 모의 생물학적 모형을 고안하였으며 이에 강선을 삽입하여 load cell (Push & pull gauge, RX-2 AIKOH, Osaka, Japan)로 분당 5 mm로 견인하며 만능시험기(Instron4467, Instron, Norwood, MA, USA)로 마찰저항을 측정하였다. 실험결과, 실험군인 인산칼슘 재질 브라켓의 마찰저항은 대조군인 금속슬롯 삽입형 도재 브라켓 보다 작고 (p < 0.01) 금속재 브라켓의 마찰저항보다 크게 나타나 (p < 0.05), 인산칼슘재 브라켓은 심미적 측면에서 금속재 브라켓을, 효율적 측면에서 금속슬롯 삽입형 도재 브라켓을 대체하여 사용 가능함을 시사하였다.

• Journal of Electrical Engineering and Technology
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• 제6권1호
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• pp.123-127
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• 2011

To clarify the relations of optical properties to the main factors responsible for the loss and damage of luminous efficacy, a 20 min turn-on/turn-off test for 2,000 h for a ceramic metal halide lamp is conducted. The corrosion rates of the arc tube wall and electrode are estimated based on thermal stress. Wall blackening is attributed to the tungsten being transported from the hot electrode tips to the relatively cold arc tube wall. Furthermore, the grain boundaries of the arc tube are changed by the degradation. Distortion of the electrode is observed, and the ignition and the driving voltage of the load both increase. Finally, the color rendering index and the color coordinates are changed after the degradation. The luminous flux and the intensity of the luminous distribution are decreased significantly.

• 산업기술연구
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• 제31권B호
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• pp.67-73
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• 2011

Ceramic metal halide lamps have been widely used due to long lifetime, high luminous efficiency and good colour rendering. In this paper, we developed dimming control system of electronic ballast for 70W ceramic metal halide lamp by using 1-10V interface. The proposed electronic ballast is consists of EMI filter, Full-wave rectifier, Active PFC, DBI(Dual Buck Inverter), Igniter and control circuit.It enables to supply both low-frequency rectangular wave voltage and current to the lamp by using DBI(Dual Bcuk Inverter) structure. By using 1-10V interface, the system that able to dimming the lamp is demonstrated by P-spice simulation and experimental results.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1989년도 하계종합학술대회 논문집
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• pp.333-334
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• 1989

Electrically active part of the piezoelectric sound element is a ceramic thin circular disk cemented to a metal base plate (using a type of thermosetting epoxy). The active part is a thin lead zirconate titanate disk (PZT). The piezoelectric sound element is so dimensioned that its basic resonance frequency is approximately if the center of the audible frequency band: This frequency is mainly determined by the geometry and the sort of the metal base plate materials. In this study, four kinds of PZT ceramic and two classes of thin metal base plate were prepared. It is observed that dielectric and pizoelectric properties relate to acoustical properties (particularly sound pressure level).

• 대한치과보철학회지
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• 제35권2호
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• pp.265-276
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• 1997

The effect of thermocycling and surface finishing on the marginal fidelity of copings for a metal ceramic crown was examined. Methods for minimizing the loss of marginal fidelity were evaluated. The results were as follows ; 1. Thermocycling of ceramic metal copings resulted in increased marginal gap. 2. The greatest marginal gap occurred during the first thermocycling of the copings. 3. No additional distortion of marginal fidelity occurred when surface finishing and second thermocycling were completed after initial thermocycling. 4. The gap increases according to various treatment methods showed group 1 to be the highest values. 5. There was no significant difference between group 2 and group 3(p>0.05) 6. There was significant difference between group 1 and group 2, 3(p<0.05). 7. There was no significant difference among the measurement sites.

• 산업기술연구
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• 제30권A호
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• pp.75-81
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• 2010

We described the operating principles of two different type of igniters for lightning of Ceramic Metal Halide Lamp(CMHL) and also provide some useful comparisons. One is for magnetic ballast, the other one is for electronic ballast which operates lamp by low-frequency square-waveform. Ignition voltage of lamp depends on the structure of igniter, such as the length and electrical characteristics of cable, which make troubles for ignition in real sites. Therefore, we measured and analyzed ignition voltages from igniters which are used in magnetic and electronic ballast in cables at a distance of 5 meters between a lamp and a igniter to suggests an applicable solution in real sites.

• 전기학회논문지
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• 제58권10호
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• pp.1947-1953
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• 2009

Metal halide (MH) lamps have been largely used due to high luminous efficiency, good color rendering, and long life. Since the metal halide lamps have problems of high ignition voltage and acoustic resonance. Thus, the design of ballast is very difficult for engineers. This paper proposes prototype of electric ballast in order to solve above two problems. The proposed electric ballast is consisted of EMI filter, full wave rectifier circuit, active PFC, DBI(Dual Buck Inverter), dimming circuit and ignitor circuit. The DBI supplies both rectangular voltage and current to the lamp. As the result of the experiment, the acoustic resonance was eliminated and the ignitor circuit was designed to generate high ignition voltage than 5kV. It makes the dimming circuit possible to control the lamp power in range between 230W and 350W.