• Korean Journal of Materials Research
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• v.33 no.10
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• pp.414-421
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• 2023

Infrared radiation (IR) refers to the region of the electromagnetic radiation spectrum where wavelengths range from about 700 nm to 1 mm. Any object with a temperature above absolute zero (0 K) radiates in the infrared region, and a material that transmits radiant energy in the range of 0.74 to 1.4 um is referred to as a near-infrared optical material. Germanate-based glass is attracting attention as a glass material for infrared optical lenses because of its simple manufacturing process. With the recent development of the glass molding press (GMP) process, thermal imaging cameras using oxide-based infrared lenses can be easily mass-produced, expanding their uses. To improve the mechanical and optical properties of commercial materials consisting of ternary systems, germanate-based heavy metal oxide glasses were prepared using a melt-cooling method. The fabricated samples were evaluated for thermal, structural, and optical properties using DSC, XRD, and XRF, respectively. To derive a composition with high glass stability for lens applications, ZnO and Sb₂O₃ were substituted at 0, 1, 2, 3, and 4 mol%. The glass with 1 mol% added Sb₂O₃ was confirmed to have the optimal conditions, with an optical transmittance of 80 % or more, a glass transition temperature of 660 ℃, a refractive index of 1.810, and a Vickers hardness of 558. The possibility of its application as an alternative infrared lens material to existing commercial materials capable of GMP processing was confirmed.

• Journal of the Korean Vacuum Society
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• v.4 no.2
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• pp.124-134
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• 1995

포항가속기연구소에서는 PLS 2-GeV 선형가속기 클라이스트론의 교체 및 보수시에 사용하기 위하여, 80 MW급 S-band의 도파관 밸브를 개발중에 있다. PLS형 도파관 밸브는 결합수단 없이 대전력을 전송할 수 있는 구조로 설계되어, 전력전송에 대한 제한을 받지 않는 특징을 갖는다. 본 도파관 밸브의 주요구성부는 밀착구동체를 갖는 U자형 도파관부, 두 개의 H-코너가 부착된 진공함, 그리고 두 개의 Viton O-링이 장착된 진공기밀판으로 이루어져 있다. 시제품용 도파관 밸브의 특성조사 결과, 펄스폭 3.5 $\mu$sec, 반복율 30 Hz에서 65MW의 전력전송을 얻을 수 있었다. 본 논문에서는 PLS도파관 밸브의 설계 개념, 기계적 특성 및 가공의 순으로 자세히 논할 것이며, 또한 현재까지의 실험결과 및 앞으로의 계획에 대하여 보고하기로 한다.

• Proceedings of the Optical Society of Korea Conference
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• 2000.02a
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• pp.70-71
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• 2000

Ge이 도핑된 실리카 광도파로 코어는 GeO$_2$분자의 산소결핍에 의하여 248nm의 파장을 갖는 자외선에 대해서 광감응성을 가지게 된다. 따라서 248nm 파장의 레이저를 간섭시켜 조사할 경우, Ge가 도핑되지 않은 overcladding 부분은 투과하고 간섭 패턴의 에너지 분포에 따라 코어의 굴절률이 주기적으로 변화한다. 이 주기적인 굴절률 변화는 잘 알려진 광학적 브래그 격자(Bragg grating)의 역할을 하게된다. 자외선 레이저를 이용하여 영구적인 굴절률 변화를 코어 내부에 형성시키는 방법으로는 홀로그램법과 위상 마스크를 이용하는 방법, 그리고 단일 슬릿을 이용하는 방법등이 있다[1][2]. (중략)

• Proceedings of the KSME Conference
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• 2004.04a
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• pp.2111-2116
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• 2004

This paper shows how to improve the efficiency and output and to reduce NOx emission of Seoinchon GE 7F gas turbine, Korea Western Power Co. by replacing the existing 7F gas turbine with new 7FA+e gas turbine because the performance of 7F gas turbine was degraded due to long term operation. In this paper, we will study gas turbine development trend and O&M technology. Finally, we will review for uprate of Seoinchon 7F gas turbine to help someone to improve their units in the future.

• Proceedings of the Korean Vacuum Society Conference
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• 2010.02a
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• pp.369-369
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• 2010

Adsorption and ordering of methionine molecules on Ge(100) surface have been studied using high resolution photoemission spectroscopy and low-energy electron diffraction (LEED) to investigate the adsorption structure as a function of coverage. Analysis of C 1s, S 2p, N 1s, and O 1s core levels reveals quite different according to methionine coverage. We found that the relative population of the two types of thiolates induces a structural change in the ordering from $2\;{\times}\;1$ to $1\;{\times}\;1$. Such an unusual evolution of the methionine adsorption on the Ge(100) surface is discussed in relation to chemical reactions and possible molecular rearrangement on the surface.

• 한국정보디스플레이학회:학술대회논문집
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• 2007.08b
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• pp.1526-1528
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• 2007

In this report, Manganese doped magnesium germanate ($Mg_4GeO_2:Mn$) phosphor has been synthesized by the solid state method. Also, this phosphor was prepared by simple process under an air atmosphere for oxidation of Mn. The prepared phosphor shows a main luminescent peak at 661nm. Therefore, this phosphor is possible to be applicable to white LED lamp by GaN or InGaN chips.

• Journal of the Korean Ceramic Society
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• v.37 no.6
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• pp.524-529
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• 2000

Silica slab wavegudie was fabricated on Si substrates by FHD for planar optical passive devices. The slab waveguide consists of lower clad and core layers, where core layer index is controlled by GeO2 addition. Doping of GeO2 in silica is difficult because of the low deposition density due to nonspherical particle generation in FHD process. Silica core particles deposited at various conditions such as flame temperature and substrate scanning were analyzed by SEM and TEM. As the flame temperature increased, the surface roughness of the core layer was decreased up to 3.6 nm after consolidation. Index difference and thickness of core of slab waveguide were 0.3%, 8$\mu\textrm{m}$ respectively. Measured optical loss at TE mode was <0.04 dB/cm at 1.3$\mu\textrm{m}$ and <0.06 dB/cm at 1.55$\mu\textrm{m}$.

• Korean Journal of Optics and Photonics
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• v.5 no.2
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• pp.304-310
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• 1994

The use of thermally expanded core (TEe) fibers fabricated by thermal diffusion of dopants such as $GeO_{2}$ in hybrid fiber components has an advantage of eliminating lenses for collimation and focusing. An electric furnace is fabricated to heat the fibers locally for the core expansion. We observed an expansion of the mode size at $1.3\mu\textrm{m}$ wavelength by 27% after treating a section of single mode optical fiber at $1250^{\circ}C$ for 10 hours. hours.

• Korean Journal of Materials Research
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• v.27 no.6
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• pp.312-317
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• 2017

In the construction of a white LED, the region of the red emission is a very important factor. Red light emitting materials play an important role in improving the color rendering index of commercial lighting. These materials also increase the color gamut of display products. Therefore, the development of novel phosphors with red emission and the study of color tuning are actively underway to improve product quality. In the present study, heuristic algorithms were used to search for phosphors capable of increasing the color rendering index and color gamut. Using a heuristic algorithm, the phosphors that were identified were $SrGe_4O_9:Mn^{4+}$ and $BaGe_4O_9:Mn^{4+}$. Emission spectra study confirmed that these phosphors emit light in the deep red wavelength region, which can fulfill the requirement for the improvement in color rendering index and color gamut for a white LED.

• JSTS:Journal of Semiconductor Technology and Science
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• v.7 no.4
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• pp.281-286
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• 2007

In this paper, sub-circuits for 24 GHz phase locked 100ps(PLLs) using $0.5{\mu}m$ SiGe HBT are presented. They are 24 Ghz voltage controlled oscillator(VCO), 24 GHz to 12 GHz regenerative frequency divider(RFD) and 12 GHz to 1.5 GHz static frequency divider. $0.5{\mu}m$ SiGe HBT technology, which offers transistors with 90 GHz fMAX and 3 aluminum metal layers, is employed. The 24 GHz VCO employed series feedback topology for high frequency operation and showed -1.8 to -3.8 dBm output power within tuning range from 23.2 GHz to 26 GHz. The 24 GHz to 12 GHz RFD, based on Gilbert cell mixer, showed 1.2 GHz bandwidth around 24 GHz under 2 dBm input and consumes 44 mA from 3 V power supply including I/O buffers for measurement. ECL based static divider operated up to 12.5 GHz while generating divide by 8 output frequency. The static divider drains 22 mA from 3 V power supply.