• Journal of IKEEE
• /
• v.12 no.3
• /
• pp.131-137
• /
• 2008

A silicon Fabry-Perot tunable thermo-optic filter for WDM using the thin film silicon coating is proposed and experimented. The filter is implemented by using the CMP process and polishing both sides of the commercial silicon wafer with normal thickness of 100${\mu}m{\pm}$1%. The filter also has 2-layer or 3-layer dielectrics thin film coating mirror which are alternated ${\lambda}$/4 layers of $SiO_2$($n_{low}$=1.44) and a-Si($n_{high}$=3.48) for the central wavelength of 1550nm by RF sputtering. The experiment shows that FSR is 3.61nm and FWHM is 0.56nm and the finesse is 6.4 for 2-layer mirror with the reflection of 61%, and that FSR is 3.36nm and FWHM is 0.13nm and the finesse is 25.5 for 3-layer mirror with the reflection of 89%. According to thermo-optic effect, the transmitted central wavelength of 1549.73nm at $23^{\circ}C$ is shifted to 1550.91nm at $30^{\circ}C$ and 1553.46nm at $60^{\circ}C$ for 2-layer mirror, and the transmitted central wavelength of 1549.83nm at $23^{\circ}C$ is shifted to 1550.92nm at $30^{\circ}C$ and 1553.07nm at $60^{\circ}C$ for 3-layer mirror.

• Journal of the Korean Ceramic Society
• /
• v.36 no.3
• /
• pp.274-283
• /
• 1999

1.1-nm tobermorite의 수열합성에 SiO2원으로 zeolite광물을 출발물질로하여 소석회와 Ca(Si+Al)의 몰비 0.8~1.0로 150$^{\circ}$~23$0^{\circ}C$,8~48시간 동ㅇㄴ 포화증기압하에서 수열반응을 시킨 결과, 반응초기단계에서 tobermorite가 생성되었고, 고결정성 1.1-nm tobermorite의 최적합성조건은 0.8몰, 23$0^{\circ}C$, 48시간이었다. 출발물질중 Al의 존재로 tobermorite는 Ca/(Si+Al)몰비 0.8이 1.0보다 결정화가 급속히 이루어지고 있으나 Al를 함유치 않은 석영의 경우에는 Ca/Si 몰비 1.0이 0.8에서 보다 결정화가 빠르게 진행되었다 1.1-nm tobermorite는 $700^{\circ}C$에서 일주일간 가열처리하여도 저면간격이 변화하지 않는 열적거동이 이상형임을 보여주었다. 특히 출발물질중 Al의 존재는 1.1-nm tobermorite의 결정화와 안정화를 촉진시켜주며 Al이온이 tobermorite구조중의 Si이온과 동형치환을 한다.

• Journal of the Microelectronics and Packaging Society
• /
• v.23 no.4
• /
• pp.25-29
• /
• 2016

The semiconductor industry has been developed mainly by micronization process due to many advantages of miniaturization of devices. Mass production of semiconductors of 10 nm class has been started recently, and it is expected that the technology generation of 5 nm & 7 nm technology will come. However, excessive linewidth reduction affects physical limits and device reliability. To solve these problems, new process technology development and new concept devices are being studied. In this review, we introduce the next generation technology and introduce the advanced research for the new concept device.

• Journal of the Korean Association of Geographic Information Studies
• /
• v.3 no.3
• /
• pp.12-19
• /
• 2000

Knowledge for reflectance characteristic of interesting targets will provide us with actual application of remote sensing on agriculture. In this study, we have measured and analyzed reflectivity characteristics based on growing status from transplanting time to harvesting time. Rice paddies transplant into 3 fields at 20, May, 1999. Measurement of reflectivity characteristics were carried out with a portable spectroradiometer for frequencies from 300nm to 1100nm during the time period from 11:00 AM to 01:00 PM of clear sky and calm a day. The measurements for a day repeated 3 times(also, 3 times to each measurement)for reliable values. In result, we found that averaged reflectivity of visible range has about 2.34% - 2.55% in blue region(400nm-498nm), about 5.05% - 6.01% in green region(500nm-598nm) and about 4.21% - 5.24% in red region(600nm-698nm). It must be noted that the more rice canopy grows, the more spectral reflectivity decreases in visible region. Also, we separated infrared region into two cases - One case is increasing region with 700nm-780nm, the other is fixed region with 800nm-1100nm. Averaged reflectivity of these regions has about 22.3% - 23.0% in increasing region, about 29.4% - 33.1% in fixed region. It must be noted that more rice canopy grows, the more spectral reflectivity also increases up to 23, Aug. in infrared region. After 23, Aug, the reflectivity has a tendency toward decrease.

• The Korean Journal of Mycology
• /
• v.20 no.2
• /
• pp.149-153
• /
• 1992

This study aimed to investigate possible cause of slow and abnormal growth of oyster mushrooms, Pleurotus florida and P. ostreatus collected from bad crop farms. Spherical virus particles of 30 nm in diameter from P. florida, 23 nm particles from P. ostreatus, and both 23 and 30 nm particles were also found from interspecies mated culture between P. florida and P. osreatus. The virus particles might be associated with the bad crop of Pleurotus species.

• Journal of IKEEE
• /
• v.23 no.3
• /
• pp.865-872
• /
• 2019

We developed a one-dimensional Ar fluid model running in DC-type applied voltage with a sine and a pulse waveform at the atmosphere pressure. We investigated the light emissions and efficiencies of ${\lambda}_{128nm}$, ${\lambda}_{727nm}$, ${\lambda}_{912nm}$ and ${\lambda}_{966nm}$ from the Ar excited particles. From the results, the light emission of ${\lambda}_{128nm}$ and ${\lambda}_{727nm}$ in the applied voltage with a sine waveform were almost two times as in DC voltage type. The shorter the switching time of applied voltage was, the more the light emissions of ${\lambda}_{128nm}$ and ${\lambda}_{727nm}$ were. We discussed the power consumption and Joule heating by charged particles.

• Bulletin of the Korean Chemical Society
• /
• v.23 no.2
• /
• pp.286-290
• /
• 2002

Hydrogen atom production channels from photodissociation of benzene, phenylacetylene, and benzaldehyde at 243 nm have been investigated by detecting H atoms using two photon absorption at 243.2 nm and induced fluorescence at 121.6 nm. Translational energies of the H atoms were measured by Doppler broadened H atom spectra. By absorption of two photons at 243 nm, the H atoms are statistically produced from benzene and phenylacetylene whereas the H atoms from the aldehyde group in benzaldehyde are produced from different pathways. The possible dissociation mechanisms are discussed from the measured translational energy releases.

• Bulletin of the Korean Chemical Society
• /
• v.23 no.2
• /
• pp.179-183
• /
• 2002

Resonance-enhanced multiphoton ionization with time-of-flight product imaging of the $N(^2D)$ atoms has been used to study the $N_2O$ photodissociation at 118.2 nm and the two-photon dissociation at 268.9 nm. These imaging experiments allowed the determination of the total kinetic energy distribution of the $NO(X^2{\prod})$ and $N(^2D_{5/2})$ products. The $NO(X^2{\prod})$ fragments resulting from the photodissociation processes are produced in highly vibrationally excited states. The two-photon photodissociation process yields a broad $NO(X^2{\prod})$ vibrational energy distribution, while the 118.2 nm dissociation appears to produce a vibrational distribution sharply peaked at $NO(X^2{\prod},\;{\nu}=14)$.

• Bulletin of the Korean Chemical Society
• /
• v.21 no.4
• /
• pp.383-388
• /
• 2000

Multiblock copolymers consisting of poly( g-benzyl L-glutamate) (PBLG) as the hydrophobic part and poly(ethylene oxide) (PEO) as the hydrophilic part (GEG) were synthesized and characterized. GEG polymeric micelles were prepared by the dialysis technique. Particle size distributions based on intensity,volume, and number-average were 22.6 $\pm$ 11.9 nm, 23.5 $\pm$ 4.6 nm, and 23.7 $\pm$ 37 nm, respectively. It was observed that par-ticle size and size distribution of GEG polymeric micelles changed significantly with the choice of initial sol-vent. Transmission electron micrographs (TEM) showed the polymeric micelles to be spherically shaped, with sizes ranging from 20 nm to 40 nm in diameter. Fluorescence spectroscopy measurements suggested that GEG block copolymers wereassociated in water to form polymeric micelles, and the critical micelle concentrations (CMC) value of the block copolymers was 0.0094 g/L. Further evidenceof micelle formation of GEG block copolymers and limited mobility of the PBLG chain in the core ohe micelle was obtained with 1 H NMR in D2O.

• Korean Journal of Optics and Photonics
• /
• v.23 no.3
• /
• pp.108-112
• /
• 2012

In this paper, two wavelengths mainly used for laser prostatectomy have been quantitatively compared: 532 and 980 nm. Two lasers at 40 W were employed to ablate bovine liver in vitro. Ablation performance was evaluated in light of number of sweeps, ablation volume, and coagulative necrosis. 532 nm yielded up to four times higher ablation efficiency than 980 nm. Regardless of wavelength, ablation rate per sweep decreased with the number of sweeps. 532 nm generated relatively deeper ablation craters along with thinner coagulation whereas 980 nm created superficial tissue ablation with up to 2 mm thick coagulative necrosis. Due to higher light absorption and effective thermal confinement, 532 nm induced more efficient tissue ablation with a smaller coagulative necrotic zone. The current study demonstrated that 532 nm could be a more ideal wavelength for laser prostatectomy, and the future in vivo investigations will confirm these findings.