• Journal of the Semiconductor & Display Technology
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• v.11 no.4
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• pp.19-23
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• 2012

We report microbolometer characteristic with n-type and p-type amorphous silicon thin film. The n-type and p-type amorphous silicon thin films were made by PECVD. The electrical properties of n-type and p-type a-Si:H thin films were investigated as a function of doping gas flow rate. The doping gas used $B_2H_6/Ar$ (1:9) and $PH_3/Ar$ (1:9). In general, the conductivity of doping a-Si:H thin films increased as doping gas increase but the conductivity of a-Si:H thin films decreased as the doping gas increase because doping gas concentration increase led to dilution gas (Ar) increase as the same time. We fabricated an amorphous silicon microbolometer using surface micromachining technology. The fabricated microbolometer had a negative TCR of 2.3%. The p-type microbolometer had responsivity of $5{\times}10^4V/W$ and high detectivity of $3{\times}10^8cm(Hz)^{1/2}/W$. The p-type microbolometer had more detectivity than n-type for less noise value.

• Electronics and Telecommunications Trends
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• v.16 no.1 s.67
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• pp.56-70
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• 2001

마이크로파대 이상의 높은 RF 전파는 신호레벨이 비교적 작고 간섭현상에 매우 민감한 특성을 가지고 있다. 따라서 이러한 미소한 입력전파의 수신시 수신기 전체의 감도를 높이고 잡음을 저감시킬 목적으로 사용되는 고주파 증폭기가 저잡음 증폭기이다. 본 고에서는 LNA의 기본적 특성분석과 지능형교통시스템에 응용되는 5.8GHz대 단거리전용통신용 LNA를 구현하기 위한 기본 FET 증폭기의 전기적 특성을 연구하고 직렬 궤환에 의한 최소잡음과 최소 입력 정재파비의 최적 설계 파라미터를 도출하였다.

• Journal of Korean Ophthalmic Optics Society
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• v.8 no.1
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• pp.11-15
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• 2003

Purpose : The purpose of this study is to investigate the corneal topography changes as a result of near task in myopes and emmetropes. Methods : Thirty university students, aged from 18 to 24 years old, were randomly selected. They were divided into two refractive groups of fifteen each : myopia and emmetropia. The corneal topography of each subject was measured with the Eye-Sys Videokeratography system. Measurements were taken : before and after 30 minutes of near task (copy N10 text at 20 cm working distance). Both simulated keratometry and semi-meridian keratometric map program were used in the data analysis. Results : Our results reveal no significant changes in both simulated keratometry and semi-meridian presentation as a result of near task for both myopes and emmetropes, except a significant change (p<0.05) found at the flattest meridian of the central (3 mm) portion of the corneal topography after near task for emmetropes only. Conclusions : We conclude that the corneal topography, does not change significantly as a result of near task in both myopes and emmetropes.

• Clean Technology
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• v.27 no.1
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• pp.47-54
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• 2021

The adsorption of Acid Fuchsin (AF) on granular activated carbon (GAC) was investigated for isothermal adsorption and kinetics and thermodynamic parameters by experimenting with the initial concentration, contact time, temperature, and pH of the dye as adsorption parameters. In the pH effect experiment, the adsorption of AF on activated carbon showed a bathtub type with increased adsorption at pH 3 and 11. The adsorption equilibrium data of AF fit well with the Freundlich isotherm model, and the calculated separation factor (1/n) value was found in which activated carbon can effectively remove AF. The pseudo-second-order kinetic model fits well within 7.88% of the error percent in the adsorption process. According to Weber and Morris's model plot, it was divided into two straight lines. The intraparticle diffusion rate was slow because the stage 2 (intraparticle diffusion) slope was smaller than that of stage 1 (boundary layer diffusion). Therefore, it was confirmed that the intraparticle diffusion was a rate-controlling step. The activation energy of AF (13.00 kJ mol-1) corresponded to the physical adsorption process (5 - 40 kJ mol-1). The free energy change of the AF adsorption by activated carbon showed negative values at 298-318 K. As the spontaneity increased with increasing temperature. The adsorption of AF was an endothermic reaction (ΔH = 22.65 kJ mol-1).

• Journal of the Korean Chemical Society
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• v.31 no.3
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• pp.207-214
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• 1987

Rates of solvblysis of benzyl chloride in ethanol-water mixtures have been measured at 30 and $40^{\circ}C$ under various pressures up 1.6 kbar. The plots of 1n k as a function of pressure are fitted to a second order function in p, and values of ${\Delta}V^{\neq}$and ${\Delta}{\beta}^{\neq}$ are obtained from the results. Also the values of various pseudo thermodynamic quantities were evaluated from the rate constants. The relationships of the 1n k to $Q_w$ or 1n $C_w$ indicate that the reaction proceeds through $S_N1$ mechanism. A comparison between the present and the previous results gives that the increasing order of ${\mid}{{\Delta}V_0}^{\neq}{\mid}$ and n-values are $p-Cl>p-H>p-CH_3$ and $p-CH_3>p-H.p-Cl$, respectively. From these results, it is believed substituent such as the $p-CH_3$group favors the $S_N1(1)$ character, while the p-Cl group leads to the $S_N1(2)$ character.

• Journal of the Korean Society for Nondestructive Testing
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• v.22 no.4
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• pp.347-353
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• 2002

A structure of a glass electrode-type pH sensor for measuring any concentration of $H^+$ in an aqueous solution was embodied with bulk micromachining technology. Two open well structures were formed, and a reference electrode was secured by the Ag/AgCl thin film in the sloped side of the etched structure. A sensitive membrane of an indicator electrode for generating a potential by an exchange reaction to $H^+$ was made with a glass containing Na 20% or more finely so that its thickness might be $100{\mu}m$ or so, and then it was bonded to one pyramidal structure. A liquid junction for a current path was formed by filling an agar in the anisotropically etched part of the Si wafer, which had a size of $50{\mu}m{\times}50{\mu}m$, and then bonded it to the other. After complete fabrication of each part, it was filled with a 2M KCl reference solution and encapsulated the sensor structure with a cold expoxy. The potential value of fabricated pH sensor was about 90mV/pH in the standard pH solutions.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.1
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• pp.739-744
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• 2020

This study evaluates the erosive potential and effects of mixed alcohols by analyzing the pH, titratable acidity, and fluorescence loss degree (△F). Following alcohol groups were investigated: Soju, Calamansi+soju, Yakult+soju, Cola+soju, and Energy drink+soju. The ratio of soju:beverage in the alcohol mixtures was 7:3. Ed. Notes: The sentence lacks clarity. Please review if the edit correctly portrays the meaning. If not, please revise appropriately. Measurement of the pH and titratable acidity (the amount of 1M NaoH solution required to raise to pH 5.5 (TA5.5) and 7.0 (TA7.0)) of alcohols was achieved by stirring with pH meter. The erosive effect of the alcohol mixtures on bovine tooth (△F) after 1, 2, 4, and 6 hours exposure were analyzed by quantitative light-induced fluorescence (QLF-D). All the mixed alcohols in this study showed an acidic pH, lower than 4.5. The average pH of mixed alcohols was 3.17 ± 0.50 whereas the pH of Soju was 8.6 ± 0.01. The TA5.5 and TA7.0 values of the mixed alcohols were 0.5~18 and 0.5~23.5, respectively. △F of the three tested mixed alcohol groups (except yakult+soju group) were observed to increase in a time-dependent manner. The calamansi mixed alcohol had the highest acidity potential and erosive effect among the tested groups. Taken together, the results indicate that the mixed alcohols have a strong erosive effect and potential on dental enamel.

• The Korean Journal of Pesticide Science
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• v.7 no.1
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• pp.58-65
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• 2003

Various physicochemical parameters for the active ingredients of 245 herbicides were calculated to develope a diagnosis and estimation system for utility as herbicide. The range of physico-chemical parameters for each inhibitors of photo system II (H1), acetolactate synthase (ALS) (H2) and herbicides were confirmed. The distribution ranges of 85% dependence for each physicochemical parameters were Obs.logP :$-0.90\sim4.50$, dipol moment: $1.80\sim12.22$ (debye), molecular refractivity: $53.0\sim104.0(cm^3/mol)$, polarizability: $19.0\sim37.0(\AA^3)$, HOMO energy: $-9.98\sim-7.34$ (eV), LUMO energy:$-2.76\sim0.40$ (eV), Van der Waals molecular volumes: $558.0\sim995.0(cm^3)$, molecular weight: $202.0\sim430.0$ (amu) and surface areas (Grids): $194.0\sim356.0(\AA^2)$, hydration energy: $-10.16\sim114.7$ Kcal/mol, respectively. It is suggested that MR and polarizability constants will be able to distinguish between herbicides and medicinal drugs. Results revealed that various compounds based on the range of physicochemical parameters of herbicides could be diagnosed and estimated.

• Clean Technology
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• v.26 no.3
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• pp.186-195
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• 2020

The isothermal adsorption, dynamic, and thermodynamic parameters of Acid black (AB) and Quinoline yellow (QY) adsorption by activated carbon were investigated using the initial concentration, contact time, temperature, and pH of the dyes as adsorption parameters. The adsorption equilibrium data fits the Freundlich isothermal adsorption model, and the calculated Freundlich separation factor values found that activated carbon can effectively remove AB and QY. Comparing the kinetic data showed that the pseudo second order model was within 10% error in the adsorption process. The intraparticle diffusion equation results were divided into two straight lines. Since the slope of the intraparticle diffusion line was smaller than the slope of the boundary layer diffusion line, it was confirmed that intraparticle diffusion was the rate-controlling step. The thermodynamic experiments indicated that the activation energies of AB and QY were 19.87 kJ mol^-1 and 14.17 kJ mol^-1, which corresponded with the physical adsorption process (5 ~ 40 kJ mol^-1). The adsorption reaction was spontaneous because the free energy change in the adsorption of AB and QY by activated carbon was negative from 298 to 318 K. As the temperature increased, the free energy value decreased resulting in higher spontaneity. Adsorption of AB and QY by activated carbon showed the highest adsorption removal rate at pH 3 due to the effect of anions generated by dissociation. The adsorption mechanism was electrostatic attraction.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.7
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• pp.667-674
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• 2020

The adsorption of reactive orange 16 (RO 16) dye by activated carbon was investigated using the amount of adsorbent, pH, initial concentration, contact time and temperature as adsorption variables. The investigated process parameters were separation coefficient, rate constant, rate controlling step, activation energy, enthalpy, entropy, and free energy. The adsorption of RO 16 was the highest at pH 3 due to the electrostatic attraction between the cations (H⁺) on the surface of the activated carbon and the sulfonate ions and hydroxy ions possessed by RO 16. Isotherm data were fitted into Langmuir, Freundlich and Temkin isotherm models by applying the evaluated separation factor of Langmuir (RL=0.459~0.491) and Freundlich (1/n=0.398~0.441). Therefore, the adsorption operation of RO 16 by activated carbon was confirmed as an appropriate removal method. Temkin's adsorption energy indicated that this adsorption process was physical adsorption. The adsorption kinetics studies showed that the adsorption of RO 16 follows the pseudo-second-order kinetic model and that the rate controlling step in the adsorption process was the intraparticle diffusion step. The positive enthalpy change indicated an endothermic process. The negative Gibbs free energy change decreased in the order of -3.16 <-11.60 <-14.01 kJ/mol as the temperature increased. Therefore, it was shown that the spontaneity of the adsorption process of RO 16 increases with increasing temperature.