• Bulletin of the Korean Chemical Society
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• v.29 no.2
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• pp.393-397
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• 2008

Inductively coupled plasma atomic emission spectrometry (ICP-AES) was used to determine the presence of germanium and phosphorus in a pure gold bonding wire. The samples were dissolved with hydrobromic acid and nitric acid at room temperature. The quantitation limits were 0.012 mg L-1 at 265.118 nm for Ge and 0.009 mg L-1 at 177.495 nm for P. Using the mixed acid digestion formula of DIW+HBr+HNO3, the recoveries were in the range of 98-100% and the relative standard deviation was within 1.1-2.3%. On the other hand, the amount of Ge decreased by about 16.2% using DIW+HCl+HNO3, due to the formation of a volatile compound. The Ge contents determined using the external method and the standard addition method were 9.45 mg kg-1 and 9.24 mg kg-1, respectively, and the P contents, using the same methods, were 22.49 mg kg-1 and 23.09 mg kg-1, respectively. Both methods were successfully used to determine the trace amounts of P and Ge in the pure gold bonding wire samples.

• Analytical Science and Technology
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• v.25 no.3
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• pp.190-196
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• 2012

The human exposure of lead has usually detected the amount of lead in the whole blood, however, this method has a shortcoming to give the information on the short-term exposure to lead. In that sense, it is desirable to estimates the level of lead in plasma to draw the chronic bio-marker of lead exposure even though it is difficult to measure lead of several ng/L. An inductively coupled plasma-mass spectrometry (ICP-MS) method was developed for determining lead in plasma as the chronic bio-marker of lead of workers. To minimize the contamination of lead from the environment, we constructed class 1,000 clean room and compared the amount of floating dust before and after the operation of the clean room. The limit of detection (LOD) and the limit of quantification (LOQ) of lead in fetal bovine serum were 4.3 ng/L and 12.2 ng/L by NIOSH method (statistical calculation method) and 7.0 ng/L and 22.1 ng/L by signal/noise ratio, respectively. The accuracy was in a range of 92.3-101.3%, and the precision of the assay was less than 4% in the samples spiked in the concentration of 20 ng/L and 2,000 ng/L. The method was simple, reproducible and sensitive enough to permit reliable analysis of lead to the ng/L level in plasma and/or serum. The method was also useful for the biological monitoring of chronic exposure to lead.

• Proceedings of the KIEE Conference
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• 1997.11a
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• pp.279-281
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• 1997

The properties of Platinum dry etching were investigated in MICP(Magnetized Inductively Coupled Plasma). The problem with Platinum etching is the redeposition of sputtered Platinum on the sidewall. Because of the redeposits on the sidewall, the etching of patterned Platinum structure produce feature sizes that exceed the original dimension of the PR size and the etch profile has needle-like shape.[1] Generally, $Cl_2$ plasma is used for the fence-free etching.[1][2][3] The main object of this study was to investigate a new process technology for the fence-free Pt etching. Platinum was etched with Ar plasma at the cryogenic temperature and with Ar/$SF_6$ plasma at room temperature. In cryogenic etching, the height of fence was reduced to 20% at $-190^{\circ}C$ compared with that of room temp., but the etch profile was not fence-free. In Ar/$SF_6$ Plasma, chemical reaction took part in etching process. The trend of properties of Ar/$SF_6$ Plasma etching is similar to that of $Cl_2$ Plasma etching. Fence-free etching was possible, but PR selectivity was very low. A new gas chemistry for fence-free Platinum etching was proposed in this study.

• Proceedings of the KSME Conference
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• 2008.11a
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• pp.1028-1033
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• 2008

The mount type HVAC control system is a type of an HVAC control system which is installed between a ceiling and ceiling boards of a room to control room temperature. Although the device is quite popular, design is conducted by a conventional way where engineering intuition and experiences are utilized. It is found that the design process is fairly inefficient and time-consuming because there are a lot of feedbacks. The axiomatic approach is used to investigate the design characteristics of the mount type HAVC control system and the Independence Axiom is utilized for the investigation. The Overall hierarchy is established up to the level of parts. It is found that the current design has many coupled and redundant aspects. The hierarchy is reorganized based on the Independence Axiom and a new design process is found. To exploit the new design process in practice, a design manual is made.

• Proceedings of the Korean Vacuum Society Conference
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• 2014.02a
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• pp.297.2-297.2
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• 2014

Strong exciton-photon coupling in microcavities have generated an intense research effort since quasiparticles called exciton polaritons are produced and shows interesting phenomena. Most of studies have been done with GaAs based microcavities at cryogenic temperature. Recently, GaN material which has large exciton binding energy and oscillator strength has much attention because strong coupling between photon and exciton could be realized at room temperature. However, fabrication of high quality microcavity using GaN is challengeable due to the large mismatch between the lattice and the thermal expansion coefficient in GaN based distributed Bragg mirror. Here, we observed strong coupling regime of exciton-photon in GaN micro-rods which were grown by metalorganic vapour phase epitaxy (MOCVD) on Si substrate. Owing to the hexagonal cross-section of micro-rod, whispering gallery modes of photon are naturally formed and could be coupled with exciton in GaN. Using angle-resolved micro-photoluminescence measurement, exciton polariton dispersion curves were directly observed from GaN micro-rod. We expect room temperature exciton polariton condensation could be realized in high quality GaN micro-rod.

• The korean journal of orthodontics
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• v.49 no.1
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• pp.21-31
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• 2019

Objective: This study was performed to explore the effect of different bracket, archwire, and ligature combinations on resistance to sliding (RS) and rotational control in first-order angulation. Methods: Three types of brackets (multi-level low friction [MLF], self-ligating, and conventional brackets) coupled with four nickel-titanium archwires (0.012, 0.014, 0.016, and 0.018-inch diameter) and two stainless steel ligatures (0.20 and 0.25 mm) were tested in different first-order angulations ($0^{\circ}$, $2^{\circ}$, $4^{\circ}$, $6^{\circ}$, $8^{\circ}$, $10^{\circ}$, $15^{\circ}$, $20^{\circ}$) by using an Instron universal mechanical machine in the dry state at room temperature. RS value was evaluated and compared by one-way ANOVA. Results: Under the same angulation, the RS values showed the following order: conventional brackets > MLF brackets > self-ligating brackets. The RS was the highest for conventional brackets and showed a tendency to increase. The RS for MLF brackets coupled with thinner archwires and ligatures showed a similar tendency as the RS for the self-ligating bracket. In contrast, the RS for MLF brackets coupled with thicker archwires and ligatures increased like that for conventional brackets. MLF brackets showed the greatest range of critical contact angles in first-order angulation. Conclusions: The RS in first-order angulation is influenced by bracket design, archwire, and ligature dimension. In comparison with self-ligating and conventional brackets, MLF brackets could express low friction and rotational control with their greater range of critical contact angles.

• The Journal of the Acoustical Society of Korea
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• v.40 no.6
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• pp.626-648
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• 2021

Domestically, demands for multi-purpose performance venues which accommodate various performance genres have increased. However, those venues have limited capability and confined to a primary performance. The present work investigated various methods for controlling the acoustics of room for required performance genres by reviewing aurally presented and published materials. The method of varying the acoustics of a space is called Variable Acoustics, and adjusted in either passive and active ways. Passive control encompasses variable absorption, variable volume, coupled volume, and canopy reflectors, where the acoustics of a room is controlled in an architectural way. Active control includes In-line, Regenerative, and Hybrid systems where the acoustics of a room is manipulated electronically. The mechanism and application of each passive control system in existing venues are reviewed and their pros and cons are discussed. Also, the concept of each active systems and product applications are looked at through literature reviews. Lastly, some considerations that need to be taken into in the planning and design stage of a multi-purpose hall using Variable Acoustics are suggested.

• Proceedings of the KIEE Conference
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• 1999.07d
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• pp.1907-1909
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• 1999

In this paper, we report a high quality GaN films with high hole concentrations and low resistivities without post growth treatment using a GAIVBE system equipped with a home-made inductively coupled RF plasma source. The room temperature hole concentrations obtained were $5{\times}10^{17}{\sim}1.6{\times}10^{19}cm^{-3}$, and the mobilities were $2.5{\sim}8cm^2/Vs$. Also we have grown high quality n-type GaN films with the range of electron concentrations of $1.4{\times}10^{17}{\sim}4.7{\times}10^{19}cm^{-3}$ and the mobilities of $180{\sim}410cm^2/Vs$.

• Elastomers and Composites
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• v.32 no.5
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• pp.318-324
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• 1997

Since the rigid and continuous networks of high-purity silica(white carbon) were relatively transparent to microwaves, high purity silica coupled with microwaves using a zirconia susceptor at room temperature and it was then heated to its melting temperature. The low-purity silica, contained small amount of impurities, yielded greater microwave absorption owing to easy motion of the interstitial alkali ions and it was then heated to its melting temperature. X-ray diffraction patterns of the low-purity silica were broader than those of the high-purity silica due to higher concentration of non-bridging bond and more deformed random network structure. In the vulcanization process of whitened or coloured rubber compound which is employing low-purity silica(white carbon) as a reinforcing filler, vulcanizate could be obtained effectively by microwave heating energy.

• International Journal of Air-Conditioning and Refrigeration
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• v.15 no.3
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• pp.101-107
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• 2007

Indoor air quality becomes of a concern recently in view of human health. This study investigates the air diffusion performance and the air change efficiency of a classroom, when outdoor air is introduced in two different ways in addition to the heating/cooling operation of a ceiling-mounted heat pump. A CFD analysis has been performed to investigate the effect of the discharge angle of the air jets from the heat pump for both parallel and series types of outdoor air system. It is observed that the series type creates more uniform indoor environment compared to the parallel type in general. It can be concluded the discharge angle should not be larger than 40o for the parallel type, in order not to generate thermal stratification in the room.