• Applied Chemistry for Engineering
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• v.32 no.6
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• pp.640-646
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• 2021

In this study, pitch was synthesized using pyrolysis fuel oil (PFO). Coke with mesophase microstructure was then prepared from the synthesized pitch and its properties were evaluated. Pitch was synthesized by poly-condensation reaction, which is an endothermic reaction at a temperature above 400 ℃ because the PFO was mainly composed of molecules with two to three aromatic rings. The Coke reactor was composed of the pretreatment reactor, preheater for applying heat energy, and coke drum for inducing microstructure of coke. Coke was prepared from synthesized pitch by controlling the temperature of the preheater to 400~490 ℃, and properties were evaluated by polarization microscope, XRD and Raman spectroscopy. The coke prepared at a preheater temperature of 460 ℃ identified flow anisotropic microstructure, and the electrical conductivity was 72.0 S/cm due to high crystallinity. And the flow anisotropic coke showed approximately 2.2 times higher electrical conductivity than that of Super-P, a conductive carbon material.

• Korean Journal of Optics and Photonics
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• v.33 no.5
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• pp.201-209
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• 2022

The previously developed microspot spectroscopic ellipsometer (SE) is upgraded to a microspot SE compatible with the atomic force microscope (AFM). The focusing optical system of the previous microspot SE is optimized to incorporate an AFM head. In addition, the rotating compensator ellipsometer in polarizer-sample-compensator-analyzer configuration is adopted in order to minimize the negative effects caused by beam wobble. This research leads to the derivation of the expressions needed to get spectro-ellipsometric constants despite the fact that the employed rotating compensator is far from the ideal achromatic quarter-wave plate. The spot size of the developed microspot SE is less than 20 ㎛ while the AFM head is mounted. It operates in the wavelength range of 190-850 nm and has a measurement accuracy of δΔ ≤ 0.05° and δΨ ≤ 0.02°, respectively. Fast measurement of ≤3 s/sp is realized by precisely synchronizing the azimuthal angle of a rotating compensator with the spectrograph. The microspot SE integrated with an AFM is expected to be useful in characterizing the structure and optical properties of finely patterned samples.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.16 no.6
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• pp.413-419
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• 2023

Light Emitting Diodes(LEDs) are widely utilized not only in lighting but also in various applications such as mobile phones, automobiles, displays, etc. The integration of LED lighting with communication, specifically Visible Light Communication(VLC), has gained significant attention. This paper presents the direct implementation and experimentation of a Vehicle-to-Vehicle(V2V) Visible Light Communication system using commonly used red and yellow LEDs in typical vehicles. Data collected from the leading vehicle, including positional and speed information, were modulated using Non-Return-to-Zero On-Off Keying(NRZ-OOK) and transmitted through the rear lights equipped with red and yellow LEDs. A photodetector(PD) received the visible light signals, demodulated the data, and restored it. To mitigate the interference from fluorescent lights and natural light, a PD for interference removal was installed, and an interference removal device using a polarizing filter and a differential amplifier was employed. The performance of the proposed visible light communication system was analyzed in an ideal case, indoors and outdoors environments. In an outdoor setting, maintaining a distance of approximately 30[cm], and a transmission rate of 4800[bps] for inter-vehicle data transmission, the red LED exhibited a performance improvement of approximately 13.63[dB], while the yellow LED showed an improvement of about 11.9[dB].

• Korean Journal of Soil Science and Fertilizer
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• v.44 no.5
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• pp.916-921
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• 2011

This study was carry out on a Jang-Won series (fine loamy, mixed, mesic family of typic fragipan) that were established and classified as a fragipan soil in Korea. The morphological, physical, chemical and minerals characteristics of Jang-Won series were studied to determine the genesis of fragipan soils in natural environment. Each sample was analyzed for its physical, chemical and mineralogical characteristics. The particle size distribution of samples was measured using pipette method. Clay minerals were investigated on parallel-oriented specimens of the clay fraction ($<2{\mu}m$) from each horizon, separated by sieving and centrifugation, using X-ray diffraction (XRD) analysis. Micromorphological observations were made on thin sections prepared from soil blocks impregnated with Crystic Resin, cut and ground to less than $30{\mu}m$ in thickness, and finally polished with diamond paste. Most horizons have pH values in the range of fewer than 5.0 and have very low base-saturation values. Their textural classification ranges from silt loam to loam, the lower horizons being the finer. The clay fraction revealed the occurrence of illite, kaolinite, chlorite and vermiculite. The micro-morphological analysis carries out thin sections from each soil profile. The silt concentrations occur as extremely dense and homogenous bands or zones of silt-sized materials, brownish in colour in plane-polarized light and anisotropic in cross-polarized light, surrounding or adhering to skeleton grains. The genesis of fragipan in the Jangweon series assumed composition of clay fraction rather than silt concentration. Therefore, this results suggested an authentic interpretation which Jangweon series is classification as Typic Fragiochrepts.

• Journal of the Mineralogical Society of Korea
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• v.29 no.1
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• pp.23-34
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• 2016

Tsogttsetsii area, an intrusive complex associated with Cu porphyry mineralization, is located in the Gurvansaikhan island arc terrane of the Central Asian Orogenic belt, Southern Mongolia. We performed a reconnaissance survey in Tsogttsetsii area. Cu mineralization in Tsogttsetsii area is porphyry Cu type related with alkali granite intruded in Permian. Mineralogical and textural properties of the ores and associated minerals were analyzed using X-ray diffraction, thin section petrography, and Scanning electron microscopy-Energy dispersive spectroscopy (SEM-EDS). Ore minerals identified in polarizing microscope are magnetite, pyrite and bornite. Propylitic alteration zone occurs broadly in the area where malachite occurrences are shown to be spread intensively in alkali granite area. Quartz, sericite, chlorite and epidote were observed in the alteration zone samples. As results of XRD and SEM-EDS analysis, samples of copper oxides were composed mainly of malachite, cuprite and small amounts of quartz. Average and maximum Cu contents of samples collected from malachite occurrences area are 759 ppm and 6190 ppm, respectively. The characteristics of mineralization in Tsogttsetsii area is similar to Oyu Tolgoi Cu-Au (Mo) deposit and Tsagaan Suvarga Cu-Mo deposit which are 56 km south and 120 km northeast from Tsogttsetsii area, respectively. Characteristics of the study area, such as the geology, tectonic environment, lithology, mineralization, and alterations of the rocks within the survey area, resemble the characteristics of other porphyry deposits. Therefore further exploration including Induced Polarization (IP) survey for identifying subsurface orebody is required.

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.48 no.6
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• pp.18-26
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• 2011

Debates concerning the competitive edge of leading 3DTV technology of the shutter glasses (SG) 3D and the film-type patterned retarder (FPR) are flaring up. Although SG technology enables Full-HD 3D vision, it requires complex systems including the sync transmitter (emitter), the sync processor chip, and the LCD lens in the active shutter glasses. In addition, the transferred sync-signal is easily affected by the external noise and a 3DTV viewer may feel flicker-effect caused by cross-talk of the left and right image. The operating current of the sync processor in the 3DTV active shutter glasses is gradually increasing to compensate the sync reconstruction error. The proposed chip is a low-power hardware sync processor based discrete-event SoC(system on a chip) designed specifically for the 3DTV active shutter glasses. This processor implements the newly designed power-saving techniques targeted for low-power operation in a noisy environment between 3DTV and the active shutter glasses. This design includes a hardware pre-processor based on a universal edge tracer and provides a perfect sync reconstruction based on a floating-point timer to advance the prior commercial 3DTV shutter glasses in terms of their power consumption. These two techniques enable an accurate sync reconstruction in the slow clock frequency of the synchronization timer and reduce the power consumption to less than about a maximum of 20% compared with other major commercial processors. This article describes the system's architecture and the details of the proposed techniques, also identifying the key concepts and functions.

• Journal of the Korean Vacuum Society
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• v.20 no.5
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• pp.361-366
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• 2011

An in-situ, real-time monitoring of GaN epilayers grown by low pressure metalorganic chemical vapor deposition system modified for spectral reflectance was performed. Reflectance spectrums from 190~861 nm were observed using p-polarized light with incident angle of $75^{\circ}$. All reflectance spectrums showed interference oscillation caused by multiple reflection within GaN epilayers, and the spectrum from GaN with low crystalline quality showed weak reflectance intensity and much low amplitude of the oscillation because many defects in GaN resulted in light scattering and absorption. Signal variation of reflected light which was selected around strong constructive wavelength range was also observed during $NH_3$ supplying and $NH_3$ cut-off. There was no significant change in signal intensity when $NH_3$ cut-off for 10 sec, but it showed higher intensity when $NH_3$ was cut off for over 30 sec and its intensity kept unchanged. This result indicates that GaN surface was N-terminated during $NH_3$ supplying but Ga-terminated during $NH_3$ cut-off because of high nitrogen equilibrium vapor pressure of GaN, and metallic Ga-terminated surface caused slightly higher reflectance intensity.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.15 no.6
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• pp.4039-4045
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• 2014

The crystallization behavior of irradiated polypropylene (PP) and the blend is an important parameter for polymer processing. Blends of PP/low density polyethylene (LDPE) with different LDPE contents were prepared by melt mixing in a twin screw extruder. The effect of the LDPE content on the irradiation effectiveness of the PP/LDPE blend with trimethylolpropane-trimetacrylate (TMPTMA) as a crosslinking co-agent was investigated in conjunction with the LDPE loading in the blend. The non-isothermal crystallization and crystal structure were measured by DSC, X-ray diffraction (XRD), and polarized optical microscopy (POM). A decrease in the melting temperature of PP was observed due to irradiation, which may be due to the PP chain scissioning effect of irradiation. The Ozawa component n represents a rod shaped, disc shaped and sphere-shaped geometry of the crystal if the value corresponds to 2, 3 and 4, respectively. Based on Ozawa analysis, the values of n were 3.8 and 2.3 for the pure PP and PP blends with 30 wt% LDPE, respectively. The fact that the crystal geometry of PP changed from spherical to disc and rod shaped was confirmed by Ozawa analysis and POM. The ${\beta}$ form XRD peak of the PP/LDPE blend at $16.1^{\circ}$ disappeared after irradiation due to the crosslinking reaction.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.30 no.8A
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• pp.697-704
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• 2005

In this paper, Passive Temperature Compensation Technology is apply to 8-channel Optical multiplexer with 1000Hz channel spacing. The 8-channel multiplexer is fabricated by connecting three cascaded Mach Zehnder Interferometer(MZI) of optical fiber type, and each interferometer has the wavelength interval of 100GHz, 2000Hz and 4000Hz, respectively. Furthermore, to acquire uniform insertion loss, it is fabricated by using Wavelength Flatten Coupler(WFC) in which the variation of insertion loss is low. $CO_2$ laser to adjust precisely the wavelength. The optical fiber is very sensitive in the thermal variation around. Thus, When fabrication the prototype, it is applied a technique to compensate the optical thermal effect because the center wavelength at the output is shifted according to the thermal variation around. In summary, The prototype composed by eight cascaded MZI has an insertion loss of 5.5 dB, the bandwidth of 0.8nm at 0.5 dB point, and channel crosstalk of 25 dB. Furthermore, the loss dependent on polarization is measured as 0.06dB. Consequently, the output wavelength is shifted within 0.05 m when the surrounding temperature varies until $60^{\circ}C$

• Journal of the Korean earth science society
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• v.26 no.7
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• pp.674-682
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• 2005

The Samsung mine is located in Jeongsan-myeon, Cheongyang-gun, Chungcheongnam-do, and is produces sericite ores. The purpose of this study is to investigate the geology and mineralogy of sericite one and its host-rock together with the alteration processes and age of sericitization. Geological survey, polarizing microscopy, X-ray powder diffraction, electron microprobe analysis, X-ray fluorescent analysis, differential thermal analysis, and K/Ar isotope study have been employed for this study. The mine area is composed of Precambrian granite-gneiss and mica schist, and also Jurassic biotite granite. Serictization has occured within the granite-gneiss, and is interpreted to be formed by hydrothermal alteration. The sericite was formed by the breakdown of orthoclase, plagioclase, and biotite, respectively. With sericitization intensity increase, $SiO_2\;and\;Na_2O$ contents are decreased, while $Al_2O_3\;and\;K_2O$ increased. The formation age of sericite has been determined to be Jurassic, which corresponds well to the intrusion age of the biotite granite nearby.