• Journal of the Korean Chemical Society
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• v.61 no.4
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• pp.143-150
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• 2017

Countercurrent oxidation process (COP) was developed and evaluated for treatment of highly concentrated PCB containing insulating oil. The PCB content in insulating oil taken from Haksanmetal company was found to be 1,512 ppm. The COP utilizes a self-sustained flame which propagates itself in a direction counter to the oxygen flow. The flame removes PCBs adsorbed in activated carbon and, at the same time, regenerates activated carbon. The flame temperature was determined from both mass loss of activated carbon and the relative ratio of CO and $CO_2$ exhausted during COP, and showed that its temperature lied in the range of $650-850^{\circ}C$. Removal efficiency of PCBs was achieved above 99.99% for 5% of insulating oil loaded activated carbon with 1 COP in weight ratio. Also, the same removal efficiency was acquired for 60% of insulating oil loaded activated carbon with three consecutive COP. In addition, specific surface area of activated carbon during COP was recovered to almost similar value of virgin activated carbon. It proved that the COP was much effective in removing high concentration of PCBs in insulating oil easily and affordably.

• Korean Journal of Ecology and Environment
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• v.45 no.3
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• pp.322-328
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• 2012

To estimate the population size of Miho spine roach (Cobitis choii), one of national monument species in Korea, multiple mark-recapture experiments (Jolly-Seber model) by VIE tagging were conducted in the upper region of the Backgok Stream located in the Kum-River system, Korea. Fish sampling was conducted at four different times from October 5 to October 26, 2011. A total of 335 sampling points were sampled, where the species was determined in 217. The population size was estimated to be 6,143 in this study. Compared to a previous report conducted by the Korean Ministry of Environment (2009), the population size of this species has decreased by 41%. The reasons for population decline are thought to be due to loss of microhabitat, sedimentation, water pollution. Consequently, a habitat restoration program is required to protect the microhabitat and recover the population size in this area.

• Journal of Animal Science and Technology
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• v.48 no.6
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• pp.813-818
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• 2006

The objective of this study was to investigate effects of supplementation levels of L-leucine in low-lysine diets on growth performance and meat quality parameters in finishing Duroc pigs. A total of fifty-four pigs with an average initial weight of 74±1kg were allotted to one of three dietary treatments. Each treatment had six replications of three pigs per replicate. The treatment diets included 1)a corn-soybean meal basal diet containing lysine as low as 0.45% (CON), 2) basal diet plus 1.5% L-leucine (LEU 1.5), and 3) basal diet plus 3.0% L-leucine (LEU 3.0). No difference was found in ADG, ADFI and Feed/Gain among treatments. In carcass parameters, dressing precent and back-fat thickness were not affected by L-leucine levels, however, longissimus dorsi area tended to increase by supplementation of L-leucine. Marbling score was significantly higher (P<0.05) in LEU 1.5 and LEU 3.0 than in CON. In meat quality parameters, CIE L* of meat color significantly increased (P<0.05) and crude fat tended to increase by supplementation of L-leucine. However, there was no difference in water holding capacity, cooking loss and shear force value. This study suggests that dietary supplementation of L-leucine in low-lysine diets at the end of finishing period can produce high marbled pork which is preferred by Korean consumers.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.26 no.6
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• pp.557-566
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• 1993

For the purpose of examining the distribution of organic matter in the nearshore surface sediments of Korea, organic carbon, nitrogen, ignition loss, chemical oxygen demand, phaeopigment and total sulphide for 117 surface sediments were measured and analyzed in February, 1993. Organic carbon and nitrogen contents ranged from $0.03\%\;to\;5.41\%$ (average $1.08\%$) and from $0.01\%\;to\;0.44\%$ (average $0.18\%$), respectively. The highest contents with the average $2.18\%$ organic carbon and $0.23\%$ nitrogen were found in the eastern part of the southern coast, while the lowest contents with the average $0.17\%$ organic carbon and $0.03\%$ nitrogen in Kunsan coastal area covering from Kum river to Dongjin river. The principal component analysis using all measured data distinguished the western coast from the eastern part of the southern coast clearly according to organic matter contents, that is, the degree of eutrophication in the sediments. Pusan harbor and the mouth of Masan Bay had high C/N ratio that might be resulted from the input of terrestrial sewage and industrial wastewater. A high concentration of total sulphide distinguished the surface sediment of Masan Bay from that of other areas.

• The Korean Journal of Malacology
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• v.28 no.3
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• pp.225-232
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• 2012

In order to evaluate the relationship of between the contents of inorganic elements in shellfish and surface sediments, we measured the concentration of inorganic elements (As, Ca, Cd, Cr, Fe, Hg, Li, Mn, Ni, P, Pb, Zn) in various shellfish and surface sediments of research area. The enrichment factor (EF) and the index of accumulation rate (Igeo) of the metals showed that the research areas can be classified as moderately polluted, or unpolluted. And also we measured the geochemical characteristics of surface sediments(grain size, chemical oxygen demand (COD), ignition loss (IL) and acid volatile sulfide (AVS). The grain sizes for research areas of surface sediment were similar the ratio of silt and clay in comparison with other sites. The COD and IL in surface sediment ranged from 5.41 to 14.06 mg/g. d.w. (mean $8.78{\pm}3.16$ mg/g d.w.) and from 0.92 to 3.17% (mean $2.08{\pm}0.86%$), respectively. Siginificant differences in metal concentrations also were determinated in the shellfish tissue among the different sites. However, except for metals(Mn, Zn), which showed some elevation of concentrations, the variations in the shellfish tissue were not related to variations in the sediment.

• The Proceeding of the Korean Institute of Electromagnetic Engineering and Science
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• v.14 no.3
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• pp.20-40
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• 2003

Since unloaded Q-value of a high-temperature superconductor(HTS) filter is very high, a bandpass filter(BPF) and a lowpass filter(LPF) with an increase of pole numbers can be fabricated without an increase of an insertion loss(IL) ; recently a 70-pole BPF is developed in USA. They have an abrupt skirt property and an excellent attenuation level for out-of band. Moreover, they can be miniaturized when lumped element resonators or the slow-wave characteristic are used. Technology of fabricating a HTS epitaxial film as well as a film of a 4 inch area also makes the planar type filter with a various structure and an enhanced power handling capability possible. Recently, the HTS filter subsystems composed of a planar-type HTS filters, a GaAs-based LNA and a mini-cryocooler are developed. The extended receiver front- end subsystems for mobile radio communications decrease the noise-figure level of the communication system and the frequency interference interacted adjacent bands, and increase the efficiency of frequency and the capacity of communication system. In this paper, theory for developing the HTS filter, its kinds, its design rules, its characteristics are reviewed. The feature of the research and market trends related to the HTS filter systems for the receiver front-end subsystem of mobile base station are surveyed.

• Korean Journal of Optics and Photonics
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• v.5 no.1
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• pp.166-172
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• 1994

The fiber optic receiver, ETRI APD-FET 1.0, is developed for the application of optical communication. This fiber optic receiver includes PD sub-module and pre-amplifier case. A single lens system is introduced for the PD sub-module. The sub-module consists of the avalenche photodiode(APD), GRIN rod lens, and a single mode fiber. The above components are enclosed into the stainless steel 304L housings. By bevelling the fiber end, the single mode fiber provides less than ~ 28 dB of optical return loss. The area of image focus is controlled by adjusting the length of spacer located in-between the fiber and the GRIN rod lens. The laser welding technique is applied to achieve the maximum coupling efficiency for the joining of each housing. In the pre-amplifier case, GaAs FET pre-amplifier workes for photocurrent amplification and the thermister is mounted to control the APD bias. The performance of ETRI APD-FET1.0 shows the sensitivity of - 30.3 dBm at $10^{-10}$ BER(bit error rate) and 2.5 Gbps optical random signal of $2^{23}-1$ word length. The fiber optic receiver is one of the essensial parts of the transmission module for B-ISDN. Also, the above optical packaging technology will be adapted for the developement of 10 Gbps transmission application 2.5 Gbps 5 Gbps

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.29 no.10
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• pp.758-765
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• 2018

This paper presents a 24-GHz frequency-modulated continuous wave(FMCW) radar transceiver with two Rx and one Tx channels in 65-nm complementary metal-oxide-semiconductor(CMOS) process and implemented it on a radar system using the developed transceiver chip. The transceiver chip includes a $14{\times}$ frequency multiplier, low-noise amplifier, down-conversion mixer, and power amplifier(PA). The transmitter achieves >10 dBm output power from 23.8 to 24.36 GHz and the phase noise is -97.3 GHz/Hz at a 1-MHz offset. The receiver achieves 25.2 dB conversion gain and output $P_{1dB}$ of -31.7 dBm. The transceiver consumes 295 mW of power and occupies an area of $1.63{\times}1.6mm^2$. The radar system is fabricated on a low-loss Duroid printed circuit board(PCB) stacked on the low-cost FR4 PCBs. The chip and antenna are placed on the Duroid PCB with interconnects and bias, gain blocks and FMCW signal-generating circuitry are mounted on the FR4 PCB. The transmit antenna is a $4{\times}4$ patch array with 14.76 dBi gain and receiving antennas are two $4{\times}2$ patch antennas with a gain of 11.77 dBi. The operation of the radar is evaluated and confirmed by detecting the range and azimuthal angle of the corner reflectors.

• Korean Journal of Digital Imaging in Medicine
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• v.12 no.2
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• pp.103-111
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• 2010

A total of 200 hospital employees participated in this study from January 2009 to June 2010. For the survey, each participant was given necessary items for external health exams. Cronbach's alpha was calculated for the survey regarding wireless networks. There was a need for educating data processing workers in the medical field regarding fundamental information prior to wireless network construction. The reason is high scores would be collected, which would reflect knowledge regarding data processing used at hospitals and the differences between paper charts and electronic charts. However, low scores were obtained which reflected knowledge regarding the differences between wired and wireless networks and Mini-PACS. Time for each patient was shortened to a maximum of three minutes and minimum of one minute for treatment and transmitting medical images when comparing pre and post wireless network construction(p < 0.01). Scores from the pre and post construction survey increase 1.98, 1.65, and 1.43 points for activity in the health screening area, usage of space in the health screening vehicle, and patient information storage respectively(p < 0.05). The number of patients receiving external health screenings twelve times was 3,655 prior to construction of a wireless network system. However, the number increased to 4,265 after construction. The increasing percentage was 17% in total. Prior to construction, X-ray images were taken 527 times, but after construction of a wireless network, this number growed to 1,194 and it was 116% increase. The loss of patient's medical treatment charts was reduced from 19.8% to 18.7% after construction. We believe that educating medical workers on Mini-PACS and Mini-OCS Systems will not only increase their efficiency but also make patients receiving better treatment.

• Polymer(Korea)
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• v.35 no.1
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• pp.30-34
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• 2011

In this study, the effects of the electron beam irradiation on the thermal behavior and the abrasion properties of the glass fiber reinforced nylon 12 was investigated. The electron beam irradiation was carried out over a range of irradiation dose from 100 to 600 kGy with additive crosslinking agents such as triallyl cyanurate (TAC), triallyl isocyanurate (TAIC) and trimethylolpropane trimethacrylate (TMPTMA) for enhancing the crosslinking effects. The gel contents were increased dramatically above 200 kGy. It was verified that the degree of crosslinking depends on the radiation dose. The decreases of the melting temperature and the area of endothermic peak were observed as increasing the absorbed dose in the results of DSC analysis. The enhanced thermal stability was confirmed by the increases of decomposition temperature by electron beam irradiation. Furthermore, the negative deviations of the abrasion loss and the abrasion coefficients confirmed the improvement of the abrasion properties of irradiated nylon 12, as evidenced by SEM observation on the abrasion surfaces. The addition of the crosslinking agents to nylon 12 during effectively improved the thermal behavior and the abrasion properties of nylon 12 by the electron beam irradiation.