• Journal of IKEEE
• /
• v.25 no.1
• /
• pp.156-167
• /
• 2021

In this paper, we propose a digital transceiver unit design for in-building of 5G optical repeaters that extends the coverage of 5G mobile communication network services and connects to a stable wireless network in a building. The digital transceiver unit for driving the proposed 5G optical repeater is composed of 4 blocks: a signal processing unit, an RF transceiver unit, an optical input/output unit, and a clock generation unit. The signal processing unit plays an important role, such as a combination of a basic operation of the CPRI interface, a 4-channel antenna signal, and response to external control commands. It also transmits and receives high-quality IQ data through the JESD204B interface. CFR and DPD blocks operate to protect the power amplifier. The RF transmitter/receiver converts the RF signal received from the antenna to AD, is transmitted to the signal processing unit through the JESD204B interface, and DA converts the digital signal transmitted from the signal processing unit to the JESD204B interface and transmits the RF signal to the antenna. The optical input/output unit converts an electric signal into an optical signal and transmits it, and converts the optical signal into an electric signal and receives it. The clock generator suppresses jitter of the synchronous clock supplied from the CPRI interface of the optical input/output unit, and supplies a stable synchronous clock to the signal processing unit and the RF transceiver. Before CPRI connection, a local clock is supplied to operate in a CPRI connection ready state. XCZU9CG-2FFVC900I of Xilinx's MPSoC series was used to evaluate the accuracy of the digital transceiver unit for driving the 5G optical repeater proposed in this paper, and Vivado 2018.3 was used as the design tool. The 5G optical repeater digital transceiver unit proposed in this paper converts the 5G RF signal input to the ADC into digital and transmits it to the JIG through CPRI and outputs the downlink data signal received from the JIG through the CPRI to the DAC. And evaluated the performance. The experimental results showed that flatness, Return Loss, Channel Power, ACLR, EVM, Frequency Error, etc. exceeded the target set value.

• Korean Journal of Crystallography
• /
• v.8 no.1
• /
• pp.38-47
• /
• 1997

A new weighing sensor for the automatic diameter control system of the crystal growth is developed in this study. This weighing sensor measures the frequency of the vibrating element which is lineally changing with respect to weight. The signal and the power of this system are transmitted without any physical contact, so that this sensor offers high accuracy and resolution. This system consists of a string, a sinusoidal wave generator, an automatic amplification adjusting circuit, signal transformers and a PCB. 4 kinds of programs are developed for checking DAC, weight calibration and controlling growth process. The measurements of the standard deviation and the resolution show $\pm0.10g$(measured at every second) and $5{\times}10^{-5}$, respectively, This weighing sensor is effective under high pres-sure of 200 atm, high temperature and vacuum condition. The weighing system can control the temperature in the accuracy of $\pm0.025^{\circ}C$ with the 'signal divider'. The optical quality single crystals of $(YGd)_3Sc_2Ga_3O_{12},\;Er-Y_3Sc_2Al_3O_{12},\;and\;Bi_{12}GeO_{20}$ have been grown by Czo-chralski method using this auto-diameter control system.

• Korean Journal of Mineralogy and Petrology
• /
• v.33 no.1
• /
• pp.11-18
• /
• 2020

High-pressure synchrotron X-ray powder diffraction experiments were performed on natural illite (K_0.65Al₂(Al_0.65Si_3.35)O₁₀(OH)₂) using diamond anvil cell (DAC) under two different pressure transmitting media (PTM), i.e., water and ME41 (methanol:ethanol = 4:1 by volume). When using water as PTM, occasional heating was applied up to about 250℃ while reaching pressure up to 2.7 GPa in order to promote both hydrostatic conditions and intercalation of water molecules into the layer. When using ME41, pressure was reached up to 6.9 GPa at room temperature. Under these conditions, illite did not show any expansion of interlayer distance or phase transitions. Pressure-volume data were used to derive bulk moduli (K₀) of 45(3) GPa under water and 51(3) GPa under ME41 PTM. indicating no difference in compressibility within the analytical error. Linear compressibilities were then calculated to be β^a = 0.0025, β^b = 0.0029, β^c = 0.0144 under ME41 PTM showing the c-axis is ca. six times more compressible than a- and b-axes. These elastic behaviors of illite were compared to muscovite, one of its structural analogues.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.30 no.4C
• /
• pp.230-238
• /
• 2005

An orthogonal frequency division multiplexing (OFDM) system consists of a number of independently modulated subcarriers and, thus, a high peak-to-average power ratio (PAR) can occur when the subcarriers are added coherently. The high PAR brings such disadvantages as an increased complexity of the analog-to-digital (ADC) and digital-to-analog (DAC) converters and a reduced efficiency of the radio frequency (RF) power amplifier. In this paper, we propose a novel PAR reduction scheme called selective mapping of partial tones (SMOPT). The SMOPT scheme has a reduced complexity, lower sensitivity to peak reduction tones (PRT) positions, and a shorter processing time as compared with the conventional tone reservation (TR) scheme. The performance of the SMOPT scheme is analyzed based on the IEEE 802.1la wireless local area network(WLAM) physical layer model. Numerical results show that the SMOPT scheme outperforms the TR scheme under various scenarios.

• Journal of Microbiology and Biotechnology
• /
• v.28 no.11
• /
• pp.1850-1858
• /
• 2018

Glucosamine (GlcN) is widely used in the nutraceutical and pharmaceutical industries. Currently, GlcN is mainly produced by traditional multistep chemical synthesis and acid hydrolysis, which can cause severe environmental pollution, require a long prodution period but a lower yield. The aim of this work was to develop a whole-cell biocatalytic process for the environment-friendly synthesis of glucosamine (GlcN) from N-acetylglucosamine (GlcNAc). We constructed a recombinant Escherichia coli and Bacillus subtilis strains as efficient whole-cell biocatalysts via expression of diacetylchitobiose deacetylase ($Dac_{ph}$) from Pyrococcus furiosus. Although both strains were biocatalytically active, the performance of B. subtilis was better. To enhance GlcN production, optimal reaction conditions were found: B. subtilis whole-cell biocatalyst 18.6 g/l, temperature $40^{\circ}C$, pH 7.5, GlcNAc concentration 50 g/l and reaction time 3 h. Under the above conditions, the maximal titer of GlcN was 35.3 g/l, the molar conversion ratio was 86.8% in 3-L bioreactor. This paper shows an efficient biotransformation process for the biotechnological production of GlcN in B. subtilis that is more environmentally friendly than the traditional multistep chemical synthesis approach. The biocatalytic process described here has the advantage of less environmental pollution and thus has great potential for large-scale production of GlcN in an environment-friendly manner.

• Korean Journal of Environment and Ecology
• /
• v.4 no.1
• /
• pp.23-32
• /
• 1990

To investigate the structure of the pine forest community and the conservation of pine forest in Mt. Sokri, twenty plots of 500$m^2$ size set up by the clumped sampling method. The classification by TWINSPAN and DCA ordination were applied to the study area in order to classify them into several groups based on environmental variables. The plant community was not classified into several groups by above methods in this study area. The successional trends of tree species by both techniques seem to be from Pinus densiflora through Quercus serrata, Fraxinus sieboldiana, Q. aliena, Sorbus alnifolia, Prunus sargentii to Carpinus laxiflora, C. cordata in the canopy layer. and from Rhus trichocarpa, Lindera obtusiloba through Styrax obassia, Acer pseudosieboldiana, Symplocos chinensis for. pilosa to L. erythrocarpa, Viburnum erosum in the understory layer. Pinus densiflora community shall be conserved by the disclimax method, i. e. the broadleaf vegetation in the underlayer of the pine community should be cleared out.

• Journal of the Institute of Electronics and Information Engineers
• /
• v.53 no.8
• /
• pp.113-118
• /
• 2016

In this paper, a read-in integrated circuit (RIIC) for IR scene projectors (IRSPs) adopting a sub-frame control technique is proposed, which minimizes the reduction of the apparent temperature of the IR images projected from IRSPs operating at a frame rate of 30 Hz. The proposed sub-frame control technique significantly reduces the amount of scene data loss on capacitors, which is caused by leakage currents flowing through MOSFET switches during holding periods, by dividing a unit frame into 8 sub-frames and refreshing the same scene data for each sub-frame. A current-drive RIIC was designed for the higher apparent temperature of IR radiated from the emitter, and it receives the scene data as a form of analog voltages from an external DAC. A prototype chip with a $64{\times}32$ RIIC array was fabricated using Magnachip/SKhynix $0.35{\mu}m$ 2-poly 4-metal CMOS process, and the measured maximum output data current is $230.3{\mu}A$. This amount of current ensures the projection of IR images whose maximum apparent temperature is $366.2^{\circ}C$ in the mid-wavelength IR (MWIR) when applied to a prototype emitter having a resistance of $15k{\Omega}$.

• Clean Technology
• /
• v.30 no.2
• /
• pp.123-133
• /
• 2024

Zeolite template carbon (ZTC) was synthesized as an adsorbent to remove low-concentration CH₄ from the atmosphere. The synthesis of ZTC was performed using CH₄ and C₂H₂ as carbon precursors and their impact on adsorption was investigated. ZTC was also synthesized using Y zeolite ion-exchanged with CaCl₂ and LiCl as templates to investigate the effect of using metals in ion exchange. The comparison of the carbon precursors revealed that C₂H₂ had a higher carbon yield than CH₄. The synthesized ZTC exhibited developed micropores due to carbon deposition deep inside the micropores of the zeolite template. The kinetic diameter of C₂H₂ (0.33 nm) is smaller than that of CH₄ (0.38 nm), which allowed for its deposition. The study compared metal precursors used for ion exchange and confirmed that the CaCl₂-based ZTC developed more micropores compared to the LiCl-based ZTC. The ion-exchanged Ca inhibited pore blocking by the carbon precursor, allowing it to enter the pores. The ability of synthesized ZTC to adsorb N₂ and CH₄ at 298 K was investigated. The results showed that CH₄ had a higher overall adsorption amount than N₂. The sample synthesized using C₂H₂ and CaY exhibited the highest N₂ and CH₄ adsorption capacity. However, the sample synthesized with CH₄ had the highest CH₄/N₂ gas uptake ratio, which is a crucial factor in designing an adsorption process. The observed difference was likely caused by the underdevelopment of ultrafine pores that are associated with N₂ adsorption. This resulted in a reduction of N₂ adsorption, leading to an increase in CH₄/N₂ separation.

• Korean Journal of Mineralogy and Petrology
• /
• v.34 no.3
• /
• pp.169-176
• /
• 2021

This study aimed to fundamentally understand structural changes of zeolite under pressure and in the presence of different pressure-transmitting media (PTM) for application studies such as immobilization of heavy metal cation or CO₂ storage using pressure. High-pressure X-ray powder diffraction study was conducted on the zeolite-W (K_6.4Al_6.5Si_25.8O₆₄× 15.3H₂O, K-MER) to understand linear compressibility and the bulk moduli in different PTM conditions. Zeolite-w is a synthetic material having the same framework as natural zeolite merlinoite ((K, Ca_0.5, Ba_0.5, Na)₁₀ Al₁₀Si₂₂O₆₄× 22H₂O). The space group of the sample was identified as I4/mmm belonging to the tetragonal crystal system. Water, carbon dioxide, and silicone-oil were used as pressure-transmitting media. The mixture of sample and each PTM was mounted in a diamond anvil cell (DAC) and then pressurized up to 3 GPa with an increment of ca. 0.5 GPa. Pressure-induced changes of powder diffraction patterns were measured using a synchrotron X-ray light source. Lattice constants, and bulk moduli were calculated using the Le-Bail method and the Birch-Murnaghan equation. In all PTM conditions, linear compressibility of c-axis (𝛽^c) was 0.006(1) GPa^-1 or 0.007(1) GPa^-1. On the other hand, the linear compressibility of a(b)-axis (𝛽^a) was 0.013(1) GPa^-1 in silicone-oil run, which is twice more compressible than the a(b)-axis in water and carbon dioxide runs, 𝛽^a = 0.006(1) GPa^-1. The bulk moduli were measured as 50(3) GPa, 52(3) GPa, and 29(2) GPa in water, carbon dioxide, and silicone-oil run, respectively. The orthorhombicities of ac-plane in the water, and carbon dioxide runs were comparatively constant, near 0.350~0.353, whereas the value decreased abruptly in the silicone-oil run following formula, y = -0.005(1)x + 0.351(1) by non-penetrating pressure fluid condition.

• Radiation Oncology Journal
• /
• v.28 no.4
• /
• pp.219-223
• /
• 2010

Purpose: To test the radiosensitizing effect of the newly synthesized novel histone deacetylase inhibitor, SK-7041 in vivo. Materials and Method: The RIF-l cell line was implanted into the back of a 6-week-old female C3H mouse, intradermally, The mice were grouped into control, drug, radiation (RT), and RT+drug group. SK-7041, 4 mg/kg was administered intraperitoneally for six cycles every 12 hours for mice in the drug and RT+drug group, An identical volume of phosphate buffered saline (PBS) was administered at the same frequency to mice in the control and RT groups. A single 5 Gy fraction was delivered to mice in RT and RT+drug group 6 hours after the fourth delivery. The volume of the implanted tumor was measured every 2~3 days to formulate the growth delay curve. Results: For the control, drug, RT, and RT +drug groups, the average duration for implanted tumor to reach a volume of $1,500mm^3$ was 10 days, 10 days, 9 days, and 12 days, respectively. Moreover, the tumor volume on D14 was $276.7mm^3$, $279.9mm^3$, $292.5mm^3$, and $185.5mm^3$, respectively (p=0.0004). The difference for the change in slope for the control and drug versus the RT and RT+drug groups were borderline significant (p=0.0650). Conclusion: The results of this study indicate that SK-7041 has a radiosensitizing effect for the RIF-1 cell line in vivo at a low concentration and this effect may be synergistic. Implementing this result to clinical trial is warranted.