• Journal of Sensor Science and Technology
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• v.6 no.4
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• pp.252-257
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• 1997

Organic EL devices, which have the sing3e-layer structure of ITO(indium-tin-oxide) /PPV(poly(p-phenylene vinylene))/cathode and the double-layer structure of ITO/PVK (poly(N- vinylcarbazole)) /PPV/cathode, were fabricated and their electro-optical properties were investigated. Experimental results, in single-layer structure, shown that the increment of temperature for thermal conversion of PPV film from $140^{\circ}C$ to $260^{\circ}C$ decreases the maximum luminance from $118.8\;cd/m^{2}$(20V) to $21.14\;cd/m^{2}$(28V) and shift the maximum peak of EL spectrum from 500nm to 580nm. The lower the work function of cathode is, the more the luminance and injection current of device. In double-layer structure, as the concentration of PVK solution decreases from 0.5 wt% to 0.05 wt%, the luminance of device increases from $70.71\;cd/m^{2}$(32V) to $152.7\;cd/m^{2}$(26V).

• The Journal of the Acoustical Society of Korea
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• v.38 no.1
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• pp.1-8
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• 2019

This paper estimated communication parameters according to underwater channel environment of lake for underwater acoustic communication. This paper calculated coherence time and coherence bandwidth through two experiments in actual lake environments. In both experiments, the chirp signal for channel estimation and the BPSK (Binary Phase Shift Keying) signal for calculating the bit error rate were transmitted. In each experiment, the distance between transmitter and receiver was 300 m to 400 m, and 500 m to 600 m. The coherence times calculated in experiment 1 and experiment 2 are 175 msec and 340 msec, and the coherence bandwidths are 10 Hz and 5.71 Hz, respectively. It is confirmed that the experimental results are more appropriate because the synchronization and the bit error rate performance are better only when the length of the synchronization signal and the interval of the pilot signal in the frame are shorter than the coherence time.

• Journal of Korean Society of Disaster and Security
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• v.16 no.1
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• pp.71-80
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• 2023

Fuel cells are low-carbon power sources that can expand distributed energy system and electric vehicle charging infrastructure when installing fuel cells in gas stations. In order to ensure safety for fuel cells in gas stations, quantitative risk assessments were conducted after deriving accident scenarios based on accident data of domestic and foreign gas stations and fuel cells. It calculates the expected extent of damage from fire and explosion that can occur in reality, not the worst accident scenario, and analyzes the damage impact. The separation distance of more than 9.0 m from a dispenser, 15.5 m from a car under refueling, 4.1 m from the ventilation pipe, 1.1 m from the gas adjustment device prevent the severe damage caused by the expected accident. This study result can be used to deploy fuel cells in gas stations and establish safety measures.

• Journal of Radiopharmaceuticals and Molecular Probes
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• v.8 no.2
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• pp.71-76
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• 2022

Indigenous diagnostic dose of ¹³¹I-labeled meta-iodobenzylguanidine ([¹³¹I]mIBG) was prepared via Cu⁺ catalyzed isotope exchange reaction generated in situ by sodium metabisulfite for imaging of neuroblastoma tumor. [¹³¹I]mIBG was produced in overall 85-90% radiochemical yield. The average amount of radioactivity of [¹³¹I]mIBG was 2164 MBq (1998-2331MBq) with an average specific activity > 1000 MBq/mg at the end of synthesis. The radiochemical purity was ≥ 99.9% after purification through Dowex-1 × 8 ion exchange resin (100-150 mesh) at the date of preparation. The stability of [¹³¹I]mIBG at concentration 480-555 MBq/mL was > 97% at 4 ℃ after 4 days. The room temperature (25 ℃) stability of [¹³¹I]mIBG was > 98% after 24 h. Biodistribution of [¹³¹I]mIBG in patient showed uptake in salivary glands, liver, spleen and excreted though urinary bladder. Neuroendocrine medicated uptake into tumor lesion and metastatic sites were noted which strongly correlate with the morphological abnormalities of patient.

• Food Science and Preservation
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• v.18 no.4
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• pp.590-596
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• 2011

Pimpinella brachycarpa, called as cham-na-mul in Korea, is an edible popular herb. However, the study of biological activity of P. brachycarpa is still rudimentary in worldwide. In this study, from the cultivated P. brachycarpa, we prepared the methanol extract and its subsequent solvent fractions, and their antimicrobial, antioxidation, and anti-proliferative activities were evaluated. The fraction yields of n-hexane (H), methylene chloride (EC), ethylacetate (EA), butanol (B), and water residue (W) from the methanol extract were 18.71, 0.7, 0.56, 4.57, and 71.51%, respectively. Analysis of total flavonoid and total polyphenol showed that the EA fraction contained the highest contents (89.23 and 200 mg/g), and the W residue has the lowest contents (19.6 and 2.27 mg/g) among the factions. In antimicrobial activity assay, the EA fraction showed a broad-range antibacterial activity, while the H fraction is effective against gram positive bacteria. In antioxidation activity assay, EA and B fraction showed strong DPPH anion and ABTS cation scavenging activities including reducing power, and Hand MC fraction showed effective nitrite scavenging activity (71.43~83.82 ${\mu}g$/mL of $IC_{50}$). In a while, only B fraction showed strong anti-proliferative activity against human colorectal cancer HCT-116 (166 ${\mu}g$/mL of $IC_{50}$) as a dose-dependent manner up to 200 ${\mu}g$/mL. These results suggest that the EA and B fraction of P. brachycarpa could be developed as functional food ingredients.

• The Pure and Applied Mathematics
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• v.10 no.2
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• pp.71-102
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• 2003

The purpose of this paper is to study the geometry of null curves in a 6-dimensional semi-Riemannian manifold $M_q$ of index q, since the general n-dimensional cases are too complicated. We show that it is possible to construct three types of Frenet equations of null curves in $M_q$, supported by one example. We find each types of Frenet equations invariant under any causal change. And we discuss some properties of null curves in $M_q$.

• Bulletin of the Korean Chemical Society
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• v.35 no.5
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• pp.1485-1490
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• 2014

We have designed and developed a new ladder type tetrafused ${\pi}$-conjugated building block such as dihydroindolo[3,2-b]indole (DINI) and investigated its role as an electron rich unit. The photovoltaic properties of a new semiconducting ${\pi}$-conjugated polymer, poly[[5,10-bisoctyl-5,10-dihydroindolo[3,2-b]indole-[5,6- bis(octyloxy)-4,7-di(thiophen-2-yl)benzo[c][1,2,5]thiadiazole]], represented by PDINI-OBTC8 are described. The new polymer PDINI-OBTC8 was synthesized in donor-acceptor (D-A) fashion, where fused ${\pi}$-conjugated tetracyclic DINI, and 5,6-bis(octyloxy)-4,7-di(thiophen-2-yl) benzo[c][1,2,5]thiadiazole (OBTC8) were employed as electron rich (donor) and electron deficient (acceptor) moieties, respectively. The conventional bulk heterojunction (BHJ) device structure ITO/PEDOT:PSS/PDINI-OBTC8:PCB71M/LiF/Al was utilized to fabricate polymer solar cells (PSCs), which comprises the blend of PDINI-OBTC8 and [6,6]-phenyl-$C_{71}$-butyric acid methyl ester ($PC_{71}BM$) in BHJ network. A BHJ PSC that contain PDINI-OBTC8 delivered power conversion efficiency (PCE) value of 1.68% with 1 vol% of 1,8-diidooctane (DIO) under the illumination of A.M 1.5G 100 $mW/cm^2$.

• Journal of the Korean Applied Science and Technology
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• v.34 no.4
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• pp.986-994
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• 2017

In this paper, $CO_2$ absorption of scrubber was tested for removal of high concentration $CO_2$. Liquid to gas ratio($18L/m^3$) and Superficial velocity(0.14 m/s) was determined through Lab-scale test. As flow rates increase 1, 2, 3, 4 and $5m^3/min$, $CO_2$ removal efficiency decrease 98.47%, 96.46%, 92.95%, 89.71% and 85.49%. Also, the scrubber operation made energy improvement(5.4%), energy saving(11.5 TOE/year) and greenhouse gases reduction(6.5 TC/year).

• Animal Bioscience
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• v.36 no.3
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• pp.492-497
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• 2023

Objective: The objectives were to demonstrate that the nitrogen and energy in pig urine supplemented with hydrochloric acid (HCl) are not volatilized and to determine the minimum amount of HCl required for nitrogen preservation from pig urine. Methods: In Exp. 1, urine samples of 3.0 L each with 5 different nitrogen concentrations were divided into 2 groups: 1.5 L of urine added with i) 100 mL of distilled water or ii) 100 mL of 6 N HCl. The urine in open plastic containers was placed on a laboratory table at room temperature for 10 d. The weight, nitrogen concentration, and gross energy concentration of the urine samples were determined every 2 d. In Exp. 2, three urine samples with different nitrogen concentrations were added with different amounts of 6 N HCl to obtain varying pH values. All urine samples were placed on a laboratory table for 5 d followed by nitrogen analysis. Results: Nitrogen amounts in urine supplemented with distilled water decreased linearly with time, whereas those supplemented with 6 N HCl remained constant. Based on the linear broken-line analysis, nitrogen was not volatilized at a pH below 5.12 (standard error = 0.71 and p<0.01). In Exp. 3, an equation for determining the amount of 6 N HCl to preserve nitrogen in pig urine was developed: additional 6 N HCl (mL) to 100 mL of urine = 3.83×nitrogen in urine (g/100 mL)+0.71 with R² = 0.96 and p<0.01. If 62.7 g/d of nitrogen is excreted, at least 240 mL of 6 N HCl should be added to the urine collection container. Conclusion: Nitrogen in pig urine is not volatilized at a pH below 5.12 at room temperature and the amount of 6 N HCl required for nitrogen preservation may be up to 240 mL per day for a 110-kg pig depending on urinary nitrogen excretion.

• Journal of the Korean Association of Geographic Information Studies
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• v.18 no.1
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• pp.135-146
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• 2015

This study was carried out to understand ecological characteristics of Korean goral such as home range, seasonal home range and habitat use and used for Korean goral restoration and conservation, through a pair of gorals in the north Gyeongbuk province of Korea. With data from GPS collars, we analyzed the behavioral characteristics of the endangered Korean gorals(n=2) in Uljin area from June 2013 to July 2014. As a result, their home range was $1.38{\pm}0.24km^2$ in MCP 95%, $0.81{\pm}0.09km^2$ in FK 95% and $0.15{\pm}0.16km^2$ in FK 50% (t=8.118, p>0.05). Seasonal home range for MCP 95% was $0.74{\pm}0.31km^2$ > (winter) > $0.71{\pm}0.27km^2$ (spring) > $0.61{\pm}0.06km^2$ (autumn) > $0.27{\pm}0.04km^2$ (summer) (F=2.135 p>0.05). It showed that home range in winter was the largest and that in summer was the smallest. Mean elevation of male for seasonal habitat use was $440.18{\pm}71.32m$ in summer and that of female was $727.25{\pm}99.98m$ in spring. The lowest altitude for male was $372.72{\pm}70.79$ and female was $664.60{\pm}139.71m$. It meant that there were seasonal change and thus annual and seasonal behavior characteristics for both sexes had different correlation according to elevation change. Although in this study the correlation with prey in habitat and the changes of habitat disturbance were not clearly investigated, We could understand goral home range and habitat use through research data.