• Journal of The Korean Society of Grassland and Forage Science
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• v.7 no.3
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• pp.162-167
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• 1987

This experiment was conducted to determine the effect of the feeding value for the wild legumes silage-making with additives. The chopped Kudzu (Puerarie thunbergii Bentham) of wild legumes was ensiled by the conventional method in the small experimental silo of 2 liters. The additives used in the present experiments were water (8%),water (8%) plus corn starch (3%) and water (8%) plus glucose (3%). These additives as well as that of control without additive were set up and these silage were compared with the conventional corn silage. The fermentative qualities and the characteristic of fiber (neutral detergent fiber, NDF; acid detergent fiber, ADF; acid detergent lignin, ADL) of silage produced was determined by chemical analysis, and dry matter digestibility (DMD) was evaluated by pepsin-cellulase technique. The results obtained are summarized as follows: 1 The weight of Kudzu silage was lost under the 10% for all the treatments. 2 In degree of pH for the Kudzu silages with glucose, starch, control and water treatments were high 3.80,4.04,4.57 and 5.34, respectively.

• Applied Chemistry for Engineering
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• v.25 no.4
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• pp.418-424
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• 2014

The improved thermal stability and anti-oxidation properties of Lyocell fiber were studied based on flame retardant treatment by using NaCl/$H_3PO_4$ solution. The optimized conditions of flame retardant treatment were studied on various maxing ratio of NaCl and $H_3PO_4$ and the mechanism was proposed through experimental results of thermal stability anti-oxidation. The IPDT (integral procedural decomposition temperature), LOI (limited oxygen index) and $E_a$ (activation energy) increased 23, 30 and 24% respectively via flame retardant treatment. It is noted that thermal stability and anti-oxidation improved based on char and carbon layer formation by dehydrogenation and dissociation of C-C bond resulting the hindrance of oxygen and heat energy into polymer resin. The optimized conditions for efficient flame retardant property of Lyocell fiber were provided using NaCl/$H_3PO_4$ solution and the mechanism was also studied based on experimental results such as IDT (initial decomposition temperature), IPDT, LOI and $E_a$.

• Journal of Korean Society on Water Environment
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• v.24 no.4
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• pp.423-429
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• 2008

Microfiltration (MF) and ultrafiltration (UF) processes for removal of particulate materials (i.e., turbidity, microorganisms and viruses) have been used to produce drinking water with higher quality. As membrane filtration technique has become widely applied for drinking water treatment, the importance of membrane integrity test (MIT) has also been increasingly emphasized. The results of pressure decay test (PDT) were presented in the paper to monitor membrane integrity. In this paper the PDT was carried out with deliberately-defected membrane fibers to evaluate the sensitivity of PDT on membrane fiber damage. Variation of pressure decay rate and removal rate were investigated to evaluate the impact of defection (defection ratio) and pore size of membrane. The membrane integrity could be successfully monitored by the PDT. The pressure decay rate varied from $0.002{\sim}0.189kg_f/cm^2hr$ with the initial pressure ranged from 0.2 to $1.0kg_f/cm^2hr$. Higher initial pressure which provided with higher pressure decay rate was preferred to evaluate the defection of membrane fiber. As for the particle removal rate, the Log Removal Rate (LRV) of kaolin solution decreased significantly from 3.78 to 2.31 when one fiber out of 3,200 fibers was cut. The membranes with different pore size were tested to evaluate virus removal efficiency. The virus removal rate of the MF membrane ($0.1{\mu}m$) was about 30% although the poliovirus was smaller than the pore size of the MF membrane, indicating that the removal rate was much lower than Korea Water Works Association (KWWA) certificate LRV of 1.5.

• Fire Science and Engineering
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• v.29 no.2
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• pp.25-32
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• 2015

The improved thermal stability and anti-oxidation properties of lyocell fiber were studied based on flame retardant treatment by using $Na_3PO_4$ solution. The optimized conditions of flame retardant treatment were studied on various concentrations of $Na_3PO_4$ and the mechanism was proposed through experimental results of thermal stability and anti-oxidation. The integral procedural decomposition temperature (IPDT), limiting oxygen index (LOI) and activation energy ($E_a$) increased 30, 160% respectively via flame retardant treatment. It is noted that thermal stability and anti-oxidation improved based on char and carbon layer formation by dehydrogenation and dissociation of C-C bond resulting the hindrance of oxygen and heat energy into polymer resin. The optimized conditions for efficient flame retardant property of lyocell fiber were provided using $Na_3PO_4$ solution and the mechanism was also studied based on experimental results such as initial decomposition temperature (IDT), IPDT, LOI and $E_a$.

• Korean Journal of Food Science and Technology
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• v.28 no.3
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• pp.506-513
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• 1996

Soybean hull was microparticulated at cut-off wheel speed of 9,000 rpm and air-classified into fine and coarse fraction at air classifying wheel speeds (ACWS) of 10.000, 15,000 and 20,000 rpm. respectively. Proximate analysis of the coarse and fine fractions of the microparticulated/air-classified soybean hull showed that ash, protein and lipid were enriched in the coarse fractions and carbohydrates in the fine fraction. Dietary fiber were enriched in coarse fractions and dietary fiber and dietary fiber content increased with decreasing ACWS. Mean particle size of fine fractions ranged from $3.1{\mu}m\;to\;5.5{\mu}m$ that of coarse fractions ranged from $9.9{\mu}m\;to\;20.0{\mu}m$ and both increased with decreasing ACWS. The particles were mostly oval-shaped regardless of the fractions. Generally the fraction of low ACWS showed higher viscosity. In water holding capacity, oil absorption and emulsion capacity, there was significant difference between coarse and fine fractions while there was no significant difference as a function of different ACWS. Oil absorption of flying batter was decreased significantly in the fraction of ACWS 15,000. when cakes and cooking were prepared partially substituted with soybean hull fraction, there was no significant changes on their physical and sensory properties up to 10% substitution.

• Korean Journal of Optics and Photonics
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• v.12 no.2
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• pp.135-142
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• 2001

Recently, plastic optical fiber draws a lot of attention as a new transmission medium for local area network (LAN) and home network applications. As PMMA based GI-POF (Graded Index Plastic Optical Fiber) has very low loss at about 500 nm and 650 nm wavelengths, it is very important to have a compact ultra short optical pulse source at these wavelength windows. In this paper, we have investigated detailed characteristics of gain switched laser system by using a commercially available low cost RF devices and an InGaAlP Fabry Perot semiconductor laser operating at 650 nm wavelength. The shortest optical 'pulse obtained was 33 psec with 1 GHz repetition rate. Depending on the DC bias current and the modulation frequency, the FWHM and the pulse energy of the gain switched pulses show 33.3-82.8 psec and 0.97-9.69 pI respectively. Also, the spectral bandwidths for CW and gain switched operations are 0.44 nm and 1.50 nm. We believe that these results are quite useful for high bit rate optical transmission applications with PMMA based plastic optical fibers in addition to estimate properties of ultra fast optical components and electro-optic devices. vices.

• Journal of Industrial Convergence
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• v.21 no.2
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• pp.93-101
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• 2023

In this study, the physical and chemical fiber damage caused by knives, scissors, and chemicals was analyzed and used as technical data to determine the cause of the damage. Using 4 types of knives, 5 types of scissors and 4 types of chemicals(Sulfuric Acid, Hydrochloric Acid, Sodium Hydroxide, Potassium Hydroxide) physical and chemical to Cotton, Wool, Polyester, Rayon, T/C (Polyester 50%, Cotton 50%), T/W (Polyester 50%, Wool 50%) Damages were created and analyzed for damage caused by tools and chemicals. For penetrating damage caused by knives and scissors, 'V' type damage was generally seen when the blade part was penetrated, 'T', 'ㅁ', ''C' type damage was found, and in the case of scissors, 'Y' ' This type of damage was common. Fiber damage caused by chemicals showed various damage such as remanent trace, corrosion, degraded, contracting, and color changes. Physical damage of fibers showed differences in characteristics according to the shape characteristics of tools, and chemical damage showed differences in characteristics according to chemicals and types of fibers.

• Composites Research
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• v.19 no.1
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• pp.29-35
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• 2006

The avoidance of enemy's radar detection is very important issue in the modem electronic weapon system. Researchers have studied to minimize reflected signals of radar. In this research, two types of radar absorbing structure (RAS), 'C'-type shell and 'U'-type shell, were fabricated using fiber-reinforced composite materials and their radar cross section (RCS) were evaluated. The absorption layer was composed of glass fiber reinforced epoxy and nano size carbon-black, and the reflection layer was fabricated with carbon fiber reinforced epoxy. During their manufacturing process, undesired thermal deformation (so called spring-back) was observed. In order to reduce spring-back, the bending angle of mold was controlled by a series of experiments. The spring-back of parts fabricated by using compensated mold was predicted by finite element analysis (ANSYS). The RCS of RAS shells were measured by compact range and predicted by physical optics method. The measured RCS data was well matched with the predicted data.

• Composites Research
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• v.37 no.3
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• pp.162-169
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• 2024

In this study, PAN(polyacrylonitrile)-based precursor fibers were produced through a wet-spinning process, and their morphologies and graphitization behavior were investigated in the presence of two graphitization catalysts (Ca, Ni). The graphitization catalysts were introduced into the formed pores during hot-water stretching of wet-spun PAN-based precursor fibers. The catalytic effects of graphitization catalysts were examined through crystal structure and Raman analysis. At a relatively low temperature of 1500℃, the graphitization was not significantly affected, whereas at a high temperature of 2400℃, the obtained I_D/I_G value of graphite fiber (GF-Ni100) was decreased by about twice (~0.28) compared to the untreated fibers (GF-AS~0.54). By comparing the I_D/I_G values (GF-Ca100~0.42: GF-Ni100~0.28) of Ca and Ni graphitization catalyst, it was found that the degree of graphitization of Ni graphitization catalyst showed higher influence than that of Ca graphitization catalyst. Moreover, 2D band was also observed, indicating that the graphite plane structures composed of multiple layers were developed. XRD results confirmed that the crystal inter-planar distance (d₀₀₂) of the graphite crystal was slightly decreased after the treatment with the graphitization catalyst, But, the crystal size of Ca-treated graphite fiber (GF-Ca100) was increased by up to ~5 nm.

• Nuclear Engineering and Technology
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• v.56 no.6
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• pp.2182-2189
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• 2024

The high-purity germanium gamma-ray spectrometer was used to measure the radioisotope in surface water of lakes in a Chinee petroleum industrial area. 92 samples were collected from surface water of three lakes. Activity concentrations of ²³²Th, ²²⁶Ra and ⁴⁰K in three lakes were measured, distributed in the range of 101.8-209.4, 192.1-224.9 and 335.0-548.9 mBq/L, respectively. Results were all within the limits of WHO and China. Potential environmental and health risks were assessed by calculating some radiation hazard indicators, radium equivalent index, annual effective dose, excess lifetime cancer risk, absorbed dose rate, external hazard index, internal hazard index, annual gonadal dose equivalent, activity utilization index and representative gamma index, which ranged 0.38-0.54 Bq/L, 0.06-0.08 mSv/y, 0.23 × 10^-3-0.31 × 10^-3, 0.17-0.24 nGy/h, 1.01 × 10^-3-1.46 × 10^-3, 1.55 × 10^-3-2.02 × 10^-3, 1.16-1.66 μSv/y, 3.13 × 10^-3-4.45 × 10^-3 and 2.60 × 10^-3-3.77 × 10^-3. The results were all at acceptable levels, meaning no impact on human health. The relationship between the electrical conductivity of surface water and the activity concentration of ²³²Th, ²²⁶Ra and ⁴⁰K was evaluated. The electrical conductivity value was 0.241-0.369 mS/cm, showing a significant correlation coefficient between ²²⁶Ra and ⁴⁰K and electrical conductivity. Multivariate statistical methods were used to determine the relationship between the activity concentrations of ²³²Th, ²²⁶Ra, and ⁴⁰K, radiation hazard indicators and electrical conductivity.