• Journal of ILASS-Korea
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• v.4 no.3
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• pp.8-14
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• 1999

The characteristics of the breakup process in supercritical spray is investigated during the injection of supercritical sulfur hexafluoride into dissimilar gases at supercritical pressures and subcritical temperature of the injected fluid. The visualization techniques used are backlighting and shadowgraph methods. The spray angles are measured and the breakup and mixing process are observed at near and supercritical conditions. The results show that spray angles are decreased with the in..ease of the ratio of density $(\frac{\rho_f}{\rho_g})$. At the supercritical temperature, the spray angles in atomization region are kept nearly constant such as the typical spray angle in gas injection. The mixing process is changed radically at the temperature where $\frac{d\rho}{dT}=\frac{1}{2}[\frac{d\rho}{dT}]_{max}$ at given pressure.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.4 no.2
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• pp.297-305
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• 2000

It is observed that the initial properties and degradation characteristics on plasma of n/p-MOSFET with polycide and poly-Si as different gate materials under F-N stress and hot electron stress are affected by metal AR(Antenna Ratio) during plasma process. Compared to that of MOS devices with poly-Si gate material, reliability properties on plasma of MOS devices with polycide gate material are improved. This can be explained by that fluorine of tungsten polycide process diffuses through poly-Si into gate oxide and results in additional oxide thickness. The fact that MOS devices with polycide gate material can reduce damages of plasma process shows possibility that polycide gate material can be used as gate material for next generation MOS devices.

• Journal of Fisheries and Marine Sciences Education
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• v.20 no.1
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• pp.127-134
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• 2008

The purpose of this study was to determine content of biogenic amines (Histamine, Cadaverine, Putrescine) in the salted mackerel, canned mackerel, mackerel pike, and freeze dried mackerel pike (Guamegi) collectively, all were purchased in the market. Salted mackerel was purchased at five markets (A, B, C, D, and F market) and stored for 10 days at $4{^{\circ}C}$. At the time of purchase, salted mackerel purchased at markets A, B and C was tested for biogenic amine, yet nothing was detected. However, salt mackerel purchased at market D was tested and the histamine concentration was 0.5 mg/100g. Mackerel from market F, exhibited content levels of 0.5 mg/100g histamine and 1.6 mg/100g cadaverine. Those make certain safety during self-life but that purchased F market gradually increased biogenic amine during storage. Prepared salted mackerel of varying levels of freshness and processing methods were analyzed for biogenic amines. Salting process was performed using functional brine salt. VBN (volatile basic nitrogen) was used to establish freshness levels of salted mackerel. Analyses of mackerel muscle determined the values of freshness to be 9.2 mg/100g (good freshness), 18.2 mg/100g (bad freshness), respectively. After 40 days of storage, the content of histamine, cadaverine, putrescine in the freshness of salted mackerel was 2.0 mg/kg, 2.4 mg/kg and 0 mg/kg, respectively. The content of histamine, cadaverine, putrescine in salted mackerel of poor freshness was 71.3 mg/kg, 22.9 mg/kg and 17.8 mg/kg, respectively. It was concluded the presence of biogenic amines during the salting process of salted mackerel significantly effected freshness of materials. The presence of biogenic amines were detected in mackerel that underwent the salting process after 1 month of storage at $4{^{\circ}C}$. The levels of biogenic amines in the brine salted mackerel were higher than those found in dry, salted mackerel; however, the freshness of fish had an insignificant effect on biogenic amines. The presence of histamine was detected in small quantities in canned mackerel and mackerel pike from three companies. Alternatively, cadaverine and putrescine were not detected. Guamegi, vacuumed packed or sealed with a rope was purchased from three markets (A, B, C seafood company). Guamegi was stored and observed for 180 days at $-20{^{\circ}C}$. Histamine was detected in small quantities in all products stored at $-20{^{\circ}C}$. Levels of histamine was dependent on the types of packaging, rope packaging yielded the highest level. However, other amines were not detected.

• Membrane Journal
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• v.23 no.4
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• pp.267-277
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• 2013

The effect of water back-flushing period (FT) and water back-flushing time (BT) was compared with the previous study of nitrogen back-flushing in viewpoints of resistance of membrane fouling ($R_f$), permeate flux (J), and total permeate volume ($V_T$) in hybrid process of tubular ceramic microfiltration and PES (polyethersulfone) beads loaded $TiO_2$ photocatalyst for advanced drinking water treatment. As FT decreasing, Rf decreased, but J and $V_T$ increased. Turdity treatment efficiency was the maximum at NBF (no back-flushing) and increased a little as FT decreasing in both water and nitrogen back-flushing. Organic matter treatment efficiency was the maximum at FT 4 min in water back-flushing, but increased as FT decreasing in nitrogen back-flushing. As BT increasing, Rf and resistance of reversible membrane fouling ($R_{rf}$) decreased, but J and $V_T$ increased. The turdity treatment efficiency was almost constant beyond 98% in water back-flushing, but increased as BT increasing except NBF in nitrogen. The organic matter treatment efficiency was the maximum at BT 6 sec in water back-flushing, but increased as BT increasing except NBF in nitrogen. The $V_T$ was the maximum at BT 30 and FT 2 min, and optimal condition was BT 30 sec per FT 2 min in this experimental range.

• Asian Journal of Atmospheric Environment
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• v.8 no.1
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• pp.1-14
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• 2014

Migration of methane ($CH_4$) gas from landfills to the surrounding environment negatively affects both humankind and the environment. It is therefore essential to develop management techniques to reduce $CH_4$ emissions from landfills to minimize global warming and to reduce the human risks associated with $CH_4$ gas migration. Oxidation of $CH_4$ in landfill cover soil is the most important strategy for $CH_4$ emissions mitigation. $CH_4$ oxidation occurs naturally in landfill cover soils due to the abundance of methanotrophic bacteria. However, the activities of these bacteria are influenced by several controlling factors. This study attempts to review the important issues associated with the $CH_4$ oxidation process in landfill cover soils. The $CH_4$ oxidation process is highly sensitive to environmental factors and cover soil properties. The comparison of various biotic system techniques indicated that each technique has unique advantages and disadvantages, and the choice of the best technique for a specific application depends on economic constraints, treatment efficiency and landfill operations.

• Korean Chemical Engineering Research
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• v.43 no.6
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• pp.728-739
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• 2005

An experiment and simulation were performed for hydrogen separation of mixtures by PSA (pressure swing adsorption) process on activated carbon. The binary ($H_2/Ar$; 80％/ 20％) and ternary ($H_2/Ar/CH_4$; 60％/ 20％/ 20％) mixtures were used to study the effects of feed composition. The cyclic performances such as purity, recovery, and productivity of 2bed-6step PSA process were experimentally and theoretically compared under non-isothermal and non-adiabatic conditions. The develped process produced the hydrogen with 99％ purity and 75％ recovery from both processes. Therefore, optimal separation condition was referred multicomponent gas mixtures.

• Journal of Sensor Science and Technology
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• v.27 no.2
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• pp.93-98
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• 2018

In this paper, an energy-efficient 11.49-bit successive approximation register (SAR) capacitance-to-digital converter (CDC) for capacitive sensors with a figure of merit (FoM) of 31.6 pJ/conversion-step is presented. The CDC employs a SAR algorithm to obtain low power consumption and a simplified structure. The proposed circuit uses a capacitive sensing amplifier (CSA) and a dynamic latch comparator to achieve parasitic capacitance-insensitive operation. The CSA adopts a correlated double sampling (CDS) technique to reduce flicker (1/f) noise to achieve low-noise characteristics. The SAR algorithm is implemented in dual operating mode, using an 8-bit coarse programmable capacitor array in the capacitance-domain and an 8-bit R-2R digital-to-analog converter (DAC) in the charge-domain. The proposed CDC achieves a wide input capacitance range of 29.4 pF and a high resolution of 0.449 fF. The CDC is fabricated in a $0.18-{\mu}m$ 1P6M complementary metal-oxide-semiconductor (CMOS) process with an active area of 0.55 mm2. The total power consumption of the CDC is $86.4{\mu}W$ with a 1.8-V supply. The SAR CDC achieves a measured 11.49-bit resolution within a conversion time of 1.025 ms and an energy-efficiency FoM of 31.6 pJ/step.

• The Korea Journal of Herbology
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• v.29 no.3
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• pp.19-26
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• 2014

Objectives : Aucklandiae Radix (Muxiang) one of important herbal medicines in oriental medicine, is defined as the dried root of Aucklandia lappa (Asteraceae). Owing to the similarities in the morphology and name, Inulae Radix (Tu-Muxiang) and Vladimiriae Radix (Chuan-Muxiang) as well as Aristolochiae Radix (Qing-Muxiang) originated from other medicinal plants are often used as substitutes and/or adulterants of Aucklandiae Radix. Therefore, a reliable authentication of these herbal medicines is necessarily for the public health and prevention of misuse. Methods : 32 samples of medicinal plants supplying Aucklandiae Radix, Inulae Radix, Vladimiriae Radix, and Aristolochiae Radix were collected in Korea and China. The ITS (Internal transcribed spacer) nucleotide sequences of samples were determined. The PCR primers to amply DNA marker of each herbal medicine were designed basing on the specific ITS regions showing differences in the sequences among medicinal plants. Results : Primer set Al R/IS F designed in this work amplified 220 bp PCR product only in samples of Aucklandiae Radix. In contrast, primer set Ih F/IS R, Vs R/IS F, and AcR F1/Ac R amplified 250 bp product, 356 bp prouct, and 516 bp product respectively to identify Inulae Radix, Vladimiriae Radix, and Aristolochiae Radix. Conclusions : The primers designed basing on the nucleotide sequences of ITS regions appearing differenced in the sequences among medicinal plants amplified the DNA markers for the identification of Aucklandiae Radix, Inulae Radix, Vladimiriae Radix, and Aristolochiae Radix. These herbal medicines were more efficiently identified by multiplex PCR method using all primers in a single PCR process.

• Journal of Korean Society for Quality Management
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• v.51 no.4
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• pp.481-496
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• 2023

Purpose: The main theme of this study is to derive a profit curve by a cubic cost function for nonlinear CVP analysis. According to the analytical approach to derive a nonlinear profit function in this study, it is possible with only the existing cost structure to calculate the profit maximization and downtime point sales unlike the classical CVP analysis. Furthermore, the profit curve by the mathematical model of this study could serve as a tool to quantify the qualitative evaluation of each stage of the industry life cycle. Methods: This study followed the mathematical approach from the cubic cost function model of microeconomics, and using real data of the Bank of Korea Results: The nonlinear profit function suggested by this study is as follows; ${\pi}(x)=-a\left(x-\frac{f}{1-v}\right)^3+(1-v)x-k$ where $a=\frac{1}{3}v\left(\frac{(1-v)}{f}\right)^2,k=f-a\left(1-\frac{f}{1-v \right)^3$ Conclusion: The process and results of this study would be able to contribute not only in practice of nonlinear CVP analysis required in the management accounting or financial management, but also in cost theory of microeconomics. Also, since the life cycle of all industries in Korea was verified to the growth or mature stage, decision makers should pay careful attention to determining life cycle stages and consider the profit curve by the average variable cost ratio over multi periods.

• Journal of the Microelectronics and Packaging Society
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• v.31 no.2
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• pp.9-15
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• 2024

The effect of the residual impurity on the prepreg surface on the wettability of encapsulant for chip on board package was analyzed with microstructure, compositions and chemical bonds using a scanning electron microscope and X-ray photoelectron spectroscopy. As a result, the contact angle of w/ residual impurity sample was measured to be 28° higher than that of w/o residual impurity sample, and the C-O bond was decreased to be 4% lower than that of w/o residual impurity sample. The surface energy of the prepreg decreased because the impurity ions, Na and F, generated by the manufacturing process and wet etching, reacted chemically with the C on the prepreg surface, forming C-F bonds and breaking the C-O bonds on the prepreg surface. Therefore, the wettability of the encapsulant was degraded because the contact angle between the encapsulant and the prepreg was increased.