• Bulletin of the Korean Space Science Society
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• 2010.04a
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• pp.32.1-32.1
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• 2010

The BVR CCD observations of the solar-type contact binary GW Cephei, known as very active dynamically and photometrically, has been made for 20 nights from Nov. 03, 2008 to Dec. 31, 2008 with 1-m reflector of Jincheon station of Chungbuk National University Observatory. A total of 2035 measurements (B: 647, V: 722, R: 666) were obtained to secure new multi-color light curves. From our observations fifteen times of minimum light were newly determined. In this paper both a new period study and an intensive light synthesis were made. Our results will be compared and discussed with the latest thorough studies of the system by Lee et al. (2010).

• Proceedings of the Korean Vacuum Society Conference
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• 2010.02a
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• pp.127-127
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• 2010

Owing to many advantages on indirect intersubband absorption from the hole miniband to the electron miniband based on the type-II band alignment in InAs/GaSb strained-layer superlattice (SLS), InAs/GaSb SLS infrared photodetector (SLIP) has emerged as a promising system to realize high-detectivity quantum photodetector operating up to room temperature in the spectral range of mid-infrared (MIR) to far-infrared (FIR). In particular, n-barrier-n (n-B-n) structure designed for blocking the majority-carrier dark current makes it possible for MIR/FIR dual-band SLIP whose photoresponse (PR) band can be exclusively selected by the bias polarity. In this study, we present the MIR and FIR photoresponse (PR) mechanism identified by dual-band PR spectra and photoluminescence (PL) profiles taken from InAs/GaSb SLIP. In the MIR/FIR PR spectra measured by changing bias polarity, each spectrum individually shows a series of distinctive peaks related to the transitions from the hole subbands to the conduction one. The PR mechanism at each polarity is discussed in terms of diffusion current, and a superposition of MIR-PR in the FIR-PR spectrum is explained by tunnelling of electrons activated in MIR-SLS. The effective FIR-PR spectrum decomposed into three curves for HH1, LH1, and HH2 has revealed the edge energies of 120, 170, and 220 meV, respectively, and the temperature variation of the MIR-PR edge energies shows that the temperature behavior of the SLS systems can be approximately expressed by the Varshni empirical equation.

• Journal of the Korean Electrochemical Society
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• v.4 no.3
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• pp.113-117
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• 2001

Specific capacitance and charge-discharge rate of EDLC using activated carbon electrode were affected by the compositions of electrolytes, the conditions of charge-discharge and physical properties of activated carbon materials. The activated carbon electrode was prepared by dip coating method. Charge-discharge test and electrochemical experiments were carried out for various kinds of organic electrolytes. Effects of charge and discharge current density on the specific capacitance were studied. Characteristics of leakage current, self-discharge and time-voltage curves in optimum conditions of organic electrolytes were compared with conventional $1M-Et_4NBF_4/PC$ electrolyte. The EDLC using MSP-20(specific surface area: $2000m^2/g$) electrode and $1M-LiPF_6/PC-DEC(1:1)$ was exhibited th highest specific capacitance of 130F/g and low polarization resistances. The EDLC using MSP-20 electrode at $1M-LiPF_6/PC-DEC(1:1)$ was small leak current of 0.0004A for 15min, long voltage retention of 0.8V after 100h and linear time-voltage curves with small IR-drop.

• Journal of the Korean institute of surface engineering
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• v.34 no.5
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• pp.465-474
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• 2001

Type 304SS coatings were performed at 200$\square$ onto AISI 1045 carbon steel substrate using unbalanced magnetron sputtering (UBMS) with an austenitic AISI 304 stainless steel (SS) target of 100mm diameter. The total deposition pressure in the active Ar gas was 2$\times$10$^{-3}$ Torr. Coatings were done at various target power densities and bias voltages. Chemical compositions of metallic elements of the coatings were measured by energy dispersive X-rays spectroscopy (EDS). The structure and the morphology of Type 304SS coatings were investigated by means of X-ray diffraction (XRD) and scanning electron microscopy (SEM). Corrosion properties of the coated specimens were examined using electrochemical polarization measurements and electrochemical impedance spectroscopy in a deaerated 3.5% NaCl solution. The porosity rate was obtained from a comparison of the dc polarization resistance of the uncoated and coated substrates. Scratch adhesion testing was used to compare the critical loads for different coatings. XRD results showed that the sputtered films exhibit a ferritic b.c.c. $\alpha$-phase. Potentiodynamic polarization curves indicated that all samples had much higher corrosion potential and better corrosion resistance than the bare steel substrate. The corrosion performance increased with increasing power density and the adhesion was enhanced at the bias voltage of -50V. An improvement in the corrosion resistance can be obtained with a better coating adhesion. Finally, an optimized deposition condition for corrosion protection was found as $40W/cm^2$ and -50V.

• Bulletin of the Korean Mathematical Society
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• v.26 no.2
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• pp.169-173
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• 1989

Let V={(x,y,z):f=z$^{n}$ -npz+(n-1)q=0 for n .geq. 3} be a compled analytic subvariety of a polydisc in $C^{3}$ where p=p(x,y) and q=q(x,y) are holomorphic near (x,y)=(0,0) and f is an irreducible Weierstrass polynomial in z of multiplicity n. Suppose that V has an isolated singular point at the origin. Recall that the z-discriminant of f is D(f)=c(p$^{n}$ -q$^{n-1}$) for some number c. Suppose that D(f) is square-free. then we prove that by Theorem 2.1 .mu.(p$^{n}$ -q$^{n-1}$)=.mu.(f)-(n-1)+n(n-2)I(p,q)+1 where .mu.(f), .mu. p$^{n}$ -q$^{n-1}$are the corresponding Milnor numbers of f, p$^{n}$ -q$^{n-1}$, respectively and I(p,q) is the intersection number of p and q at the origin. By one of applications suppose that W$_{t}$ ={(x,y,z):g$_{t}$ =z$^{n}$ -np$_{t}$ $^{n-1}$z+(n-1)q$_{t}$ $^{n-1}$=0} is a smooth family of complex analytic varieties near t=0 each of which has an isolated singularity at the origin, satisfying that the z-discriminant of g$_{t}$ , that is, D(g$_{t}$ ) is square-free. If .mu.(g$_{t}$ ) are constant near t=0, then we prove that the family of plane curves, D(g$_{t}$ ) are equisingular and also D(f$_{t}$ ) are equisingular near t=0 where f$_{t}$ =z$^{n}$ -np$_{t}$ z+(n-1)q$_{t}$ =0.}$ =0.

• Herbal Formula Science
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• v.21 no.1
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• pp.177-185
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• 2013

Objectives : Leejung-tang (Lizhong-tang) has been used for treatment of gastrointestinal disorders in Korea. In this study, we performed quantification analysis of five marker components, liquiritin, ginsenoside Rb1, ginsenoside Rg1, glycyrrhizin, and 6-gingerol in Leejung-tang using a ultra performance liquid chromatography- electrospray ionization-mass spectrometer (UPLC-ESI-MS). In addition, we evaluated antioxidant activity of Leejung- tang. Methods : The column for separation of five constituents used a UPLC BEH C18 ($100{\times}2.1mm$, $1.7{\mu}m$) maintained at $45^{\circ}C$. The mobile phase consisted of two solvent systems, 0.1% (v/v) formic acid in H2O (A) and CH3CN (B) by gradient flow. The flow rate was 0.3 mL/min with detection at mass spectrometer. The antioxidative activities conduct an experiment on 2,2'-azinobis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) and 2,2-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging activities of Leejung-tang. Results : Calibration curves of five marker compounds were acquired with r2 values > 0.99. The amount of the five compounds in Leejung-tang were 0.07 - 0.84 mg/g. The concentration required for 50% reduction (RC50) against ABTS radical was 119.02 ug/mL. In addition, the scavenging against DPPH radical of Leejung-tang was 11.4%, 14.5%, 19.8%, 29.6%, and 49.2% at 25 ug/mL, $50{\mu}g/mL$, $100{\mu}g/mL$, $200{\mu}g/mL$, and $400{\mu}g/mL$, respectively. Conclusions : The established LC-MS/MS method will be helpful to improve quality control of Leejung-tang. In addition, Leejung-tang is a potential antioxidant therapeutic agent.

• Industrial Engineering and Management Systems
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• v.10 no.3
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• pp.185-190
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• 2011

A driver interacts directly with the car seat at all times. There are ergonomic characteristics that have to be followed to produce comfortable seats. However, most of previous researches focused on either static or dynamic condition only. In addition, research on car seat development is critically lacking although Malaysia herself manufactures its own car. Hence, this paper integrates objective measurements and subjective evaluation to predict seat discomfort. The objective measurements consider both static and dynamic conditions. Steven's psychophysics power law has been used in which after expansion; ${\psi}\;=\;a+b{\varphi}_s^{\alpha}+c{\varphi}_v^{\beta}$ where ${\psi}$ is discomfort sensation, ${\varphi}_s^{\alpha}$ is static modality with exponent ${\alpha}$ and ${\varphi}_v^{\beta}$ is dynamic modality with exponent ${\beta}$. The subjects in this study were local and the cars used were Malaysian made compact car. Static objective measurement was the seat pressure distribution measurement. The experiment was carried out on the driver's seat in a real car with the engine turned off. Meanwhile, the dynamic objective measurement was carried out in a moving car on real roads. During pressure distribution and vibration transmissibility experiments, subjects were requested to evaluate their discomfort levels using vehicle seat discomfort survey questionnaire together with body map diagram. From subjective evaluations, seat pressure and vibration dose values exponent for static modality ${\alpha}$ = 1.51 and exponent for dynamic modality ${\beta}$ = 1.24 were produced. The curves produced from the $E_{q.s}$ showed better $R_{-sq}$ values (99%) when both static and dynamic modalities were considered together as compared to Eq. with single modality only (static or dynamic only R-Sq = 95%). In conclusion, car seat discomfort prediction gives better result when seat development considered both static and dynamic modalities; and using ergonomic approach.

• Korean Journal of Pharmacognosy
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• v.47 no.1
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• pp.62-72
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• 2016

Banhasasim-tang is a well-known traditional Korean herbal formula and has been used clinically for the treatment of gastric disease, including acute and chronic gastritis, diarrhea and gastric ulcers in Korea. In this study, an ultra-performance liquid chromatography-electrospray ionization-mass spectrometer method was developed for the quantitative determination of the 13 marker constituents, homogentisic acid (1), 3,4-dihydroxybenzaldehyde (2), spinosin (3), liquiritin (4), baicalin (5), ginsenoside Rg1 (6), liquiritigenin (7), wogonoside (8), ginsenoside Rb1 (9), baicalein (10), glycyrrhizin (11), wogonin (12), and 6-gingerol (13) in Banhasasim-tang decoction. Separation of the compounds 1-13 was using an UPLC BEH $C_{18}$ ($100{\times}2.1mm$, $1.7{\mu}m$) column and column oven temperature was maintained at $45^{\circ}C$. The mobile phase consisted of 0.1% (v/v) formic acid in water (A) and acetonitrile (B) by gradient elution. The injection volume and flow rate were $2.0{\mu}L$ and 0.3 mL/min, respectively. Calibration curves of the compounds 1-13 were showed with $r^2$ values ${\geq}0.9908$. The limit of detection and limit of quantification values of the compounds 1-13 were 0.04-1.11 ng/mL and 0.13-3.33 ng/mL, respectively. Among the these compounds, the compounds 1-3 were not detected, while the compounds 4-13 were detected in the ranges of $3.20-107,062.98{\mu}g/g$ in Banhasasim-tang sample.

• YAKHAK HOEJI
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• v.60 no.2
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• pp.64-72
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• 2016

Jakyakgamcho-tang is a well-known traditional herbal medicine and has been used for the treatment of mainly pains in oriental medicine. In this study, analytical method for the quantitative determination of the eleven marker components, gallic acid (1), oxypaeoniflorin (2), paeoniflorin (3), albiflorin (4), liquiritin (5), isoliquiritin (6), ononin (7), liquiritigenin (8), benzoylpaeoniflorin (9), paeonol (10), and glycyrrhizin (11) in Jakyakgamcho-tang decoction was performed using an ultra-performance liquid chromatography-electrospray ionization-mass spectrometer. The analytical column for separation of the compounds 1~11 was used an UPLC BEH $C_{18}$ ($100{\times}2.1mm$, $1.7{\mu}m$) column and column oven temperature was maintained at $45^{\circ}C$. The mobile phase consisted of 0.1% (v/v) aqueous formic acid (A) and acetonitrile (B) by gradient elution. The flow rate was 0.3 ml/min and injection volume was $2.0{\mu}l$. Correlation coefficient in the calibration curves of the compounds 1~11 were showed a good linearity with more than 0.99. The limit of detection and limit of quantification values of the compounds 1~13 were detected in the ranges 0.06~18.43 ng/ml and 0.18~58.29 ng/ml, respectively. Among the compounds 1~11, the compounds 10 were not detected in this sample, while the ten compounds, 1~9 and 11, were detected $44.05{\sim}19,289.05{\mu}g/g$ in Jakyakgamcho-tang extract.

• Publications of The Korean Astronomical Society
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• v.30 no.3
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• pp.821-832
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• 2015

As a part of the short-period variability survey (SPVS) at Bohyunsan Optical Astronomy Observatory, we obtained time-series BV CCD images in the region of the open cluster NGC 1039 (M34). The observations were performed for 22 nights from July 29, 2008 to September 26, 2010. We also made LOAO observations for 10 days from September 18, 2009 to October 30, 2010 to confirm the small variabilties of ${\delta}$ Scuti-type variable stars. In this paper we presented the observational properties of 28 variable stars found in the region. They are seven ${\delta}$ Scuti-type variable stars, two ${\gamma}$ Doradus-type variable stars, four-teen eclipsing binary stars and five semi-long periodic or slow irregular variables, respectively. Only three variables were listed in the GCVS and the rest are newly discovered ones. We have performed multiple-frequency analysis to determine pulsation frequencies of the ${\delta}$ Scuti-type and ${\gamma}$ Doradus-type variable stars, using the discrete Fourier transform and linear least-square fitting methods. We also have derived the periods and amplitudes of 12 eclipsing binaries from the phase fitting method, and presented the light curves of all variable stars.