• Journal of Ginseng Research
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• v.32 no.4
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• pp.291-299
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• 2008

The fresh ginseng roots were extracted in aqueous methanol (MeOH), and the obtained extracts were partitioned using ethyl acetate (EtOA), n-butanol (n-BuOH), and water, successively. The repeated silica gel column chromatography for n-BuOH fraction afforded a purified ginsenoside $Rg_1$. The physico-chemical, spectroscopic and chromatographic data of ginsenoside $Rg_1$, such as crystallization characteristics, melting point, specific rotation, infrared spectrometry (IR) data, fast atom bombardment/mass spectrometry (FAB/MS) data, nuclear magnetic resonance (NMR) data, retention factor (Rf) in thin layer chromatography (TLC) experiment, and retention time (r.t.) in HPLC analysis, were measured and compared with those reported in literatures. Especially, the previous literatures reported different data for ginsenoside $Rg_1$ in the $^{1}H-$ and $^{13}C$-NMR experiments. This paper gives the exactly assigned NMR data through 2D-NMR experiments, such as $^{1}H-^{1}H$ correlation spectroscopy (COSY), hetero nuclear single quantum correlation (HSQC), and hetero nuclear multiple bond connectivity (HMBC).

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.31 no.6
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• pp.409-422
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• 2019

In this study, we carried out the 3D numerical simulation to investigate the hydraulic characteristics of Synchronous Edge wave known as the driving mechanism of beach cusp using the Tool Box called the ihFoam that has its roots on the OpenFoam. As a wave driver, RANS (Reynolds Averaged Navier-Stokes equation) and mass conservation equation are used. In doing so, we materialized short-crested waves known as the prerequisite for the formation of Synchronous Edge waves by generating two obliquely colliding Cnoidal waves. Numerical results show that as can be expected, flow velocity along the cross section where waves are focused are simulated to be much faster than the one along the cross section where waves are diverged. It is also shown that along the cross section where waves are focused, up-rush is moving much faster than its associated back-wash, but a duration period of up-rush is shortened, which complies the typical characteristics of nonlinear waves. On the other hand, due to the water-merging effect triggered by the redirected flow toward wave-diverging area at the pinacle of run-up, along the cross section where waves are diverged, offshore-ward velocity is larger than shore-ward velocity at the vicinity of shore-line, while at the very middle of shoaling process, the asymmetry of flow velocity leaned toward the shore is noticeably weakened. Considering that these flow characteristics can be found without exception in Synchronous Edge waves, the numerical simulation can be regarded to be successfully implemented. In doing so, new insight about how the boundary layer streaming occur are also developed.

• Journal of Environmental Science International
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• v.21 no.5
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• pp.585-596
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• 2012

This study is mainly focused on micellar effect of cetyltrimethyl ammonium bromide(CTABr) solution including alkylbenzimidazole(R-BI) on dephosphorylation of isopropyl-4-nitrophenylphosphinate(IPNPIN) in carbonate buffer(pH 10.7). The reactions of IPNPIN with R-$BI^{\ominus}$ are strongly catalyzed by the micelles of CTABr. Dephosphorylation of IPNPIN is accelerated by $BI^{\ominus}$ ion in $10^{-2}$ M carbonate buffer(pH 10.7) of $4{\times}10^{-3}$ M CTABr solution up to 89 times as compared with the reaction in carbonate buffer by no benzimidazole(BI) solution of $4{\times}10^{-3}$ M CTABr. The value of pseudo first order rate constant($k_{\Psi}$) of the reaction in CTABr solution reached a maximum rate constant increasing micelle concentration. Such rate maxima are typical of micellar catalyzed bimolecular reactions. The reaction mediated by R-$BI^{\ominus}$ in micellar solutions are obviously slower than those by $BI^{\ominus}$, and the reaction rate were decreased with increase of lengths of alkyl groups. It seems due to steric effect of alkyl groups of R-$BI^{\ominus}$ in Stern layer of micellar solution. The surfactant reagent, CTABr, strongly catalyzes the reaction of IPNPIN with R-BI and its anion(R-$BI^{\ominus}$) in carbonate buffer(pH 10.7). For example, $4{\times}10^{-3}$ M CTABr in $1{\times}10^{-4}$ M BI solution increase the rate constant($k_{\Psi}=98.5{\times}10^{-3}\;sec^{-1}$) of the dephosphorylation by a factor ca.25, when compared with reaction($k_{\Psi}=3.9{\times}10^{-4}\;sec^{-1}$) in $1{\times}10^{-4}$ M BI solution(without CTABr). And no CTABr solution, in $1{\times}10^{-4}$ M BI solution increase the rate constant($k_{\Psi}=3.9{\times}10^{-4}\;sec^{-1}$) of the dephosphorylation by a factor ca.39, when compared with reaction ($k_{\Psi}=1.0{\times}10^{-5}\;sec^{-1}$) in water solution(without BI). This predicts that the reactivities of R-$BI^{\ominus}$ in the micellar pseudophase are much smaller than that of $BI^{\ominus}$. Due to the hydrophobicity and steric effect of alkyl group substituents, these groups would penetrate into the core of the micelle for stabilization by van der Waals interaction with long alkyl groups of CTABr.

• Proceedings of the Korean Geotechical Society Conference
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• 2001.03a
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• pp.167-174
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• 2001

Reflection method using ultrasonic source has been attempted to obtain the information about tunnel lining structures composed of lining, shotcrete, water barrier and voids at the back of lining. In this work, two different types of sources, i.e. single-pulse source and sweep source, can be used. Single-pulse source with short time duration has the frequency content whose amplitudes tend to be concentrated around the dominant frequency, whereas sweep source with long time duration denotes a flat distribution of relatively larger amplitude over a broad frequency band, although the peak to peak amplitude of single-pulse source wavelet is equivalent to that of sweep source one. In traditional seismic application, a single-pulse source(weight drop, dynamite) is typically used. However, to investigate the fine structure, as it is the case in the tunnel lining structure, the sweep wavelet can be also a desirable source waveform primarily due to the higher energy over a broad frequency band. For the investigation purposes of sweep source, a physical modeling is a useful tool, especially to study problems of wave propagation in the fine layered media. The main purpose of this work was using a physical modeling technique to explore the applicability of sweep source to the delineation of inner layer boundaries. To this end, a two-dimensional physical model analogous to the lining structure was built and a special ultrasonic sweep source was devised. The measurements were carried out in the sweep frequency range 10 ∼ 60 KHz, as peformed in the regular reflection survey(e.g. roll-along technique). The measured data were further rearranged with a proper software (cross-correlation). The resulting seismograms(raw data) showed quitely similar features to those from a single-pulse source, in which high frequency content of reflection events could be considerably emphasized, as expected. The data were further processed by using a regular data processing system "FOCUS" and the results(stack section) were well associated with the known model structure. In this context, it is worthy to note that in view of measuring condition the sweep source would be applied to benefit the penetration of high frequency energy into the media and to enhance the resolution of reflection events.

• The Journal of Korean Academy of Prosthodontics
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• v.43 no.4
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• pp.562-572
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• 2005

Statement of problem : Titanium is widely used as an implant material lot artificial teeth. Also, studies on surface treatment to form a fine passive film on the surface of commercial titanium or its alloys and improving bioactivity with bone have been carried out. However, there is insufficient data about the biocompatibility of the implant materials in the body. Purpose: The purpose of this study was to examine whether the precipitation of apatite on titanium metal is affected by surface modification. Materials and methods: Specimens chemically washed for 2 minute in a 1:1:1.5 (in vol%) mixture of 48% HF 60% $HNO_3$ and distilled water. Specimens were then chemically treated with a solution containing 97% $H_2SO_4$ and 30% $H_2O_2$ at $40^{\circ}C$S for 1 hour, and subsequently heat-treated at $400^{\circ}C$ for 1 hour. All specimens were immersed in the HBSS with pH 7.4 at $36.5^{\circ}C$ for 15 days, and the surface were examined with TF-XRD, SEM, EDX and XPS. Also, commercial purity Ti specimens with and without surface treatment were implanted in the abdominal connective tissue of mice for 4 weeks. Conventional aluminium and stainless steel 316L were also implanted for comparison. Results and conclusions : The results obtained were summarized as follows. 1. An amorphous titania gel layer was formed on the titanium surface after the titanium specimen was treated with a $H_2SO_4$ and $H_2O_2$ solution. The average roughness was $2.175{\mu}m$ after chemical surface treatment. 2. The amorphous titania was subsequently transformed into anatase by heat treatment at $400^{\circ}C$ for 1 hour. 3. The average thickness of the fibrous capsule surrounding the specimens implanted in the connective tissue was $46.98{\mu}m$ in chemically-treated Ti, and 52.20, 168.65 and $100.95{\mu}m$ respectively in commercial pure Ti, aluminum and stainless steel 316L without any treatment.

• Journal of the korean academy of Pediatric Dentistry
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• v.27 no.2
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• pp.370-378
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• 2000

The composite restorative resins have their insufficient resistance to wear. The subsurface degradation within the restoration is considered to be associated with wear. The aim of this study was to evaluate the resistance to degradation of six commercial composite resins in an alkaline solution. The brands studied were Clearfil APX(Kuraray), Heliomolar(Vivadent), Surefil(Dentsply), TPH(Dentsply), Tetric Ceram(Vivadent), and Z100(3M). Preweighed discs of each brand were exposed 0.1N NaOH solution at $60^{\circ}C$. After 14 days they were removed, neutralized with HCL, washed with water and dried to constant mass at $60^{\circ}C$. Resistance to degradation was evaluated on the basis of the following parameters: (a) mass loss(%) - determined from pre-and post-exposure specimen weights; (b) Si loss (ppm)-obtained from ICP-AE analysis of solution exposed to specimens; and (c) degradation depth$({\mu}m)$ - measured microscopically (SEM) from polished circular sections of exposed specimens. The results were as follows: 1. The mass loss was in descending order by Z100, TC H, S, CL, TPH and in the range of $0.45\sim3.64%$ 2. The degradation layer depth was in descending order by H, Z100, S, TC, TPH, CL and in the range of $10.85\sim73.38{\mu}m$ 3. For the Si concentration, Z100 was the highest of all 4. The highly significant correlation(r=0.81, p<0.05) was observed between mass loss and degradation depth. 5. Under scanning electronmicroscopy, the degradation of connection between resin matrix and fillers was observed 2 weeks after soaking in NaOH solution.

• Progress in Medical Physics
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• v.9 no.4
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• pp.259-266
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• 1998

To achieve the 2D dose distribution around the designed high dose rate Ir-192 source substitution for Co-60 brachytherapy source, we determined the exposure rate constant and tissue attenuation factors as a large depth as a 20 cm from source center. The exposure rate constant is used for apparent activity in designed source with self-absorption and encapsulation steel wall. The tissue dose delivered from the 4401 segments of 2.5 mm in a diameter and 2.5 mm height of disk-type source layer. In the experiments, the tissue attenuation factors include the tissue attenuation and multiple scattering in a medium surrounding the source. The fitted the polynomial regression with 4th order for the tissue attenuation factors are very closed to the experimental measurement data within ${\pm}$1% discrepancy. The Meisberger's constant showed the large uncertainty in large distance from source. The exposure rate constant 4.69 Rcm$^2$/mCi-hr was currently used for determination of apparent activity of source and air kerma strength was obtained 0.973 for tissue absorbed dose from the energy spectrum of Ir-192 source. In our experiments with designed high dose rate brachytherapy source, the apparent activity of Ir-192 source was delivered from the 54.6 % of actual physical source activity through the self-absorption and encapsulation wall attenuations. This paper provides the 2-dimensional dose tabulation from unit apparent activity in a water medium for dose planning includes the multiple scattering, source anisotropy effect and geometric factors.

• Membrane Journal
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• v.29 no.6
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• pp.339-347
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• 2019

Forward osmosis (FO) is operated at a lower pressure than reverse osmosis (RO), which has great advantages in terms of fouling control, maintenance, membrane cleaning, and potential energy reduction. In particular, since the membrane fouling layer of the forward osmosis process has a relatively loose and dispersed property, it is possible to control the membrane fouling by physical cleaning, unlike the reverse osmosis process. However, existing studies do not apply the proper cleaning flow rate for forward osmosis physical cleaning, and thus there is a limit that the optimal operation can not be performed. Therefore, this study aims to evaluate the justification of proper flow rate that can show high efficiency cleaning with economical energy amount. The membrane fouling experiments of the forward osmosis process were maintained at a circulating flow rate of 8.54 cm/s and the recovery rates were compared with the three cleaning flow rates. As a result of this experiment, it was confirmed that the 2 × speed cleaning showed the same efficiency as the water permeability recovery rate of the 3 × speed cleaning, and it was confirmed that the 2 × speed cleaning was an appropriate flow rate with high cleaning efficiency and economical SEC.

• Korean Chemical Engineering Research
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• v.45 no.5
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• pp.500-505
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• 2007

The objectives of this research were to (1) identify the membrane fouling potential due to different fractions of NOM (2) correlate the physicochemical properties of NOM and membranes with the adsorption of humic substances on membrane (4) find out the effect of membrane physical and chemical washing according to membrane material. The static adsorption test and adsorption test showed that hydrophobic organics adsorbed much more quickly than hydrophilic organics. In case of the effect of membrane properties on the adsorption of organic fractions, the adsorption rate ratio(a) of hydrophobic membrane (0.016, 0.077) was greater than that of hydrophilic membrane (0.010, 0.033) regardless of the kind of organic fractions. This suggests that the UF membrane fouling were occurred mainly by internal pore size decreasing due to adsorption of organic into pore surface for hydrophobic membrane, and by sieving of organics and forming a gel layer on the membrane surface for hydrophilic membrane. In conclusion, the decrease in the pore volume, which was caused by the organic adsorption into the internal pore, was greater with the hydrophobic membrane than with the hydrophilic membrane. In case of the effect of membrane properties on permeate flux, the rate of flux decline for the hydrophobic membrane was significantly greater than that for the hydrophilic membrane.

• Journal of the Korean Institute of Traditional Landscape Architecture
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• v.32 no.3
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• pp.21-31
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• 2014

This study aims to comparison of spatial composition that Okhojeong garden and Seokpajeong garden. Construct background and space structure in both of Okhojeong garden and Seokpajeong garden is analyzed. The results were as follows. First, Okhojeong garden and Seokpajeong garden of the nobles gardens in late Joseon dynasty. They had the advanced techniques of contemporary based on their political power and wealth, and therefore could built garden and enjoy the garden culture of the upper layer. Furthermore, composition of the Okhojeong garden can be assumed that it is related to construction of the Seokpajeong garden through analysis of the relationship between builders. Secondly, Space structure of Okhojeong garden and Seokpajeong garden is divided into pavilion unit of small gardens with living space as the center. Construction pavilion in each garden space imbues certain landscape theme. In addition, authorization of characteristics of a place in each area is attempted through boundary establishment and selective garden culture of varied seasonal landscape. Thirdly, In Seokpajeong garden, most of construction characteristics of Okhojeong garden are appeared. This indicates that Seokpajeong garden was affected by space-configuration-technique of Okhojeong garden such as acceptation or modification recreation. Fourth, In many cases, fanciers regarding floriculture are expanded to enthusiasts in late Joseon dynasty. In Okhojeong garden and Seokpajeong garden, herbaceous ornamental is considered to be precious and garden materials such as water tray, stone couch, oddly shaped stone, potted plant, artificial hill, wisteria trellis are diversified at the time.