• Korean Journal of Applied Biomechanics
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• v.27 no.1
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• pp.9-18
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• 2017

Objective: The purpose of this study was to identify kinematic variables that govern successful performance and judges' scores and to establish correlative relationships among those of Yurchenko layout with a full twist in female vaults. Method: Four video cameras with sampling rate of 60 Hz collected 32 motion data of Yurchenko vaults from twenty-two female participants (age: $18.6{\pm}3.6years$, height: $153.0{\pm}6.5cm$, mass: $44.7{\pm}7.3kg$) during national competition. Posting processing and calculations of kinematic variables were performed in Kwon 3D XP and $Matlab^{(R)}$ programs. Correlation and regression analyses were applied to find the relationships between the obtained scores and kinematic variables. Deterministic model (Hay & Reid, 1988) was used to investigate the strength of correlative relationships among kinematic variables. Results: The obtained scores from the judges' decision were mainly affected by post-flight peak height, horse contact time, knee angle at landing, and horse takeoff angle. Strong blocking during horse contact was required to get successful performance and obtain high scores. Modified deterministic model showed that round-off entrance and takeoff angles and resultant velocity of the center of mass (CM) during the roundoff phase were the starting variables affecting performance in the following kinematics. Knee angle at landing, a highly influential variable on the obtained point, was only determined by judges' decision without significant correlative relationship with previous kinematic variables. Conclusion: The obtained scores highly depended on kinematic variables of post-flight and horse contact phases that were affected by those from the previous phases including round-off postures and resultant velocity of the body center of mass.

• Korean Journal of Pharmacognosy
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• v.43 no.2
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• pp.137-146
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• 2012

Dipsaci Radix (Dipsacaceae) has been used as a tonic, an analgesic, anti-inflammatory and anti-complement agents in traditional herbal medicine for the therapy of low back pain, knee pain, rheumatic arthritis, traumatic hematoma, and bone fractures. A high-performance liquid chromatography-electrospray ionization-mass spectrometric method (HPLC-ESI-MS) was developed for the simultaneous quantitation method of the five compounds from the herbal drug: asperosaponin VI and asperosaponin XII (terpene glycosides), sweroside, loganin and dipsacus A(iridoid glycosides). HPLC separation of the analytes was achieved on a C18 column ($150{\times}2.0$ mm i.d., 5 ${\mu}m$) using the aqueous methanol containing 5 mM ammonium acetate with gradient flow of the mobile phase. Detection of the analytes was performed by positive ion electrospray ionization, and selected ion monitoring was used for data acquisition using m/z corresponding molecular adduct ion, $[M+NH_4]^+$ and $[M+H]^+$. Calibration graphs showed good linearity ($r^2$=0.9997) over the wide range of the analytes; intra- and inter-day precisions (RSD, %) were within 9.1% and the accuracy between 94.0-111.0%. Recoveries of the analytes through the assay procedure were in the range of 93.7-110.8%. Analytical results of the herbal drugs of Dipsaci Radix (17 samples) show wide distribution of the five marker compounds and clear difference of the species from Phlomidis Radix (4 samples). The developed method would provide a practical guide for the quality control of the herbal drug.

• Applied Chemistry for Engineering
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• v.8 no.2
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• pp.220-229
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• 1997

Extraction of valuable light hydrocarbon from atmospheric residue using pentane as a solvent has been carried out. The SIMDIS was used to calculate the true boiling point of atmospheric residue containing complex components before the modeling of the extraction process could by performed. In order to simplify the procedure, modeling was adopted and a lumping method was used, such that a large number of compounds were divided into similar component classes called pseudocomponents. The modeling of the extraction process of the atmospheric residue-pentane system was based on the isothermal flash calculation, and the Peng-Robinson equation of state was used to calculate the fugacity coefficient of vapor and liquid phase during calculation steps of modeling. The agreement between the experiments and the calculations was reasonable considering the uncertainties involved in modeling such complex processes.

• Journal of the Korean Society for Nondestructive Testing
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• v.20 no.5
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• pp.438-444
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• 2000

The prediction of mechanical properties for WC-Co alloys by evaluation of coercive force and magnetic saturation were studied in relation to their microstructure. The WC-8%Co alloys were prepared using different WC particle size, carbon content and various sintering temperature by PM process. The magnetic properties such as coercive force and magnetic saturation of sintered WC-Co alloys were critically dependent upon their final composition and microstructure. Slight changes of carbon contents and small variation of WC grain size result in marked changes of magnetic properties, hardness and transverse rupture strength of sintered WC-Co alloys. It was found that the coercive force and hardness were increased by fine WC grain size of sinterd alloys, and the coercive force was proportional to hardness. With decreasing total carbon content below the stoichiometric value in WC-8%Co alloys the volume fraction of $\eta$ phase increased steadily, while the magnetic saturation and transverse rupture strength decreased. The magnetic saturation was inversely proportional to the coercive force of WC-Co alloys.

• Natural Product Sciences
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• v.17 no.2
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• pp.147-159
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• 2011

A high-performance liquid chromatography-electrospray ionization-tandem mass spectrometric method was developed to determine simultaneously eight marker constituents of Forsythiae fructus, and subsequently applied it to classify its two botanical origins. The marker compounds of Forsythia suspensa were phillyrin, pinoresinol, phillygenin, lariciresinol and forsythiaside; those of F.viridissima were arctiin, arctigenin and matairesinol. Separation of the eight analytes was achieved on a phenyl-hexyl column (150${\times}$2.0 mm i.d., 3 ${\mu}M$) using gradient elution with the mobile phase: (A) 10% acetonitrile in 0.5% acetic acid, (B) 40% aqueous acetonitrile. A few fragment ions specific to the types of lignans, among the product ions generated by collisonally induced dissociation (CID) of molecular ion clusters, such as [M-H]$^-$ or [M+OAc]$^-$ were used not only for fingerprinting analysis but for the quantification of each epimer by using multiple-reaction monitoring mode. It was shown good linearity ($r^2{\geq}$ 0.9998) over the wide range of all analytes; intra- and inter-day precisions (RSD, %) were within 9.14% and the accuracy ranged from 84.3 to 115.1%. The analytical results of 40 drug samples, combined with multivariate statistical analyses - principal component analysis (PCA) and hierarchical cluster analysis (HCA) - clearly demonstrated the classification of the test samples according to their botanical origins. This method would provide a practical strategy for assessing the authenticity or quality of the herbal drug.

• Korean Journal of Pharmacognosy
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• v.47 no.1
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• pp.79-83
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• 2016

This study developed an HPLC analysis method for the determination of isoegomaketone (IK) and perillaketone (PK) in Perilla frutescens (L.) Britton leaves. P. frutescens ethanol extract was optimized through an HPLC analysis using a C18 column ($250{\times}4.6mml$, D, $S-5{\mu}m$, 12 nm) with gradient elution of water and acetonitrile as the mobile phase at a flow rate of 1 mL/min and a UV detection wavelength of 254 nm. The results of this method showed linearity in the calibration curve at a coefficient of correlation ($R^2$) of IK 0.9995, PK 0.9998. The limits of detection (LOD) for IK and PK were $0.234{\mu}g/mL$ and $0.952{\mu}g/mL$. The limits of quantification (LOQ) for IK and PK were $0.017{\mu}g/mL$ and $0.043{\mu}g/mL$. The inter-day precision RSDs of IK and PK in the P. frutescens were 1.25 to 2.69% and 0.36 to 1.10%, respectively, and the intra-day precision RSDs of IK and PK were 0.96 to 2.51% and 0.90 to 1.93%, respectively. The accuracies of IK and PK were 96.31 to 97.92% and 101.26 to 105.14%. In conclusion, this method was applied successfully to the detection of IK and PK in P. frutescens.

• Biomolecules & Therapeutics
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• v.26 no.5
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• pp.494-502
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• 2018

Breast cancer is currently the most prevalent cancer in women, and its incidence increases every year. Azole antifungal drugs were recently found to have antitumor efficacy in several cancer types. They contain an imidazole (clotrimazole and ketoconazole) or a triazole (fluconazole and itraconazole) ring. Using human breast adenocarcinoma cells (MCF-7 and MDA-MB-231), we evaluated the effects of azole drugs on cell proliferation, apoptosis, cell cycle, migration, and invasion, and investigated the underlying mechanisms. Clotrimazole and ketoconazole inhibited the proliferation of both cell lines while fluconazole and itraconazole did not. In addition, clotrimazole and ketoconazole inhibited the motility of MDA-MB-231 cells and induced $G_1$-phase arrest in MCF-7 and MDA-MB-231 cells, as determined by cell cycle analysis and immunoblot data. Moreover, Transwell invasion and gelatin zymography assays revealed that clotrimazole and ketoconazole suppressed invasiveness through the inhibition of matrix metalloproteinase 9 in MDA-MB-231 cells, although no significant changes in invasiveness were observed in MCF-7 cells. There were no significant changes in any of the observed parameters with fluconazole or itraconazole treatment in either breast cancer cell line. Taken together, imidazole antifungal drugs showed strong antitumor activity in breast cancer cells through induction of apoptosis and $G_1$ arrest in both MCF-7 and MDA-MB-231 cells and suppression of invasiveness via matrix metalloproteinase 9 inhibition in MDA-MB-231 cells. Imidazole drugs have well-established pharmacokinetic profiles and known toxicity, which can make these generic drugs strong candidates for repositioning as antitumor therapies.

• International Journal of Control, Automation, and Systems
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• v.6 no.4
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• pp.534-543
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• 2008

To use the Global Positioning System (GPS) carrier phase measurement for precise positioning, the integer ambiguities at the early stage of most algorithms must be determined. Furthermore, if a precise positioning is to be applied to real time navigation, fast determination and validation methods for integer ambiguity are essential. In this paper, the Wald test that simultaneously determines and validates integer ambiguities is used with assistance of the Inertial Navigation System (INS) to improve its performance. As the Wald test proceeds, it assigns a higher probability to the candidate that is considered to be true at each time step. The INS information is added during the Wald test process. Large performance improvements were achieved in convergence time as well as in requiring fewer observable GPS satellites. To test the performance improvement of the Wald test with the INS information, experimental tests were conducted using a ground vehicle. The vehicle moved in a prescribed trajectory and observed seven GPS satellites. To verify the effect of the INS information on the Wald test, the convergence times were compared with cases that considered the INS information and cases that did not consider the INS information. The results show that the benefits of using the INS were emphasized as fewer GPS satellites were observable. The performance improvement obtained by the proposed algorithm was shown through the fast convergence to the true hypothesis when using the INS measurements.

• Journal of the Korean Ceramic Society
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• v.32 no.12
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• pp.1392-1400
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• 1995

WC-10wt%Co-Al2O3 ceramic composites, using both the SHS (Self-propagating High Temperature Synthesis) synthesized WC powder method and commercial WC powder, were prepared by varing WC-Co/Al2O3 vol% ratio and sintering temperature (1350℃∼1650℃) for 1 hr in Ar atmosphere. Mechanical characterization has been investigated by Instron meterial testing system and Vicker's hardness test. Compositional and structural chracterizations were carried out by energy-dispersive analysis of X-ray (EDAX) data and scanning electron microscope (SEM). Electrical characterization was carried out by the electrical resistivity measurement using 4-point probe method. As sintering period increased and Al2O3 contents decreased in WC-10wt%Co-Al2O3 ceramic composite, shrinkage and relative density increased, resulting in maximum values at 1600℃. Also the major matrix phase changed with increasing Al2O3 content from 0 to 100 vol%. It was also identified by SEM, EDAX, and electrical resistivity measurement. Based on the results of analysis of flexural strength, toughness and hardness, the mechanical properties of WC-10wt%Co-Al2O3 ceramic composites using the SHS synthesized WC powder were better than those WC-10wt%Co-Al2O3 ceramic composites using commercial WC powder because WC-10wt%Co-Al2O3 ceramic composites using the SHS synthesized WC powder were sintered very well due to small initial particle size. By the addition of 40 vol% Al2O3 [60(WC=10wt%Co)-40Al2O3], it was possible to obtain a proper candidate as a superalloy.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.30 no.3
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• pp.165-173
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• 2007

A space launch vehicle system represents a typical example of large-scale multi-disciplinary systems, consisting of subsystems such as mechanical structure, electronics, control, telecommunication, propulsion, material engineering etc. A lot of cost is required to develop the launch vehicle system. A precise planning of R&D cost is very essential to make a success of the launch vehicle development program. Especially in the early development phase of a new space launch vehicle system, cost estimation techniques and analogy from past similar development data are very useful methods to estimate a development cost of the launch vehicle system. Now Korea Aerospace Research Institute is in charge of the KSLV-I (Korea Space Launch Vehicle-I) Program that is a part of Korea National Space program. KSLV-I Program is a national undertaking to develop launch capabilities to deliver science satellites of a 100kg-class into a low earth orbit. It is hereafter, going to plan to develop a new korean space launch vehicle. In this paper, first the development costs of well-known launch vehicles in the world are presented to provide a reference to make a development plan of a new launch vehicle. Second this paper introduces the present status of cost estimation applications at NASA. Finally this paper presents the results from application of a TRANSCOST, a parametric cost model, to derive a cost estimate of a new launch vehicle development, as an example.