• Clinical and Experimental Reproductive Medicine
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• v.16 no.1
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• pp.69-79
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• 1989

Steroid hormone profiles during luteal phase of clomiphene citrate(CC)/human menopausal gonadotropin(hMG)/human chorionic gonadotropin(hCG)-stimulated in vitro fertilization (IVF) cycles and of follicle-stimulating hormone(FSH)/hMG/hCG-stimulated IVF cycles were compared. In seventy three cycles stimulated with CC/hMG/hCG regimen, follicles were aspirated during exploratory laparotomy and yielded 7 pregnancies, and in 83 cycles stimulated with FSH/hMG/hCG regimen, follicles were aspirated by laparoscope and made 13 pregnancies. Serum estradiol($E_2$) and progesterone($P_4$) levels were determined on days 2, 5, 7, and 9 after follicle aspiration. The FSH/hMG/hCG regimen was more effective than the CC/hMG/hCG regimen in folliculogenesis, ie, ovarian stimulation, follicular phase $E_2$ peak levels, oocyte maturation, and the number of retrieved oocytes. There was no significant difference between luteal serum $P_4/E_2$ ratio of the two regimens, suggesting that secretory endometrial build-up ability for implantation may not differ each other. Several significant correlations were observed between follicular phase seum $E_2$ peak levels and luteal phase serum $E_2$ and $P_4$ levels in the FSH/hMG/hCG-stimulated cycles but any correlation was not significant in the CC/hMG/hCG-stimulated cycles, suggesting that somewhat more follicles may eventually fall in atresia even after attaining dominant stage in the CC/hMG/hCG-stimulated cycles than the FSH/hMG/hCG-stimulated cycles.

• Korean Journal of Radiology
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• v.25 no.4
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• pp.384-394
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• 2024

Objective: To evaluate the image quality of novel dark-blood computed tomography angiography (CTA) imaging combined with deep learning reconstruction (DLR) compared to delayed-phase CTA images with hybrid iterative reconstruction (HIR), to visualize the cervical artery wall in patients with Takayasu arteritis (TAK). Materials and Methods: This prospective study continuously recruited 53 patients with TAK (mean age: 33.8 ± 10.2 years; 49 females) between January and July 2022 who underwent head-neck CTA scans. The arterial- and delayed-phase images were reconstructed using HIR and DLR. Subtracted images of the arterial-phase from the delayed-phase were then added to the original delayed-phase using a denoising filter to generate the final-dark-blood images. Qualitative image quality scores and quantitative parameters were obtained and compared among the three groups of images: Delayed-HIR, Dark-blood-HIR, and Dark-blood-DLR. Results: Compared to Delayed-HIR, Dark-blood-HIR images demonstrated higher qualitative scores in terms of vascular wall visualization and diagnostic confidence index (all P < 0.001). These qualitative scores further improved after applying DLR (Dark-blood-DLR compared to Dark-blood-HIR, all P < 0.001). Dark-blood DLR also showed higher scores for overall image noise than Dark-blood-HIR (P < 0.001). In the quantitative analysis, the contrast-to-noise ratio (CNR) values between the vessel wall and lumen for the bilateral common carotid arteries and brachiocephalic trunk were significantly higher on Dark-blood-HIR images than on Delayed-HIR images (all P < 0.05). The CNR values were significantly higher for Dark-blood-DLR than for Dark-blood-HIR in all cervical arteries (all P < 0.001). Conclusion: Compared with Delayed-HIR CTA, the dark-blood method combined with DLR improved CTA image quality and enhanced visualization of the cervical artery wall in patients with TAK.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.34 no.4C
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• pp.403-413
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• 2009

We compare three predistortion methods to prevent signal distortion and spectral re-growth due to the high PAPR (peak-to-average ratio) of OFDM signal and the non-linearity of high-power amplifiers. The three predistortion methods are pth order inverse, indirect learning architecture and look up table. The pth order inverse and indirect learning architecture methods requires less memory and has a fast convergence because these methods use a polynomial model that has a small number of coefficients. Nevertheless the convergence is fast due to the small number of coefficients and the simple computation that excludes manipulation of complex numbers by separate compensation for the magnitude and phase. The look up table method is easy to implement due to simple computation but has the disadvantage that large memory is required. Computer simulation result reveals that indirect learning architecture shows the best performance though the gain is less than 1 dB at $BER\;=\;10^{-4}$ for 64-QAM. The three predistorters are adaptive to the amplifier aging and environmental changes, and can be selected to the requirements for implementation.

• Bulletin of the Society of Naval Architects of Korea
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• v.14 no.1
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• pp.1-10
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• 1977

The major objects of this report are to supplement data of natural frequencies of thin elastic rectangular plates to the available data, and to give an experimental verification for natural frequencies obtained by Rayleigh-Ritz method, the generation set of which are eigenfunctions of Euler beams. For the first object the following five models, for which data only for the fundamental mode or data only for square plates are available, are adopted; (1) two opposed edges are clamped and the other two opposed edges simply supported (C-C, S-S), (2) one edge is simply supported and the other three edges clamped (C-C, C-S), (3) one edge is free and the other three edges clamped (C-C, C-F), (4) two adjacent edges are clamped and the other two adjacent edges free (C-F, C-F). For the (C-C, S-S) model the frequency equation obtained with the mode shapes assumed as of a single trigonometric series is solved. And for the other four models Rayleigh-Ritz method taking eigenfunctions of Euler beams as the generating set is applied. The numerical examples are obtained up to the fourth, the fifth or the sixth order depending on the range of the aspect ratio (0.1-10.0). The number of terms in the generating set for Rayleigh-Ritz method is fifteen for all models. For the experiment three models made of 3.2mm thickness mild steel plate for general structure use were prepared in following size; $300mm{\times}600mm,\;600mm{\times}600mm\;and\;900mm{\times}600mm$. Their boundary conditions are made to fit (C-C, C-F) condition. From the experiment mechanical impedance curves based on the frequency response method were obtained together with phase relation diagrams. The experimental data are resulted in good conformity to calculated values.

• Wind and Structures
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• v.28 no.1
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• pp.31-47
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• 2019

The accurate prediction of snow distributions under the wind action on roofs plays an important role in designing structures in civil engineering in regions with heavy snowfall. Affected by some factors such as building shapes, sizes and layouts, the snow drifting on roofs shows more three-dimensional characteristics. Thus, the research on three-dimensional snow distribution is needed. Firstly, four groups of stepped flat roofs are designed, of which the width-height ratio is 3, 4, 5 and 6. Silica sand with average radius of 0.1 mm is used to model the snow particles and then the wind tunnel test of snow drifting on stepped flat roofs is carried out. 3D scanning is used to obtain the snow distribution after the test is finished and the mean mass transport rate is calculated. Next, the wind velocity and duration is determined for numerical simulations based on similarity criteria. The adaptive-mesh method based on radial basis function (RBF) interpolation is used to simulate the dynamic change of snow phase boundary on lower roofs and then a time-marching analysis of steady snow drifting is conducted. The overall trend of numerical results are generally consistent with the wind tunnel tests and field measurements, which validate the accuracy of the numerical simulation. The combination between the wind tunnel test and CFD simulation for three-dimensional typical roofs can provide certain reference to the prediction of the distribution of snow loads on typical roofs.

• YAKHAK HOEJI
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• v.57 no.5
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• pp.330-336
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• 2013

"The Act on Medication Treatment of Sexual Impulse of Sex Offenders" known as chemical castration has been effective since July 2011 in Korea. According to the law, monitoring of male sex hormone in urine is enforced to request National Forensic Service more than once a month after injection of medicine designed to reduce sex impulse. We established a rapid and sensitive method for the monitoring of testosterone (T) and epitestosterone (E) in human urine by liquid chromatography with tandem mass spectrometry (LC-MS/MS). Three mL of urine was pretreated by solid-phase extraction for purification and performed enzymatic hydrolysis. The pretreated samples were extracted twice with 2 ml of ethyl acetate and n-hexane (2 : 3). The separation was applied on Thermo Hypersil GOLD C18 column ($1.9{\mu}m$, $100{\times}2.1mm$). A gradient elution of methanol and water of 0.1% formic acid were used as mobile phase and the retention time was less than 10 min. LC-MS/MS system coupled with an electrospray ionization source was performed in multiple reaction monitoring mode. The transitions of the analytes executed as following: m/z $289{\rightarrow}97$, 109 for T and E, m/z $292{\rightarrow}109$ for $T-d_3$ and $E-d_3$ as internal standards. The validation results of the method were satisfactory. The limits of detection were 0.05 ng/ml and the limits of quantification were 0.1 ng/ml. This method was successfully applied to real human urine sample. The developed method will be useful for monitoring T/E ratio in urine of sex offenders.

• Journal of the Korean Ceramic Society
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• v.32 no.2
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• pp.171-182
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• 1995

Five eucryptite and ten spodumene compositional powders were syntehsized from three sillimanite group, two kaolin group, and five pyrophyllite group silicate minerals. Those powders were isotatically pressed and fired at 1200~135$0^{\circ}C$ for 2 hrs, and then the sintered bodies were characterized. Silicate minerals with molar ratio of Al2O3 to SiO2 correspond to those of eucryptite and spodumene are kaolin and pyrophyllite group silicate minerals, respectively. Sintering characteristics of eucryptite from kaolin group and spodumene from pyrophyllite group mineral were superior to those from other silicate minerals. Eucryptite sintered bodies with 95~97% relative densities and densified microstructures can be obtained using Hadong pink kaolin as starting materials by sintering over broad temperature zone(1250~135$0^{\circ}C$). The eucryptite sintered bodies which were fired at 130$0^{\circ}C$ for 2hrs, from Hadong pink kaolin had within 3.0wt% microstructural compositional variations compaired with stoichiometric compound, and had good negative thermal expansiion property with -3.55$\times$10-6/$^{\circ}C$ thermal expansion coefficient. Spodumene sintered bodies which were prepared from pyrophyllite group silicate minerals, had dense microstructures and high densities by densification through liquid phase sintering with enlarged temperature range. The specimens which were fired at 130$0^{\circ}C$ for 2 hrs from Gusipyrophillite, had dense microstructure with crystallines mainly, and low thermal expansion property with 0.62$\times$10-6/$^{\circ}C$ thermal expansion coefficient. The porous texture and residual glass phase in LAS system ceramics which were prepared from silicate minerals, tend to increase the thermal expansion properties of sintered bodies to positive direction.

• Journal of Mechanical Science and Technology
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• v.16 no.12
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• pp.1693-1701
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• 2002

The intermittent spray characteristics of a multi-hole and a single-hole diesel nozzle were experimentally investigated. The hole number of the multi-hole nozzle was 5, and the hole diameter of the 5-hole and the single-hole nozzle was the same as d$\_$n/=0.32 ㎜ with the constant hole length to diameter ratio(l$\_$n//d$\_$n/=2.81). The droplet diameters of the spray, including the time-resolved droplet diameter, SMD (Sauter mean diameter) and AMD (arithmetic mean diameter) , injected intermittently from the two nozzles into the still ambient were measured by using a 2-D PDPA (phase Doppler particle analyzer). Through the time-resolved evolutions of the droplet diameter, it was found that the structure of the multi-hole and the single-hole nozzle spray consisted of the three main parts : (a) the leading edge affected by surrounding air. and composed of small droplets; (b) the central part surrounded by the leading edge and mixing flow region and scarcely affected by the resistance of air, (c) the trailing edge formed by the passage of the central part. The SMD decreases gradually with the increase in the radial distance, and the constant value is obtained at the outer region of the radial distance (normalized by hole diameter) of 7-8 and 6 for the 5-hole and single-hole nozzle, respectively. The SMD along the centerline of the spray decrease shapely with the increase in the axial distance after showing the maximum value near the nozzle tip. The SMD remains the constant value near the axial distance(normalized by hole diameter) of 150 and 180 for the 5-hole and the single-hole nozzle, respectively.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.36 no.2B
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• pp.176-183
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• 2011

In this paper, we propose the implementation and performance analysis of power line communication based on SISO/MIMO-OFDM which focuses on high speed data transmission in smart grid and future power line grid. We employ Zimmermann frequency model and Middleton Class A model as the multipath power line fading channel and impulse noise channel, respectively. In this paper, in order to improve the three-phase or single-phase PLC performance, we introduce a new MRC (called a&f-MRC) which effectively sums up multiple antenna diversity gain and multipath fading diversity gain. Via simulation, we prove the performance advantage over existing SISO/MIMO systems. In addition, we offer the tradeoff on system design through comparing with MRC, EGC and SC.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.48 no.5
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• pp.604-613
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• 2015

The objective of this study was to estimate the food quality of commercial boiled-dried Pacific herring Clupea pallasi as a substitute for boiled-dried anchovy. Standards for controlling quality of boiled-dried Pacific herring were suggested based on international (US FDA and CODEX) and domestic (Korean FDA, Standards on Quality of Seafood and Seafood Products, KS) standards for boiled-dried anchovy. The standards included requirements for moisture [less than 30% (less than 35 in very tiny sizes)], water activity (less than 0.85), salinity (less than 10%), water-phase salt (less than 20%), acid-insoluble ash (less than 1.5%), yeast and mold (fewer than 1.0×10³ CFU/g), and different size and breakage (less than 5%). Based on the standards suggested, commercial boiled-dried Pacific herring passed nine levels (all levels) in water activity, acid-insoluble ash, mold and yeast concentrations; seven levels (L-1, 2, 3, 4, M-1, 2, S) in water-phase salt, and three levels (L-1, 3, 4) in the ratio of different size and breakage categories. These results suggest that the quality of commercial boiled-dried Pacific herring is similar to that of commercial boiled-dried anchovy.