• Clinical and Experimental Reproductive Medicine
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• v.26 no.2
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• pp.239-249
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• 1999

The role of amino acids in culture media for IVF-ET was examined in a total of 76 cycles. Patients received clomiphene citrate (CC) followed by hMG or GnRH-a combined with gonadotropins (FSH/hMG) for controlled ovarian hyperstimulation. Severe male (<$4{\times}10^6$ motile sperm) or age factor (>39 y) patients were excluded in this study. Pregnancy was classified as clinical if a gestational sac or fetal cardiac activity was seen on ultrasound. No significant differences were found in age, duration of infertility, follicle size, the level of $E_2$ on the day of hCG injection, the mean number of oocytes retrieved, total motile sperm count, fertilization rate and the mean number of embryos transferred between bHTF (without amino acids) and mHTF (with amino acids) groups. However, total ampules of gonadotropins were higher (p<0.01) in mHTF group than bHTF group. Significantly (p<0.05) more clinical pregnancies were recorded in mHTF group (13/30) compared with bHTF group (9/46). The multiple pregnancy rates were 11.1% in bHTF group and 7.7% in mHTF group. There were one ectopic pregnancy in mHTF group and one heterotopic pregnancy in bHTF group. Abortion rates were 22.2% in bHTF group and 7.7% in mHTF, respectively. The ongoing pregnancy or livebirth rate was significantly (p<0.05) higher in mHTF group (12/30) than bHTF group (7/46). These results suggest that the addition of amino acids in culture media is essential for culture of zygotes in vitro and adjustment of energy substrates in phosphate-free culture media appears to be beneficial for human IVF-ET procedure.

• Journal of electromagnetic engineering and science
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• v.1 no.1
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• pp.73-77
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• 2001

We studied the fabrication of GaAs-based pseudomorphic high electron mobility transistors(PHEMT`s) for the purpose of millimeter- wave applications. To fabricate the high performance GaAs-based PHEMT`s, we performed the simulation to analyze the designed epitaxial-structures. Each unit processes, such as 0.1 m$\mu$$\Gamma$-gate lithography, silicon nitride passivation and air-bridge process were developed to achieve high performance device characteristics. The DC characteristics of the PHEMT`s were measured at a 70 $\mu$m unit gate width of 2 gate fingers, and showed a good pinch-off property ($V_p$= -1.75 V) and a drain-source saturation current density ($I_{dss}$) of 450 mA/mm. Maximum extrinsic transconductance $(g_m)$ was 363.6 mS/mm at $V_{gs}$ = -0.7 V, $V_{ds}$ = 1.5 V, and $I_{ds}$ =0.5 $I_{dss}$. The RF measurements were performed in the frequency range of 1.0~50 GHz. For this measurement, the drain and gate voltage were 1.5 V and -0.7 V, respectively. At 50 GHz, 9.2 dB of maximum stable gain (MSG) and 3.2 dB of $S_{21}$ gain were obtained, respectively. A current gain cut-off frequency $(f_T)$ of 106 GHz and a maximum frequency of oscillation $(f_{max})$ of 160 GHz were achieved from the fabricated PHEMT\\`s of 0.1 m$\mu$ gate length.h.

• Imaging Science in Dentistry
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• v.33 no.2
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• pp.113-119
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• 2003

Purpose : To evaluate the relationship between morphometric analysis of bone microstructure from digital radiographic image and trabecular bone strength. Materials and Methods : One hundred eleven bone specimens with 5 mm thickness were obtained from the mandibles of 5 pigs. Digital images of specimens were taken using a direct digital intraoral radiographic system. After selection of ROI (100 × 100 pixel) within the trabecular bone, mean gray level and standard deviation were obtained. Fractal dimension and the variants of morphometric analysis (trabecular area, periphery, length of skeletonized trabeculae, number of terminal point, number of branch point) were obtained from ROI. Punch sheer strength analysis was performed using Instron (model 4465, Instron Corp., USA). The loading force (loading speed 1 mm/min) was applied to ROI of bone specimen by a 2 mm diameter punch. Stress-deformation curve was obtained from the punch sheer strength analysis and maximum stress, yield stress, Young's modulus were measured. Results: Maximum stress had a negative linear correlation with mean gray level and fractal dimension significantly (p<0.05). Yield stress had a negative linear correlation with mean gray level, periphery, fractal dimension and the length of skeletonized trabeculae significantly (p < 0.05). Young's modulus had a negative linear correlation with mean gray level and fractal dimension significantly (p < 0.05). Conclusions : The strength of cancellous bone exhibited a significantly linear relationship between mean gray level, fractal dimension and morphometric analysis. The methods described above can be easily used to evaluate bone quality clinically.

• Imaging Science in Dentistry
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• v.39 no.3
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• pp.163-168
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• 2009

Purpose : To assess the clinical findings and hard tissue changes of osteomyelitis of the jaws using computed tomographic (CT) image analysis. Materials and Methods : We reviewed and interpreted the CT images of 163 patients (64 males and 99 females, age range from 10 to 87 years) who visited the Seoul National University Dental Hospital from April 23, 2006 to December 31, 2008 and were diagnosed as osteomyelitis of the jaws through clinical, radiologic, and histopathologic examination. Each CT findings was investigated for frequency, correlation with age and gender. Results : Of the 163 patients, 31 (19.0%) were affected on the maxilla, 135 (82.8%) were affected on the mandible, and 3 (1.8%) were affected on the both jaws simultaneously. The mean age of the patients who were affected on the maxilla was 61.0 years and that of the patients who were affected on the mandible was 56.2 years. On the maxilla, the most frequent site of disease was the posterior area (83.9%) and on the mandible, mandibular body (83.0%), followed by angle (48.1%), ramus (38.5%), condyle (13.3%), incisal area (9.6%), and coronoid process (3.0%). Among the 31 maxillary osteomyelitis, defect in the trabecular bone was observed in 28 (90.3%), osteosclerosis 20 (64.5%), defect in the cortical bone 27 (87.1%), sequestrum 17 (54.8%), and periosteal reaction 2 (6.5%). Among the 135 mandibular osteomyelitis, defect in the trabecular bone was observed in 100 (74.1%), osteosclerosis 104 (77.0%), defect in the cortical bone 116 (85.9%), sequestrum 36 (26.7%), and periosteal reaction 67 (49.6%). Conclusion : Of our cases, the maxillary osteomyelitis was visibly observed more frequently in females than males. The incidence is the highest in seventies (28.8%) and the lowest in teens (3.1%). The osteomyelitis of the jaws was observed more frequently in males than females before the age of 50, and observed more frequently in females after the age of 50. The most noticeable point was that the sequestrum was observed more often on maxillary osteomyelitis and the periosteal reaction was observed more often on mandibular osteomyelitis.

• Journal of the Korean Geotechnical Society
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• v.21 no.5
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• pp.83-92
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• 2005

The aim of this study was to investigate damage conditions of cut slope structures due to acid rock drainage (ARB) and to assess the acid production potential of various rocks. Acid rock drainage is produced by the oxidation of sulfide minerals contained in coal mine zone and mineralization belt of Pyeongan supergroup and Ogcheon group, pyrite-bearing andesite, and Tertiary acid sulfate soils in Korea. Most of cut slopes producing ARB have been treated with shotcrete to reduce ARD. According to the field observations, ARD had an adverse effect on slope structures. The corrosion of shotcrete, anchors and rock bolts and the bad germination and growth diseases of covering plants due to ARD were observed in the field. The concentration of heavy metals and pH of ARD from cut slope exceeded the environmental standard, indicating a high potential of environmental pollution of surrounding soil, surface water and ground water by the ARD. According to acid base accounting (ABA) of the studied samples, hydrothermally altered volcanic rocks, tuffs, coaly shales, tailings of metallic mine had a relatively high potential of acid production but gneiss and granite had no or less acid production potential. It is expected that the number of cut slopes will increase hereafter considering the present construction trend. In order to reduce the adverse effect of ARD in construction sites, we need to secure the data base for potential ARD producing area and to develop the ARD reduction technologies suitable.

• Corrosion Science and Technology
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• v.13 no.3
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• pp.95-101
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• 2014

The pitting corrosion behaviors between the constituent phases in F53 super duplex stainless steel (SDSS) in acidified chloride environments were investigated using a critical pitting corrosion temperature test, a potentiodynamic anodic polarization test, and the microstructure analyses through a SEM-EDS and a SAM. As the solution annealing temperature decreased from $1150^{\circ}C$ to $1050^{\circ}C$, the ${\gamma}$-phase fraction increased whereas the ${\alpha}$-phase fraction decreased. The pitting potential and the critical pitting temperature increased with a decrease of solution annealing temperature, thereby increasing the resistance to pitting corrosion. The pitting corrosion of the SDSS was selectively initiated at the ${\alpha}$-phases because the PREN (pitting resistance equivalent number, PREN = %Cr+3.3%Mo+30%N) value of the ${\gamma}$-phase is much larger than that of the ${\alpha}$-phase, irrespective of the solution annealing temperature. The pitting corrosion was finally propagated from the ${\alpha}$-phase to the ${\gamma}$-phase. The decrease of solution annealing temperature enhanced the resistance to pitting corrosion greatly in acidified chloride environments due to a decrease of PREN difference between the ${\gamma}$-phase and the ${\alpha}$-phase, that is, a decrease of $PREN{\gamma}$ by dilution of N in ${\gamma}$-phase with an increase in the ${\gamma}$-phase volume fraction and an increase of $PREN{\alpha}$ by enrichment of Cr and Mo in the ${\alpha}$-phase with a decrease in the ${\alpha}$-phase volume fraction.

• Food Science and Preservation
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• v.13 no.5
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• pp.538-542
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• 2006

Physicochemical properties and positional distribution of Hallabong Tangor (Citrus Kiyomi ${\times}$ ponkan) cultivated in heated greenhouse were investigated. About 90% of Hallabong produce fruit within the range of $250{\sim}400g$ fruit weight on a tree, larger fruits were mainly consisted of $400{\sim}450g$ in M16A, a variant species of Hallabong, due to younger tree and fruit thinning. Nevertheless fruit sizes of M16A were larger than Hallabong, and peel thickness of M16A (3.29 mm) was thinner than that of Hallabong (3.51 mm). Hardness of m6h was 994.69g-force, compared to 832.8 g-force of Hallabong on the average. Soluble solids and acid content of Hallabong were $12.20{\sim}12.98^{\circ}Brix$ and $1.08{\sim}1.14%$, while those of M16A were $1.48{\sim}12.63^{\circ}Brix$ and $0.92{\sim}1.00%$, respectively. Vitamin C content of Hallabong was $71.30{\sim}78.77 mg/100 g$, compared to $64.40{\sim}68.01mg/100g$ in M16A. Soluble solid in the part of stem was lower than that of end part among the same segment. Fruit size in the upper part of the tree was larger, the peel was thicket and flesh ratio was lower than the middle or lower part. However, soluble solids and acid content were high, due to cumulative sunshine during cultivation.

• Food Science and Preservation
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• v.20 no.1
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• pp.111-120
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• 2013

Sprassis crispa was cultivated using soybean curd whey, and its antimicrobial activities were examined against those of eight microorganisms that were foodborne pathogens or food-poisoning bacteria. The culture broth of soybean curd whey was superior in mycelium content (17.76 g/L) to that of the defined culture broth, and the ${\beta}$-glucan content was about 10.64 percent (w/w). The antimicrobial activities of the culture broth were confirmed against those of B. cereus, St. aureus, L. monocytogenes and S. typhimurium using the paper disk method. The antimicrobial activity was also maintained after the heat treatment and alcalase treatment. The filtrate with less than 3 kDa M.W. also showed the antimicrobial activity against four strains: B. cereus, St. aureus, L. monocytogenes and S. typhimurium. The minimum inhibitory concentration (MIC) was about 1.26 mg/mL in the B. cereus and 12.6 mg/mL in the St. aureus and L. monocytogenes. The S. typhimurium showed a MIC of 62.8 mg/mL. Thus, the culture of Sparassis crispa using soybean curd whey provides a thermally stable antimicrobial agent that can be used as a natural preservative in the biofood industry.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.43 no.7 s.349
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• pp.162-169
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• 2006

A Micorstrip Bandpass Filter Using DBRs for WLAN ($2.3{\sim}2.4GHz$) applications is designed and an EBG structure is employed in the ground plane of the filter to suppress the stopband responses of the filter. The number of DBRs is chosen as two in consideration of low insertion loss and small size of two filter. The center frequency of the filter to be designed is 2.35GHz and its bandwidth is 140MHz. The responses of two kinds of DBR filters (one with EBG and the other without EBG) are calculated and compared with the measurements. The experimental results are in good agreement with the calculations: The bandwidth and insertion loss of the filter with EBG structure are 3.8% and 1.7dB respectively, while those of the filter without EBG structure are 7% and 1.23dB. It is shown that the insertion loss of the filter is increased and its bandwidth is deceased due to the EBG structure. Also the stopband responses of the filters with EBG structures are shown to be much improved compared with those without EBG.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.44 no.9
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• pp.18-24
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• 2007

We report broadband cascode amplifiers of a single-ended and a balanced amplifier for the millimeter-wave applications. The amplifiers were fabricated using 0.1 ${\mu}m\;{\Gamma}-gate$ PHEMT technology on GaAs substrate. The single-ended cascode amplifier was designed and fabricated by using shunt peaking technology. The fabricated single-ended cascode amplifier shows 3 dB bandwidth of 37 GHz($18.5{\sim}55.5$ GHz) and the maximum $S_{21}$ gain of 9.38 dB. The balanced cascode amplifier using tandem couplers achieves 3 dB bandwidth and the maximum $S_{21}$ gain of 44.5 GHz($21{\sim}65.5$ GHz) and 10.4 dB at 60 GHz, respectively. The 3 dB bandwidth of the balanced cascode amplifier shows 20% lager than the single-ended cascode amplifier.