• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.8 no.1
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• pp.37-44
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• 2015

In this paper, we have investigated a selective assembly method of single-walled carbon nanotubes (SWCNTs) on a silicon substrate using only photolithographic process and then proposed a fabrication method of field effect transistors (FETs) using SWCNT-based patterns. The aminopropylethoxysilane (APTES) patterns, which are formed for positively charged surface molecular patterns, are utilized to assemble and align millions of SWCNTs and we can more effectively assemble on a silicon (Si) surface using this method than assembly processes using only the 1-octadecyltrichlorosilane (OTS). We investigated a selective assembly method of SWCNTs on a Si surface using surface-programmed APTES and OTS patterns and then a fabrication method of FETs. photoresist(PR) patterns were made using photolithographic process on the silicon dioxide (SiO2) grown Si substrate and the substrate was placed in the OTS solution (1:500 v/v in anhydrous hexane) to cover the bare SiO2 regions. After removing the PR, the substrate was placed in APTES solution to backfill the remaining SiO2 area. This surface-programmed substrate was placed into a SWCNT solution dispersed in dichlorobenzene. SWCNTs were attracted toward the positively charged molecular regions, and aligned along the APTES patterns. On the contrary, SWCNT were not assembled on the OTS patterns. In this process, positively charged surface molecular patterns are utilized to direct the assembly of negatively charged SWCNT on SiO2. As a result, the selectively assembled SWCNT channels can be obtained between two electrodes(source and drain electrodes). Finally, we can successfully fabricate SWCNT-based multi-channel FETs by using our self-assembled monolayer method.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.38 no.3
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• pp.95-99
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• 2015

The IRR(internal rate of return) is often used by investors for the evaluation of engineering projects. Unfortunately, it has serial flaws: (1) multiple real-valued IRRs may arise; (2) complex-valued IRRs may arise; (3) the IRR is, in special cases, incompatible with the net present value (NPV) in accept/reject decisions. The efforts of management scientists and economists in providing a reliable project rate of return have generated over the decades an immense amount of contributions aiming to solve these shortcomings. Especially, multiple internal rate of returns (IRRs) have a fatal flaw when we decide to accep it or not. To solve it, some researchers came up with external rate of returns (ERRs) such as ARR (Average Rate of Return) or MIRR (MIRR, Modified Internal Rate of Return). ARR or MIRR. will also always yield the same decision for a engineering project consistent with the NPV criterion. The ERRs are to modify the procedure for computing the rate of return by making explicit and consistent assumptions about the interest rate at which intermediate receipts from projects may be invested. This reinvestment could be either in other projects or in the outside market. However, when we use traditional ERRs, a volume of capital investment is still unclear. Alternatively, the productive rate of return (PRR) can settle these problems. Generally, a rate of return is a profit on an investment over a period of time, expressed as a proportion of the original investment. The time period is typically the life of a project. The PRR is based on the full life of the engineering project. but has been annualised to project one year. And the PRR uses the effective investment instead of the original investment. This method requires that the cash flow of an engineering project must be separated into 'investment' and 'loss' to calculate the PRR value. In this paper, we proposed a tabulated form for easy calculation of the PRR by modifing the profit and loss statement, and the cash flow statement.

• Clinical and Experimental Reproductive Medicine
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• v.25 no.1
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• pp.93-102
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• 1998

Normal and abnormal follicular growth and steroidogenesis depend on gonadotropins as well as intraovarian peptides, which may mediate or potentiate gonadotropin action. Inhibin also affect follicular development and steroidogenesis and may play a role in dominant follicle selection and follicular atresia. Therefore, we studied the differences of serum inhibin, gonadotropin and androgen levels in the women with only the ultrasound findings and no disorder, and polycystic ovary (PCO) with ovulatory disturbance. We prospectively analysed forty-three women with PCO. The diagnosis of PCO was based on typical appearance of the ovaries on TVS. Twelve women with regular menstrual cycle and normal ovarian morphology were selected as control. Basal levels of inhibin, luteinizing hormone (LH), follicle stimulating hormone (FSH), estradiol $(E_2)$, testosterone (T), androstenedione (ADD), dehydroepiandrosterone-sulfate (DS), prolactin and TSH in serum were determined. There were significant differences in basal LH levels and LH/FSH ratio between the control and the women with PCO. The basal levels of inhibin and $E_2$ in the oligo-amenorrheic PCO (N=34) were significantly higher than those in the control. There was higher negative correlation between the inhibin and T levels in the oligo-amenorrheic PCO, but, not in the regular cycling PCO. Also, there was higher positive correlation between the LH and T levels in the oligo-amenorrheic PCO, but not in the regular cycling PCO. These data presume that the initial event of PCO is elevated pituitary LH secretion. Elevated levels of LH may down-regulate LH receptors on granulosa cells and also cause hypertrophy of the thecal layer. High level of androgen secreted by the hypertrophied thecal layer may stimulate inhibin secretion from granulosa cells and can be converted to estrogen by extraovarian tissues and could serve to augment pituitary sensitivity to GnRH with a resultant secretion of more LH than FSH. Inhibin may inhibit FSH action on granulosa cell in the PCO follicle, impairing follicular development and dominant follicle selection resulted in ovulatory disturbance.

• Clinical and Experimental Reproductive Medicine
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• v.26 no.3
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• pp.355-362
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• 1999

Objective: This study was performed to compare the clinical response to controlled ovarian hyperstimulation (COH) of in vitro fertilization and embryo transfer (IVF-ET) according to the size of baseline ovarian cyst. Method: From February 1992 to March 1999, a retrospective analysis was done of 272 cases who underwent COH using mid-luteal phase long protocol of gonadotropin-releasing hormone agonist (GnRH-a) for IVF-ET. These cases were divided into four group; group 1 (n=63) had cysts with mean diameters between 20.0 and 29.0 mm on their baseline ultrasound on cycle day 3, group 2 (n=57, $30.0{\sim}49.0mm$), group 3 (n=68, >50.0 mm) and control group (n=84). Cases were excluded according to the following criteria; pure male factor infertility, the presence of only one ovary, high CA-125 level and previous endometriosis. Results: There were no statistically significant differences between cases with baseline ovarian cyst <50.0 mm in diameter and control group in any of the parameters. However, cases with baseline ovarian cyst>50.0 mm in mean diameter needed more amount of human menopausal gonadotropin (hMG), showed significantly lower estradiol ($E_2$) level, the number of follicle >15.0 mm on the day of human chorionic gonadotropin (hCG) administration, the number of oocytes retrieved, the number of mature oocytes, and pregnancy rate compared with control group. Conclusion: This study suggests that cases with baseline ovarian cyst <50.0 mm in diameter do not adversely impact on IVF-ET outcome. However, cases with baseline ovarian cyst >50.0 mm in diameter had adverse effects on various parameters. Therefore, to improve the outcome of IVF-ET in these cases, ovarian cyst aspiration prior to initiating COH may be required.

• Clinical and Experimental Reproductive Medicine
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• v.26 no.1
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• pp.75-81
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• 1999

The beneficial effect of glucose and phosphate ions in culture medium on the development of human embryos in vitro has not been fully elucidated. The purpose of this study was to evaluate the influence of fertilization and culture of embryos in glucose/phosphate-free m-TALP medium on pregnancy rates in IVF-ET program. The patients in 244 IVF-ET cycles received GnRH agonist + HMG regimens. A does of 10,000 IU HCG was administered when two or more dominent follicles reached 18mm in diameter. Thirty-six hours after HCG, oocytes were recovered transvaginally using ultrasound guidance. Aspirated oocytes were matured for 4 to 6 h in TCM-199 supplemented with 10% follicular fluid (FF). Insemination was carried out with 50,000 motile spermatozoa in TCM-199 + 10% FF or m-TALP + 5% FF + 5% fetal cord serum (FCS) according to experimental design. After 6 h, oocytes were washed 3 to 4 times and cultured in each fresh medium. After 20 h, oocytes were freed from cumulus/corona cells and examined for the presence of pronuclei. Fertilized oocytes were transferred into each co-culture drops and cultured for further incubation. On day 3, embryo transfer was performed with grade 1 and 2 embryos. Monolayers for co-culture of embryos were prepared by plating $1{\times}10^5$ cumulus cells/ml in 10ul drop of TCM-199 + 10% FF or m-TALP + 5% FF + 5% FCS media 24 h prior to the onset of co-culture. Development to 4 to 16 cell stage was observed at 70x magnification following two days of incubation. Pregnancy was confirmed by detecting increasing serum ${\beta}$-hCG concentrations for 11 days following embryo transfer. Data were analyzed by ${\chi}^2$-test. Oocytes from 244 IVF-ET cycles were randomized. The number of cycles and mean age of patients were 97 and 147, 31.3 yrs and 31.2 yrs for TCM-199 (control) and m-TALP groups, respectively. The mean number of retrieved oocytes/cycle, fertilization rates, number of embryos transferred/ET and pregnancy rates were 11.1 and 10.3, 65.1% and 67.3%, 4.1 and 4.7, 28.9% and 43.8% for TCM-199 and m-TALP groups, respectively. Differences in the pregnancy rates were found between control and m-TALP groups (p<0.05). The pregnancy rate of patients divided according to maternal age groups of ${\leq}30$, 31-35, $36{\leq}$ were 44.4% and 49.0%, 26.1% and 41.3%, 29.2% and 41.2% for control and m-TALP groups, respectively. These data indicate that culture of human embryos in glucose/phosphate-free m-TALP medium improves pregnancy rates.

• Clinical and Experimental Reproductive Medicine
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• v.35 no.2
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• pp.111-118
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• 2008

Objective: The purpose of the present study was to examine the hormonal regulation of RGS-2 in the rat ovary. Methods: Immature rats were injected with 10 IU of PMSG to induce multiple growth of preovulatory follicles and 10 IU of hCG to induce ovulation. Northern blot analysis performed for gene expression and in situ hybridization performed for mRNA localization. Results: Northern blot analysis revealed that pregnant mare's serum gonadotropin (PMSG) treatment did not affect RGS-2 mRNA levels. In contrast, human chorionic gonadotropin (hCG) treatment of PMSG-primed rats resulted in an increase in RGS-2 expression within $1{\sim}3\;h$. The major cell-types expressing RGS-2 mRNA were oocytes regardless of follicle size. Interestingly, hCG treatment caused the stimulation of RGS-2 gene expression in granulosa cells of preovulatory and growing follicles. In contrast, cell types expressing RGS-2 protein were theca cells regardless of hCG treatment. Like in vivo, treatment of preovulatory granulosa cells with LH in vitro stimulated RGS-2 levels within 1 h. Interestingly, GnRH antagonist II enhanced the stimulatory action of LH. Conclusion: The present study demonstrates the LH/hCG induction of RGS-2 in preovulatory granulosa cells and suggests a role of RGS-2 in Gq protein signaling pathway during ovulation.

• The korean journal of orthodontics
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• v.34 no.5 s.106
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• pp.380-393
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• 2004

The Purpose of this study was to investigate the dentoalveolar compensation according to anteroposterior skeletal discrepancy in normal occlusion and to evaluate cephalometric parameters that quantitatively describe dental compensations. The study consisted of 90 subjects (50 males. 40 females) who were selected among specimens of normal occlusion at Seoul National, University Dental Hospital, Dept. of Orthodontics. Lateral cephalograms in centric occlusion were traced and digitized for each subject. According to the anteroposterior skeletal pattern the sample was divided into three groups. Cephalometric data were analyzed for the three groups using the SPSS program. Independent t-test, correlation analysis and regression analysis were carried out. The results were as fellows: Dentoalveolar compensation was found in upper and lower incisor inclination and occlusal plane inclination. As the mandible located anterior to the maxilla, the maxillary incisors incisors more labially. the mandibular incisors more lingually, and the occlusal plane continued to flatten. The dental parameters most correlated with anteroposterior skeletal discrepancy were L1 to SN and L1 to FH. Among the compensatory dentoalveolar changes, lower incisor inclination was strongly related to the anteroposterior jaw relationship and played au imposrtant role in obtaining a normal incisor relationship U1 to PtGn and L1 to APog were constant irrelevant to anteroposterior skeletal discrepancy.

• Clinical and Experimental Reproductive Medicine
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• v.22 no.2
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• pp.203-210
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• 1995

Many oocytes fail to fertilize and cleave in vitro and many embryos transferred back to uterus fail to implant or maintain implantation. Chromosomal abnormalities in the male and female gametes may contribute to this loss. The higher incidence of meiotic chromosomal abnormalities bas been found in oocytes than in sperm. The wide range of incidence of chromosomal abnormalities in unfertilized oocytes has been reported in human IVF program (26-63%). However, factors affecting chromosomal abnormalities are not well understood. The present study has been conducted to investigate effects of the method for ovarian hyperstimulation, women's age, and the number of oocytes retrieved per patients on the incidence of numerical chromosomal abnormalities. Five hundred eighty four unfertilized metaphase II oocytes were subjected to chromosomal analysis. Included unfertilized oocytes were from 220 patients (mean $age=32.7{\pm}3.0$) and three hundred thirty oocytes were legible for analysis. Two hundred fourty five oocytes out of 330 (73.3%) were normal, while 38 (11.5%) were hyperploidy, 35 (10.6%) were hypoploidy, and 12 (3.6%) were diploidy. Significant difference in chromosomal abnormalities was not found between two patient groups stimulated by follicular stimulating hormone/human menopausal gonadotrophin (FSH/HMG) (25.9%) and gonadotrophin-releasing hormone agonist/follicular stimulating hormone/human menopausal gonadotrophin (GnRHa/FSH/HMG) (28%). There was a tendency of increasing chromosomal abnormalities in unfertilized oocytes from older patients (<30 yrs: 20.3%, 30-34yrs: 26.9%, >34 yrs: 35.3%). The number of oocytes retrieved per patient had no effect the incidence of chromosomal abnormalities (1-5: 31. 4%, 6-10: 29.8%, 11-15: 28.6%, > 15: 16.5%). These results from the present study suggest that the chromosomal abnormalities observed in the unfertilized oocytes has not affected by the stimulation methods, patient's age, and the number of oocytes retrieved per patients.

• Clinical and Experimental Reproductive Medicine
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• v.37 no.3
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• pp.253-259
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• 2010

Objective: To evaluate if there is any correlation between the growth rate of dominant follicles and clinical characteristics or outcome variables in women undergoing controlled ovarian hyperstimulation (COH). Methods: This study was performed in 313 in vitro fertilization (IVF) cycles. Follicle stimulating hormone (FSH), luteinizing hormone (LH) and estradiol (E2) were measured on day 3 of menstrual cycle, and serial ultrasonographic measurement of the diameter of growing follicles was performed. The growth rates of dominant follicles calculated by diameter difference divided by days were correlated with clinical characteristics and outcome variables. Results: There was no significant difference in the growth rate of the dominant follicles between gonadotropin releasing hormone (GnRH) agonist and antagonist cycles. No significant correlation was found between the growth rates and evaluated factors such as age, body mass index, LH, FSH, $E_2$, retrieved oocytes and fertilization rate. Conclusion: The Growth rate of dominant follicles seems to show an independent feature of basal characteristics and ovarian response.

• Clinical and Experimental Reproductive Medicine
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• v.38 no.1
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• pp.37-41
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• 2011

Objective: To compare the effectiveness and convenience of a pen device for the self-administration of follitropin ${\beta}$ with a conventional syringe delivering follitropin ${\beta}$ solution in patients undergoing IVF-ET. Methods: GnRH agonist long protocol was used for controlled ovarian stimulation (COS) in all subjects. A total of 100 patients were randomized into the pen device group or the conventional syringe group on the first day of COS. Local tolerance reactions were assessed within 5 minutes, at 1 hour and at 3 hours after each injection. On the day of hCG injection, patients were asked to rate their overall pain and convenience experienced with self-injection on a visual anlaogue scale (VAS). Results: There were no differences in patients' characteristics between the two groups. The duration of COS was significantly shorter in the pen device group than in the conventional syringe group. Patients included in the pen device group needed a significantly smaller amount of follitropin ${\beta}$. However, no differences between the two groups were found in IVF results and pregnancy outcome. The incidence of local pain within 5 minutes, at 1 hour and at 3 hours after the injection was significantly lower in the pen device group. VAS scores indicated that injections using the pen device were significantly less painful and more convenient. Conclusion: The pen device for self-administration of follitropin ${\beta}$ is less painful, safer and more convenient for the patients, and can be more effective because of the shorter duration and smaller dose of follitropin ${\beta}$ when compared with the conventional syringe.