• The Transactions of the Korean Institute of Electrical Engineers B
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• v.53 no.4
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• pp.221-221
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• 2004

Power system has recently used Double-circuit Line and Multi-circuit Line in the industrial development. This has an advantage of system stability and reliability, but the complexity of the system has a disadvantage that makes it difficult to protect the power line. Double-circuit Line has two operation conditions in the Single-circuit operation and Double-circuit operation, so it has mutual impedance. To make it possible for the remaining single-line to operate independently while there is a fault with first line or when maintenance is needed, a trip region for the single-circuit operation should be set in order to set the relay trip region. An optimal trip region for each operation, a different operational conditions for the relay setting should be calculated. In this paper, trip regions of each operation condition have been compared by considering mutual impedance and fault resistance that led to the calculation of fault impedance. Also, as we know that one of the advantages in the distance relay is the back-up protection, we calculated the trip region(Zone-2) in consideration of the mutual impedance.

• Geomechanics and Engineering
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• v.7 no.1
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• pp.105-131
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• 2014

In this paper, the effects of variability of smear zone characteristics induced by installation of prefabricated vertical drains on the preloading design are investigated employing analytical and numerical approaches. Conventional radial consolidation theory has been adopted to conduct analytical parametric studies considering variations of smear zone permeability and extent. FLAC 2D finite difference software has been employed to conduct the numerical simulations. The finite difference analyses have been verified using three case studies including two embankments and a large-scale laboratory consolidometer with a central geosynthetic vertical drain. A comprehensive numerical parametric study is conducted to investigate the influence of smear zone permeability and extent on the model predictions. Furthermore, the construction of the trial embankment is recommended as a reliable solution to estimate accurate smear zone properties and minimise the post construction settlement. A back-calculation procedure is employed to determine the minimum required waiting time after construction of the trial embankment to predict the smear zone characteristics precisely. Results of this study indicate that the accurate smear zone permeability and extent can be back-calculated when 30% degree of consolidation is obtained after construction of the trial embankment.

• Journal of Electrical Engineering and Technology
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• v.13 no.4
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• pp.1586-1595
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• 2018

For the problem that the complexity of 3-D modeling and multi parameter optimization, as well as the uncertainty of the winding factor of axial flux permanent magnet generator with coreless windings. The complex 3-D model was simplified into 2-D analytic model, and an analytical formula for the winding factor that adapting different coreless stator winding is proposed in this paper. The analytical solution for air-gap magnetic fields, no-load back EMF, electromagnetic torque, and efficiency are calculated by using this method. The multiple objective and multivariable optimization of the maximum fundamental and the minimum harmonic content of back EMF are performed by using response surface methodology. The proposed optimum design method was applied to make a generator. The generator was tested and the calculated results are compared with the proposed method, which show good agreements.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.52 no.9
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• pp.434-441
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• 2003

This paper deals with the temperature characteristics according to the cooling medium and the duct size in model transformers. For the analysis and the temperature-rise tests, two 400kVA model transformers have been manufactured. One has been filled with the alpha oil as the cooling medium and constructed the duct sizes of $3\textrm{mm}$ and $5\textrm{mm}$ in the low-voltage and high-voltage windings respectively. The other has been filled the beta oil and the duct sizes were $4\textrm{mm}$ and $6\textrm{mm}$. The temperature-rise tests have been performed by the back-to-back method and the load factor has been controlled the range of 90%∼130%. The temperature values have been measured by the thermocouple and from the sixteen points in each transformer. A commercial CFD program "FLUENT" has been used for the analysis of temperature distribution. The geometry of transformer has been modeled to 3-dimensional by using the hybrid calculation mesh including the radiator. And also, the natural convection velocity has been measured at the oil top position, and compared with the calculated results.

• Journal of the Korea Fashion and Costume Design Association
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• v.5 no.1
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• pp.13-24
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• 2003

The purpose of this study is to design Jugori model compatible with the body types of the middle-aged women especially from 40 to 59 years old. The result is as follows: We decided five items as the necessary items for designing jugori model : the bust girth (the breast & shoulder width), the B.P length, the neck width, the armhole circumference, and Hwa-jang. The breast & shoulder width are the size that comes out if the bust is divided by the breast & shoulder width on the basis of the side line, and Hwa-jang is a length measured with arms stretched out to 0° direction. With each person's physical characteristics considered, the application of the size of each body types and body parts is as follows: 1. The breast & shoulder width (1/4 portion) : We decided B/4+2cm as a standard size and, we adjusted the extra room on the basis of the discrepancy between the breast width and the shoulder width to make it fit well to the each body type. For the breast width (1/2 portion), we bisected the difference between the breast width and the shoulder width of the bust, and moved Gut-sup to the center of the Sup and Sup-sun for An-sup. According to the body type, the movement of the Sup for the people with big breasts gets bigger because there should be a big difference between the breast width and the shoulder width for them, and for the people with small breasts the movement will be relatively smaller. For the shoulder width (1/2 portion), we curved the back center line after we shortened as much as the difference between the amount of the shoulder width/2+1cm and of B/4+2cm. The movement of back center line will be bigger for a person with leaned-backward body type. 2. The front & back length: We made the front length to B.P length+2.5cm to have Jugori cover the breast point fully around the bust line, which is a vogue nowadays. For an upright body type, we decided the back length as (AH/2.2)+5cm. And for a bent-forward and a leaned-backward body type, we adjusted the calculation formulae differently taking the physical characteristics into account. We decided the back length (A) as (A.H/2.2)+5cm, and the front length (B) as the back length+5cm. So, (A+B) is the sum of the front length and the back length. Going back to the original formula, the front length is B.P+2.5cm. So, we can decide the back length if we subtract B.P+2.5cm from the sum of the front length and the back length. To make well-fit Jugoris, the front & back length are areas that we should pay attention to if we take each person's physical characteristics into consideration. 3. Go-dae (1/2 portion) : We decided Go-dae as the neck width/2+0.5cm. For an upright body type, because the base line which went down vertically from the tragion was straight, we generally decided Go-dae Dalim line as 1.0cm. But we decided Go-dae Dalim line down to 1.5cm for bent-forward type and up to 0.2cm for leaned-backward type because the upper half of the body of them was bent forward or leaned backward from the base line. 4. The armhole : We decided the armhole circumference as A.H/2+2cm with the whole extra room of 4cm. 5. The side line length : We can calculate the side line length to (the back length-the armhole)/2, and, in terms of the trend, 2.5cm will be appropriate.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.19 no.8
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• pp.1765-1772
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• 2015

In the underwater acoustic communication channels, multipath reflection become the cause of obstacle. Generally, equalizer has been applied to overcome these problems. In this paper, the method was proposed to optimize tap-length of decision feedback equalizer using genetic algorithm. After inputting feed-forward filter length and feed-back filter length as genetic information of the genetic algorithm, it optimize tap-length using BER(bit error rate) calculation in accordance with object function. The object function consist of decision feedback equalizer and BER calculation. For the purpose of BER calculation in the object function, the method was proposed to optimize the tap-length of decision feedback equalizer with genetic algorithm using preamble signals. As a result of experiments, the optimized BER is 0.0355 for signals which were received through a 25m receiver and which were applied to calculate BER merely using preamble signals in object function. When all data were used to calculate BER in object function, the optimized BER is 0.0215.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.22 no.10
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• pp.118-125
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• 2008

The outages of transmission lines give big damages to the industrial world Lightning outages occupy above 50[%] among the outages of transmission lines. To decrease the lightning outage rates, it is necessary to try countermeasures considering economical points. For the lightning protection of power transmission lines, it is very important to accurately predict the lightning outage rate because the reliability criterion for transmission line is normally specified as the number of flashovers per 100[km] per year. The phenomenon of an insulator flashover by a lightning stroke is a very complex electromagnetic event. And to calculate the lightning outage rates of transmission lines, so many calculation should be repeated because there are many overhead lines and power lines. Therefore it is necessary to develope a program for it. In this paper, we briefly introduce the basic concept for lightning outage calculation algorithm and the program.

• Korean Journal of Ophthalmology
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• v.32 no.6
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• pp.497-505
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• 2018

Purpose: To evaluate and compare published methods of calculating intraocular lens (IOL) power following myopic laser refractive surgery. Methods: We performed a retrospective review of the medical records of 69 patients (69 eyes) who had undergone myopic laser refractive surgery previously and subsequently underwent cataract surgery at Samsung Medical Center in Seoul, South Korea from January 2010 to June 2016. None of the patients had pre-refractive surgery biometric data available. The Haigis-L, Shammas, Barrett True-K (no history), Wang-Koch-Maloney, Scheimpflug total corneal refractive power (TCRP) 3 and 4 mm (SRK-T and Haigis), Scheimpflug true net power, and Scheimpflug true refractive power (TRP) 3 mm, 4 mm, and 5 mm (SRK-T and Haigis) methods were employed. IOL power required for target refraction was back-calculated using stable post-cataract surgery manifest refraction, and implanted IOL power and formula accuracy were subsequently compared among calculation methods. Results: Haigis-L, Shammas, Barrett True-K (no history), Wang-Koch-Maloney, Scheimpflug TCRP 4 mm (Haigis), Scheimpflug true net power 4 mm (Haigis), and Scheimpflug TRP 4 mm (Haigis) formulae showed high predictability, with mean arithmetic prediction errors and standard deviations of $-0.25{\pm}0.59$, $-0.05{\pm}1.19$, $0.00{\pm}0.88$, $-0.26{\pm}1.17$, $0.00{\pm}1.09$, $-0.71{\pm}1.20$, and $0.03{\pm}1.25$ diopters, respectively. Conclusions: Visual outcomes within 1.0 diopter of target refraction were achieved in 85% of eyes using the calculation methods listed above. Haigis-L, Barrett True-K (no history), and Scheimpflug TCRP 4 mm (Haigis) and TRP 4 mm (Haigis) methods showed comparably low prediction errors, despite the absence of historical patient information.

• Journal of the Korean Society of Costume
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• v.58 no.2
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• pp.162-180
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• 2008

The purpose of this study is to find the basic design factors that affect the changes in body surface lines caused by lower limb movements, thereby resulting in slacks that fit well regardless of whether the human form is static or in motion. Using unmarried female university students aged 18-24 as subjects, a total of 32 body surface lines (15 body surface total lines and 17 body surface segment lines) were measured in one static and 9 movement poses, The analysis first involved the calculation of the expansion and contraction rates per body part in body surface line in 9 lower limb movements, Second, a factor analysis was conducted using the expansion and contraction rates of these changes in body surface line. The results of this study are as follows, According to the factor analysis, basic design factors that affect changes in body surface lines comprised 8 types of factors as illustrated in fig, 2-fig, 9, which explained 79.2% of total variate for the variables studied, Factor 1, comprising the lower segment of center back leg line, center front leg line and inner leg line, and lower limb girth except midway thigh girth and ankle girth below hip girth, accounted for 30.3% of total variance, Factor 2, comprising waist girth, the total and upper segment of center back leg line and center tront leg line, and front and back segment of crotch length, explained 17.4% of total variance, Factor 3, the total and upper segment of lateral leg line at the center, accounted for 56.5% of total variance in accordance with Factors 1, 2, and 3, Factor 4 was the contracting upper part of lower leg between legscye girth and midway thigh girth, Factor 5 comprised the total and upper segment of inner leg line and posterior knee girth, Factor 6 was the total crotch length, Factor 7 was the ankle girth, Factor 8 was the abdomen girth.

• Journal of the Korean Home Economics Association
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• v.34 no.4
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• pp.249-263
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• 1996

According to the design method for constructing the G gori(the traditional Korean jacket)collar, there are differences in form after its completion. In the construction design of the midsection of the gusset as in that of the basic G gori, not only was the positioning of the two sides of the collar not smooth, but also, when the collar strip was attached, there would be an imbalance on one side or the other so that it was difficult to achieve symetry. Therefore in this project, by applying the pattern design of the gusset midsection to that of the collar midsection, not only did attaching the collar and the collar strip create a visual effect by equalizing the lengths of the tow sides, but the construction was also easy. This method of construction introduces the three-dimensional aspect of the human form in its conic, spherical and cylindrical aspects, so that, through schematizing the scientific character of Korea's clothing, its appropriateness is verified. As a matter of fact, since th-ere in no standardization of pattern whether for educational use or for mass-produced clothing, so that even the patterns used in computer-assisted design are executed according to the designer's personal skill, the reality is that after completion of construction the quality has not been uniform. For this schematization, inverse calculation of measurements pertaining to the calculation formula and of teaching materials has been referenced. In particular, the partial requlation of the calculation formula pertaining to the basic pattern construction, the method of making the collar midsection, and the construction method of the extreme and mean ratio adjustment can be adjusted for all measurements, thereby providing the establishment of a design criterion and the possibility of the standardization of construction methods. The production method for the pattern design is as follows: 1) The conic angle for the G gori's girth, length and neck width is fixed at 70 degrees. 2) The radius of the cone is B/2. 3) The calculation formula is B/4 + 1.5cm 4) The armhole formula is B/4, the same as in the basic method. 5) The width formula is B/10. 6) The ratio of the collar junction(width of collar + width of collar strip)to the gusset length is 5:8. 7) The length of the side seam is a length intersecting the armhole line and the conic radius (B/2), that is an arc that exceeds the length of the G gori's midsection; the component ratio of this length to the collar junction is accordingly 13:5. 8) The curve frame length of the back midsection is an arc exceeding B/4(the armhole line). 9) The ratio of the sleeve opening calculation formula to the armhole length is 8:5, forming an arc with the midsection length.