• Journal of Korean Tunnelling and Underground Space Association
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• v.12 no.3
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• pp.239-245
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• 2010

The present study is about an efficient extraction of tunnel cross sections from huge point cloud achieved by a terrestrial laser scanner. A method, using a hash-based data structure, is introduced, by which point clouds, potentially composing cross sections, are extracted along a tunnel center line. The center line is estimated by linking points which are drawn in the middle of pseudo cross sections based on the hash-based data structure. Point clouds of a same thickness are extracted at a same interval along the center line. In result, it took less than 3 seconds and 124 MB of memory to extract, out of the 7.5 million points, the point clouds of 1 m interval and 0.1 m thickness. A manual operation, however, was needed to fix the outliers on the center line and to select both start and end points on it.

• The Research Journal of the Costume Culture
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• v.31 no.5
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• pp.640-650
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• 2023

This study aimed to suggest a suitable collar pattern by visually evaluating the appearance of the amount of collar drape by the starting position of the lapel line of a double-breasted tailored jacket using a 3d virtual fitting program. It created an avatar based on the mean size of women in their 20s (the 8th Size Korea) using clo network (double fastening: 10cm, collar width: 4.5cm, collar stand: 3cm, and lapel width: 8.5cm). The starting of the lapel twist line was waistline level, the 1/2 level of bustline and waistline, or bustline level, and collar laying amount was 4.5, 5.5, 6.5, or 7.5cm. It was evaluated by garment construction experts using 5, 6, and 4 items on the front, sides, and back, respectively. Descriptive statistics, F-test, Duncan-test, and reliability analysis were conducted using SPSS 22. When collar laying amount was 6.5cm, it was best rated regardless of the starting point. Under waist line, when collar laying amount was 6.5cm, it was best rated regardless of the starting point. When collar laying amount was large, the collar's outline length increased, resulting in unnecessary wrinkles from the neckline to the lapel, affecting the overall collar appearance. When collar laying amount was the smallest, the collar was lifted and the width was narrowed, exposing the seam connecting the collar and neckline. The length of the collar's outline varied depending on collar laying amount, which was important to make the outline sit comfortably on the body.

• Korean Journal of Applied Biomechanics
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• v.26 no.3
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• pp.315-321
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• 2016

Objective: The aim of this study was to analyze effects of the toe-spring angle of bobsleigh shoes on start speed lap time to develop Korean-specific bobsled shoes suitable for winter environments and for domestic players on the basis of sports science and optimized biomechanical performance. Method: Seven Korean bobsleigh athletes participated in this study, with three pairs of sprint spikes from three companies (Type A, Type B, Type C). To analyze sprint lap time and forefoot bending angle for each shoe, participants were instructed to drag a sled 15 meters from the start line at a maximum sprint. forefoot bending angle was collected by a high speed camera, and lap time speed was measured. Results: Lap time for type B shoes was $3.52{\pm}0.17sec$, type A was $3.55{\pm}0.19sec$, and type C was $3.56{\pm}0.18sec$. Forefoot bending angles were: angle 1, $6.88{\pm}5.55^{\circ}$; angle 2, $9.23{\pm}6.38^{\circ}$; angle 3, $15.56{\pm}5.39^{\circ}$; angle 4, $9.54{\pm}3.85^{\circ}$; angle 5, $9.22{\pm}5.08^{\circ}$; angle 6, $7.66{\pm}6.44^{\circ}$; and angle 7, $4.30{\pm}6.24^{\circ}$ (p<.001). Forefoot bending in angle 3 was as follows: type A, $16.47{\pm}6.01^{\circ}$; type B, $14.30{\pm}4.96^{\circ}$; and type C, $15.90{\pm}5.17^{\circ}$. Conclusion: Hard outsoles and midsoles are better than soft type for reduced start lap time when developing a prototype Korean bobsled shoe.

• Land and Housing Review
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• v.8 no.3
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• pp.189-200
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• 2017

The work breakdown structure and the precedence relations by work activity are very important because they are the basic data for estimating the construction duration in the construction work. However, there is no standard to accurately estimate the construction duration since the size of the school facilities construction is smaller than the general construction work. Therefore, some schools are unable to open in March or September and the delay of the construction duration can cause damage to the students. To solve this problem, this study developed a work breakdown structure of school facilities construction work and analyzed the precedence relations by work activities. The work breakdown structure of the school facilities construction is composed of three steps. The operations corresponding to level 1 and level 2 are as follows. (1) 2 preparatory work categories; preparation period and temporary construction. (2) 17 architectural work categories; temporary construction, foundation & pile work, reinforced concrete work, steel roof work, brick work, plaster work, tile work, stone work, waterproof construction, wood work, interior construction, floor work, metal work, roof work, windows construction, glazing work and paint construction. (3) 7 mechanic and fire work categories; outside trunk line work, plumbing work, air-conditioning equipment work, machine room work, city gas plumbing work, sanitation facilities and inspection & test working. (4) 4 civil work categories; wastewater work, drainage work, pavement work and other work. (5) 1 landscaping work categories; planting work. The work breakdown structure was derived from interviews with experts based on the milestones and detailed statements of existing school facilities. The analysis of precedence relations by school facilities work activity utilized PDM(Precedence Diagramming Method)which does not need a dummy and the relations were applied using FS(Finish to Start), FF(Finish to Finish), SS(Start to Start), SF(Start to Finish). The analysis of this study shows that if one work activity is delayed, the entire construction duration may be delayed because the majority of the works are FS relations. Therefore, it is necessary to use the Lag at the appropriate time to estimate the standard construction duration of the school facility construction. Lag is a term used only in the PDM method and it is used to define the relationship between the predecessor and the successor in creating the network milestone. And it means the delay time applied to the two work activities. The results of this study can reasonably estimate the standard construction duration of school facilities and it will contribute to the quality of the school facilities construction.

• Journal of Industrial Convergence
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• v.19 no.5
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• pp.21-34
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• 2021

The purpose of this study is to find out what the investment efficiency of BW is from an investor's point of view and to suggest an efficient investment plan to investors. The research method is to investigate the coupon interest rate, maturity interest rate, issuance date, right exercise start and end date, maturity date, exercise price, etc. for BW issued from 2014 to July 2021. By connecting them, it was attempted to quantitatively understand the efficiency of investment in BW and the effect of new stock acquisitions. As a result of the study, the ratio of the number of days in excess of the exercise price was 41.3% of the available days for new stocks, so it was analyzed that the investment efficiency of bonds with warrants was not high. The return on the exercise start date was 24.8% on average and the return on the end date was 52.6% on average, showing a positive return on average, so it was derived in line with investor expectations. The number of stocks with negative returns on the exercise start date was 1.47 times higher than the number of stocks with positive returns, and the number of stocks with negative returns on the end date was 1.16 times higher than the number of positive stocks.

• The Transactions of the Korean Institute of Power Electronics
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• v.17 no.3
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• pp.246-251
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• 2012

This paper proposes a new position compensation method for misaligned Hall-effect sensors of BLDCM(Brushless DC Motor). If the Hall-effect sensors are installed at wrong position, the exact rotor position cannot be obtained. Therefore, when the BLDCM is controlled with this wrong position, the torque ripple can be increased and the average torque also decreases. The back-EMF of BLDCM can be obtained by using the voltage equation and by multiplying the back-EMF constant and rotor speed. At a constant speed, the estimated back-EMF by using the multiplication of the back-EMF constant and rotor speed is constant, but the estimated back-EMF from the voltage equation decreases at the commutation point because the line-to-line back-EMF of two conducting phases is start to decrease at this point. Therefore, by using the difference between these two estimated back-EMFs, the commutation point of the phase current can be determined and position compensation can be carried out. The proposed position correction method doesn't require additional hardware circuit and can be easily implemented. The validity of the proposed position compensation method is verified through several experiments.

• The Journal of Korean Academic Society of Nursing Education
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• v.14 no.1
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• pp.30-37
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• 2008

Purpose: This study proposed to examine the effects of a blended-learning orientation program executed for nursing students' clinical practice. Method: The participants were 61 nursing students in the experimental group and 57 in the control group. For the experimental group, a blended-learning orientation program was executed by e-learning (on-line) and lecture-led training (off-line) from two-week before the start of clinical practice in medical-surgical nursing. For the control group, orientation was given in the traditional lecture-led training by distributing printed materials before clinical practice. A pre-test was conducted on the experimental and control group before clinical practice, and a post-test was conducted after two-week of clinical practice in order to examine the effects of the orientation program. Results: After two-week of clinical practice, differences were observed between the experimental group and the control group in adaptation to clinical practice (F=10.242, p=.002), communication skills (F=4.305, p=.040) and clinical competence (F=6.823, p=.010). Conclusions: The blended-learning orientation program enhanced nursing students' adaptation to clinical practice, improved their communication skill and increased their clinical competence. Accordingly, it is recommended to develop and apply practical education using blended-learning in the area of nursing science.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2001.04a
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• pp.399-404
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• 2001

In CNC machining, a 3D(3-dimension) linear segment and a 2D(2-dimension) circular arc are general forms given by CAD/CAM system. Generally, the 2D circular arc machining is processed using dividing into some linear segments. A 3D circular arc also don't exist in the standard form of NC data. This paper present a algorithm and method for real-time machining of a circular arc(not only the 2D one, but also the 3D one). The 3D circular arc machining is based on the 2D circular arc machining. It only needs making a new coordinate system, converting given 3D points(a start point, a end point, and a center point of a 3D circular arc) into points of the new coordinate system, and processing a inverse transformation about a interpolated point. The proposed algorithm was implemented and simulated on PC system. It was confirmed to give a gcod result.

• Proceedings of the KIEE Conference
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• 2006.04a
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• pp.228-230
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• 2006

While trains perform a complete precision stopping control at stop point, it is essential to keep better commuters comfort in prompt. Because a train's brake force tends to increase a brake effort in a low speed and a low brake effort, a brake force in motor cars must be increased to keep better passenger comfort, to control the special braking qua1ities and to prevent the impact of the automatic coupler rather than trailer's, Rail cars must have a special braking process for the train stopping control. In the train stop mode, the train stopping control is designed to start at 20km/h. It starts by Dynamic brake blending, and then finally stops by only the friction. If these process are not exactly activated, the train may fail a complete precision stop. In this report, it studied the electric and friction brake processing during the precious stopping control. To achieve exact test results, the speed reference has to be reduced the calculated difference. In the precision stopping control. the ways of the keeping brake force in motor car was analyzed and some solutions of controling air pressure was brought up by means of direct test in main line, This study was based on line 5 in Seoul Metropolitan subway.

• Communications of Mathematical Education
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• v.22 no.4
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• pp.417-444
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• 2008

Many research papers on the college students' functional concept show they have poor understanding on this topic. To compare the results with that of Korean students, four interrelated topics are chosen: How do they understand the concept of function?; what are their misconceptions including epistemological obstacles?; How do the function concepts develop and are acquired? For this a survey has been conducted to 95 engineering students just before they start Calculus course. We have done research on other major areas including psychology, economics and statistics to see how function is defined in these areas. Function definitions from US math text books are also introduced. Based on the these and the survey, some suggestions are made on the new curriculum which treat function as a correspondence relation. Vertical line test should be added to the Algebra II/Pre calculus course to check the univalent property.