• Journal of the Korea Safety Management & Science
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• v.15 no.4
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• pp.435-448
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• 2013

The aim of this study is to investigate and develop the extended models for Economic Cash Amount(ECA), Cash Break Even-Point(BEP), and Cash Flow Statement(CFS) by referencing systematic literature review in the field. The study develops three extended models to determine the optimal cash amount: ECA model with interest opportunity cost, financing transaction cost and financing fail cost, ECA model with daily cash supply and interest opportunity cost, ECA model with financing fail cost and interest opportunity cost. Earnings Before Interests, Tax, Depreciation and Amortization(EBITDA) is obtained by subtracting noncash depreciation costs from Earning Before Interest and Tax(EBIT), which is efficient metric to evaluate operating cash flow. The research also develops two extended Cash BEP models, considered as interest and corporate tax, in order to indentify the break-even point as EBITDA equals zero. Furthermore, this paper proposes the modified version of CFS by introducing the reclassification of operating and financing accounts in the statement of financial position. In addition, the study also present the reclassification of five types of profit, such as gross profit, EBIT, ordinary profit, special profit, and net profit within the statement of comprehensive income. In order to provide a better understanding of the proposed cash flow models, numerical examples, such as two-sample t test and Analysis of Variance(ANOVA), are presented to demonstrate the statistical significance according to the industrial types for net working capital(i.e cash-to-cash), net profit, operating cash flow and free cash flow.

• Journal of Korean Academy of Fundamentals of Nursing
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• v.6 no.2
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• pp.267-276
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• 1999

The purpose of this study was to identify risk factors predictive of alterations in skin integrity during the intraoperative period. The predictive risk factors were studied for intraoperative pressure sores from December 1998 through January 1999. A sample of 220 patients was selected from the operating room schedule of a University Hospital in Pusan. There were two criteria in including patients : the operation lasted longer than 2 hours and the absence of skin break-down according to NPUAP criteria. The data were analized by SPSS/PC, Stepwise multiple logistic regression was used to identify the variables which were predictive of alterations in skin integrity. Of the 220 patients studied, 41 patients (18.6%) developed stage 1 pressure sores in the immediate postoperative period. In relation to skin changes, three independent variables emerged from the stepwise multiple logistic regression as being significant (p<0.05). Factors predictive of pressure sore formation included low serum albumin(p=0.000), prone position while undergoing surgery(p=0.0004), time on the operating table(p=0.0165). Among the intrinsic factors, serum albumin was the most significant causal factor in pressure sores development in the intra-operative period. Pressure and shearing force were the most significant extrinsic factors in pressure sores development. From the results of this study we concluded that the primary nursing goal is the maintenance of the proper patient' position during the intraoperative period. Also imperative for sore prevention is the reduction of surgery time and improving preoperative nutritional status.

• Tribology and Lubricants
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• v.33 no.3
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• pp.119-125
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• 2017

In this study, we perform a numerical analysis to predict the film thickness and lubrication regions for a thrust ball bearing under different operating conditions. Film thinning and replenishment affect the film thickness in starved lubrication. As the inlet meniscus position is brought to the edge of the Hertz contact, the thin film thickness is calculated as starved equation. We use a film replenishment model to determine the recovery film thickness between rolling elements. We use a hydrodynamic model to describe film recovery, that results from the effects of surface tension. In this model, we consider the surface tension gradient in fluid depression as the driving force for fluid recovery. We use Fourier transform method to determine the time-dependent depth of depressed oil. We calculate the change in the central film thickness graphically by using the recovery equation in starved elastohydrodynamic lubrication(EHL) under operating conditions that include numbers of balls, sliding velocity, applied force, and ambient film thickness. We evaluate the degree of starvation by using the distance from the center of the contact area to the meniscus position. Parched lubrication, a phenomenon where the film thickness decreases consistently, occurs at the severe condition. We determine optimal values with respect to the numbers of balls, and sliding velocity. The investigation can contribute to the design operating conditions for proper lubrication.

• Tunnel and Underground Space
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• v.32 no.3
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• pp.231-242
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• 2022

In this study, we developed a robot operating system (ROS)-based autonomous driving robot that estimates the robot's position in underground mines and drives and returns through multiple waypoints. Autonomous driving robots utilize SLAM (Simultaneous Localization And Mapping) technology to generate global maps of driving routes in advance. Thereafter, the shape of the wall measured through the LiDAR sensor and the global map are matched, and the data are fused through the AMCL (Adaptive Monte Carlo Localization) technique to correct the robot's position. In addition, it recognizes and avoids obstacles ahead through the LiDAR sensor. Using the developed autonomous driving robot, experiments were conducted on indoor experimental sites that simulated the underground mine site. As a result, it was confirmed that the autonomous driving robot sequentially drives through the multiple waypoints, avoids obstacles, and returns stably.

• The Journal of the Convergence on Culture Technology
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• v.6 no.4
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• pp.545-551
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• 2020

The Ddaekbo and Chinese envoy story has been known as a folktale criticising the helpless ruling class by the people. It's been explained that the hand gesture communication with the signifier theory. And it's been analysed that the Chinese envoy is in the 'The Other' position with Lacan theory. But it showed that the winning factor of Ddaekbo could be elucidated by the difference of the desire feature of two conflicting subjects in the study. It claims that the Ddaekbo's wanting is the impulse not the desire and he's won the test by the repetitive and persistence impulse. And it's proper that the position of the Chinese envoy is 'the return of The Real' not the 'The Other'. It's easy to understand the operating mechanism of the traditional folktale contents once the envoy's position is the return of The Real responding to the repetitive impulse of the inferior subject.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.23 no.10
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• pp.36-44
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• 2009

This paper analyzes efficiency of photovoltaic(PV) tracking system using position solar algorithm(PSA). Solar location tracking system is needed for efficiently and intensively using PV system independent of environmental condition. PV tracking system of program method is presented a high tracking accuracy without the wrong operating in rapidly changing insolation by the clouds and atmospheric condition. Therefore, this paper analyzes efficiency of PV system using PSA algorithm for more correct position tracking of solar. Also, controlled altitude angle and azimuth angle by applied algorithm is compared with data of korea astronomy observatory. And this paper analyzes the tracking error and generation efficiency then proves the validity of applied algorithm.

• Journal of Institute of Control, Robotics and Systems
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• v.13 no.5
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• pp.434-443
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• 2007

Presently, the exploration of an unknown environment is an important task for thee new generation of mobile service robots and mobile robots are navigated by means of a number of methods, using navigating systems such as the sonar-sensing system or the visual-sensing system. To fully utilize the strengths of both the sonar and visual sensing systems. This paper presents a technique for localization of a mobile robot using fusion data of multi-ultrasonic sensors and vision system. The mobile robot is designed for operating in a well-structured environment that can be represented by planes, edges, comers and cylinders in the view of structural features. In the case of ultrasonic sensors, these features have the range information in the form of the arc of a circle that is generally named as RCD(Region of Constant Depth). Localization is the continual provision of a knowledge of position which is deduced from it's a priori position estimation. The environment of a robot is modeled into a two dimensional grid map. we defines a vision-based environment recognition, phisically-based sonar sensor model and employs an extended Kalman filter to estimate position of the robot. The performance and simplicity of the approach is demonstrated with the results produced by sets of experiments using a mobile robot.

• Proceedings of the SAREK Conference
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• 2009.06a
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• pp.847-852
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• 2009

Feedwater heaters of many nuclear power plants have recently experienced severe wall thinning damange, which will increase as operating time progresses. Several nuclear power plants in Korea have experienced wall thinning damage in the area around the impingement baffle inside feed-water heater installed downstream of the turbine extraction stream line. At that point, the extract steam from the turbine is two phase fluid at high temperature, high pressure, and high speed. Since it flows to reverse direction after impinging the impingement baffle, the shell wall of feedwater heaters may be affected by flow-accelerated corrosion. In this paper, to compare wall thinning range according to change entrance nozzle diameter and position with reference numerical analysis model's wall thinning range, various numerical analysis models applied. In case of changing diameter, four different diameter is applied. And a side of nozzle position, two different position-vertical type and parallel type-is applied. And then this paper describes operation of numerical analysis which is composed similar condition with real feed water heater. In conclusion, this study shows effective design for shall wall thinning by changing nozzle diameter and position.

• Proceedings of the Korean Society for Agricultural Machinery Conference
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• 2000.11b
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• pp.333-343
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• 2000

An automatic guidance system for combine was designed to harvest paddy rice by following a predetermined path. The automatic guidance system consisted of DGPS to locate position of combine, a gyro sensor system to measure heading angle, ultrasonic sensors to detect obstacles, a hydraulic system, microcomputer as a controller, and I/O interface system. Hydraulic cylinders and valves were installed to control movement of the combine. The heading angle and the position of the combine, and ultrasonic measurements from edge were used as the inputs of the controller. The operating position of hydraulic cylinder was determined as output of the controller. The automatic guidance system was evaluated at the 45-m straight path by changing the posture of the combine. The average RMS errors were 14.0 cm without offset and 15.0 cm with 1-m offset. The DGPS provided accurate position information within the limited error to guide the combine in the field. The results showed that the automatic guidance system could guide the combine autonomously in the paddy field when the posture of the combine was changed.

• Proceedings of the KIEE Conference
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• 1994.07a
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• pp.39-42
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• 1994

The application of speed or position control technique in AC drives demands accurate position and velocity feedback information. Generally, resolver and absolute encoders are used as a velocity or position sensor. But they increase cost and when the sampling frequency is faster than sensoer's output frequency we can't Set exact information. In order to solve this problem this thesis proposes a speed and a position observer design for Permanent-Magnet Synchronous Motors(PMSM) specialty in low speed drives. Most literatures on this topic design the observer based on the field_oriented d_q model. But in this thesis, a new approach to machine dynamics is proposed. Since it is difficult to design the observer using the nonlinear model, the machine model is here linearlized at the operating point. The observer designed is implemented by software using Intel's 8097 microprocessor and verifies the proper performance of observer by simulation and experiment.