• International Journal of Concrete Structures and Materials
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• v.10 no.1
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• pp.47-60
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• 2016

The objective of this study was to evaluate the capability of different strength-maturity models to account for the effect of the hydration heat on the in-place strength development of high-strength concrete specifically developed for nuclear facility structures under various ambient curing temperatures. To simulate the primary containment-vessel of a nuclear reactor, three 1200-mm-thick wall specimens were prepared and stored under isothermal conditions of approximately $5^{\circ}C$ (cold temperature), $20^{\circ}C$ (reference temperature), and $35^{\circ}C$ (hot temperature). The in situ compressive strengths of the mock-up walls were measured using cores drilled from the walls and compared with strengths estimated from various strength-maturity models considering the internal temperature rise owing to the hydration heat. The test results showed the initial apparent activation energies at the hardening phase were approximately 2 times higher than the apparent activation energies until the final setting. The differences between core strengths and field-cured cylinder strengths became more notable at early ages and with the decrease in the ambient curing temperature. The strength-maturity model proposed by Yang provides better reliability in estimating in situ strength of concrete than that of Kim et al. and Pinto and Schindler.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2010.05a
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• pp.153-157
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• 2010

As the recent economic downturn continues to undermine the profits of construction industry in Korea, it has become ever more pressing to improve productivity of the industry. Since construction site management manpower staffing plan has close bearing on the productivity of construction projects, it is essential to estimate and mobilize adequate number of resources as per conditions and characteristics of each construction site. However, there are no reference approaches in practice to provide baseline for site management manpower staffing plan or estimation of manpower requirement. Therefore, this study aims to examine factors affecting productivity that warrants first and foremost consideration in development of site management manpower staffing plan during the initial phase of building construction project by conducting survey on industry stakehoders with hands-on responsibilities in construction sites and analyzing their responses. Conclusions herein will provide basic inputs for subsequent studies on development of site management manpower staffing plan as per project characteristics.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.49 no.9
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• pp.618-625
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• 2000

Recently PWM inverters are widely utilized for many industrial applications e.g. high performance motor drive and PWM techniques are newly developed for an accurate output voltage. Among them space voltage vector PWM(SVPWM) inverter has high voltage ratio and low harmonics compared to the conventional sinusoidal PWM inverter. However output voltage of PWM inverter is distorted and has error duet o the conducting voltage drop of switching devices and the dead time that is inevitable to prevent the shoot-through phenomenon. This paper investigates 3-phase SVPWM inverter which has a new compensation method against dead time and voltage drop. Proposed algorithm calculates gate pulse periods which directly compensates the dead time and nonlinear voltage drop without modification of reference voltages. Direct compensation of gate pulse periods produces exact output voltage and does not need additional circuits. The propose algorithm is verified through the simulation and experiments.

• Proceedings of the KIEE Conference
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• 2002.07a
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• pp.551-553
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• 2002

The cubicle type GIS rated at 25.8kV has been designed and manufactured by Jinkwang E&C eacently with their own technologies and KERI's assistances. The C-GIS has been tested to check the design capability for reference before conducting the type test. The operating characteristics test, short time withstand current and peak withstand current test, basic short circuit test duty T60 for preconditioning test, cable charging current switching test, capacitor bank current switching test, basic short circuit test duty T100s and T100a, single phase earth fault test, double earth fault test has been conducted. The test results show that the design and the manufacturing of the C-GIS has an enough capability to pass through the type test except the occurrence of 2 NSDDs in the cable charging current switching test and the instability of opening time at the minimum operating voltage. The problems shown in the tests will be improved soon and the successful pass will be expected in the following type test.

• 제어로봇시스템학회:학술대회논문집
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• 1988.10a
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• pp.353-359
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• 1988

In this paper, the design and implementation of a multi-processor based die bonder machine for the semiconductor will be described. This is a final research results carried out for two years from June, 1986 to July, 1988. The mechanical system consists of three subsystems such as bonding head module, wafer feeding module, and lead frame feeding module. The overall control system consists of the following three subsystems each of which employs a 16 bit microprocessor MC 68000 : (i) supervisory control system, (ii) visual recognition / inspection system and (iii) the display system. Specifically, the supervisory control system supervises the whole sequence of die bonder machine, performs a self-diagnostics while it controls the bonding head module according to the prespecified bonding cycle. The vision system recognizes the die to inspect the die quality and deviation / orientation of a die with respect to a reference position, while it controls the wafer feeding module. Finally, the display system performs a character display, image display ans various error messages to communicate with operator. Lead frame feeding module is controlled by this subsystem. It is reported that the proposed control system were applied to an engineering sample and tested in real-time, and the results are sucessful as an engineering sample phase.

• ETRI Journal
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• v.39 no.3
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• pp.398-405
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• 2017

In this paper, an artificial stereo extension method that creates stereophonic sound from a mono sound source is proposed. The proposed method first trains deep neural networks (DNNs) that model the nonlinear relationship between the dominant and residual signals of the stereo channel. In the training stage, the band-wise log spectral magnitude and unwrapped phase of both the dominant and residual signals are utilized to model the nonlinearities of each sub-band through deep architecture. From that point, stereo extension is conducted by estimating the residual signal that corresponds to the input mono channel signal with the trained DNN model in a sub-band domain. The performance of the proposed method was evaluated using a log spectral distortion (LSD) measure and multiple stimuli with a hidden reference and anchor (MUSHRA) test. The results showed that the proposed method provided a lower LSD and higher MUSHRA score than conventional methods that use hidden Markov models and DNN with full-band processing.

• Journal of the Korean Society for Precision Engineering
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• v.13 no.2
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• pp.84-93
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• 1996

Non-destructive inspection techniques using laser have been broading their application areas as well as growing their measurement skills together with the rapid development of circumferential technology like fiber optics, computer and image processing. The ESPI technique is already on the stage of on-line testing with commercial products in developed country nations. Especially, this technique is expected to be applied to the nuclear industry, automobile and aerospace because it is proper for the vibration measurement and it can be applied to objects of a high temperature. This paper describes the use of the ESPI system for measuring vibration patterns on the reflecting objects. Using this system, high-quality Jo fringes for identifying mode shapes are displayed. A bias vibration is introduced into the reference beam to shift the Jo fringes so that fringe shift algorithms can be used to determine vibration amplitude. Using this method, amplitude fields for vibrating objects were obtained directly from the time-average interferograms recorded by the ESPI system.

• Natural Product Sciences
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• v.9 no.4
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• pp.256-259
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• 2003

The pet ether extract of Caesalpinia pulcherrima, leaves was studied for its antinociceptive, anti-inflammatory and antipyretic property. The extract at doses of 50 and 200 mg/kg, p.o., significantly (p<0.05) reduced the number of writhing induced by acetic acid and inhibited the late phase (20-30 min) in formalin test in mice. The extract failed to increase the pain threshold level in tail immersion test in mice. In carrageenan induced paw edema in rats and in acetic acid induced increase in vascular permeability test in mice, the extract (50-600 mg/kg, p.o.) failed to produce any significant activity. While in cotton pellet granuloma test, the extract at doses of 200 and 600 mg/kg (p.o.) significantly (p<0.05) reduced the granuloma formation and was comparable to reference drug, dexamethasone. In ethylpheylpropiolate ear edema test 0.5 mg and 1 mg/ear application of extract significantly (p<0.05) inhibited ear edema. In yeast induced hyperthermia in rats, the extract did not produce any reduction in temperature. The results suggest that the extract acts peripherally to produce analgesic action and anti-inflammatory activity through steroidal mechanism.

• 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.

• Nuclear Engineering and Technology
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• v.31 no.4
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• pp.423-431
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• 1999

A radiotracer technique has been developed to monitor the rotational movement of two piston rings in one cylinder during engine operation. The rings were labeled with two different kinds of radioisotopes, i.e. $^{60}$ Co and $^{192}$ Ir, for identification of the top ring from the second ring. The radiotracers were implanted in a small hole bored on the inner side of each piston ring. The rings were installed in a single cylinder hydrogen engine and three Nal scintillation detectors were mounted around the engine block to measure the gamma radiation. The angle of ring-gap orientation was determined from the radiation counts measured with the three detectors during engine operation. Two windows (upper window for $^{60}$ Co and lower window for $^{192}$ Ir) were set on each ratemeter to count radiation from the two isotopes separately. Procedure to convert the radiation counts to the position of the ring gap was established. With the software programmed with MS-Visualbasic, radiation counts were compared with the reference responses that were measured at angular intervals of 10$^{\circ}$for each piston ring in advance of the experiment. The result was used for the evaluation of the relationship between the orientation of ring-gaps and oil consumption. It was found that an increase in the oil consumption rate of a specific operation condition was closely related to the relative phase angle of the two piston rings.