• Environmental and Resource Economics Review
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• v.15 no.5
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• pp.799-826
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• 2006

Combining recent advances in causal flows with time series analysis, relationships among eight North American natural gas spot market prices are examined. Results indicate that price discovery tends to occur in excess demand regions and move to excess supply regions. Across North America, the U.S. Midwest region represented by Chicago spot market is the most important market for price discovery. The Ellisburg-Leidy Hub in Pennsylvania is important in price discovery, especially for markets in the eastern two-thirds of the U.S. Malin Hub in Oregon is important for the western markets including the AECO Hub in Alberta, Canada.

• Journal of the Korea Society of Computer and Information
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• v.3 no.1
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• pp.25-34
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• 1998

There are two major method for expressing parallelim in functional languages. The one is the strictness analysis and the other the annotation. The strictness analysis is a method that a compiler detects parallelism and expresses the detected information in the object program. The annotation is a method that a programmer detects parallelism and expresses in the source program. This study is on the annotation and is aimed at construction of a translator for a functional language which has an annotation syntax. The translator translates a source program to enriched lambda-calculus graphs. The translator is implemented in C using compiler development tools such as YACC and Lex, under UNIX environments. In this paper we present the design and implementation techniques for developing the front-end of the translator.

• Journal of Korea Water Resources Association
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• v.36 no.3 s.134
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• pp.481-494
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• 2003

Flow through the culvert is very complex depending on the characteristics of hydraulic conditions. A design method using a monograph is normally employed due to the wide range of flow characteristics and the difficulty of calculating inlet water depth. The present study suggests the method for determining the inlet water depth of box culvert using Bernoulli's equation. By employing the explicit equation of inlet water depth, a standard design method of box culvert is developed for a wide range of flow characteristics. Explicit solution techniques are proposed to determine the width and height, slope and discharge of box culvert.

• Journal of Radiation Industry
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• v.8 no.1
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• pp.49-52
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• 2014

Kenaf fibers have excellent properties and possess the potential to be outstanding reinforcing fillers in cement. The grafting of poly(ethylene glycol) methacrylate (PEGMA) to the kenaf fibers is important in improving the compatibility between the fibers and the cement. PEGMA was grafted onto kenaf fibers using gamma-ray radiation. The radiation dose ranged from 20 to 60 kGy, and the dose rate was $10kGy\;h^{-1}$. The degree of grafting increased with increased radiation doses. FT-IR analysis revealed an increase in PEGMA content after gamma-ray radiation induced grafting, further evincing the attachment of PEGMA to the kenaf fibers. The mechanical properties of the gamma-ray grafted kenaf fiber/cement composites were superior to those of the ungrafted kenaf fiber/cement specimens.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.38 no.6
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• pp.831-838
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• 2018

This paper presents a method to estimate the flow discharge in a backwater affected river junction. First, unsteady HEC-RAS model was simulated and calibrated using 2 recent real flood and then HPG (Hydraulic Performance Graph) was created by plotting the relationship between upstream and downstream stages and discharge in the reach and performing kriging interpolation. During a flood, the discharge through the reach can be estimated based on the stages at its ends and the developed HPG. These discharge data were in good agreement with the automatic discharge measurements such as ADVM. This study could provide an economical and practical method for estimating discharge in a junction with a high hysteresis of stage-discharge relationships.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.26 no.5
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• pp.471-482
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• 2015

In this paper, design and implementation of the 94 GHz Gunn oscillator and the evaluation of the maximum power of the Gunn diode used in the oscillator are presented. The 94 GHz Gunn oscillator is used InP Gunn diode and designed employing a WR-10 waveguide. The designed oscillator is fabricated through machining and its performance is measured. The fabricated oscillator shows an oscillation frequency of 95 GHz, output power of 12.64 dBm, and phase noise of -92.7 dBc/Hz at 1 MHz offset frequency. To evaluation the maximum power of the InP Gunn diode used in oscillator, the oscillator structure is modified to a structure having a diaphram. The height of thick diaphram which is used in the oscillator is varied. As a result, an oscillator has several different load impedances, which makes it possible to plot $G_L-V^2$ plot at the post plane. Using the $G_L-V^2$ plot, the maximum power of used Gunn diode including post is computed to be 16.8 dBm. Furthermore using the shorted and zero bias Gunn diode, the post loss used for DC biasing can be computed. Using the two losses, The maximum power of a InP Gunn diode is computed to be 18.55 dBm at 95 GHz. This result is close to a datasheet.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.26 no.3
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• pp.469-478
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• 2022

This paper contains the results of developing smart devices and applications to monitor the load power of the industrial manufacturing machine and evaluate its performance. The smart devices in this paper are divided into two functionalities, which are collecting load power along with operating environment data of industrial manufacturing machines and transmitting the data to servers. Load power data collected from the smart devices are uploaded to MariaDB inside the Amazon Web Service (AWS) server. Using the RESTFul API, the uploaded power data can be retrieved and shown on the web and mobile application in the form of a graph to provide monitoring capability. To evaluate the performance of the developed system, the response time from MariaDB to web and mobile applications was measured. The results is ranging from 0.0256 to 0.0545 seconds in a 4G (LTE) network environment and from 0.6126 to 1.2978 seconds in a 3G network environment, which is considered a satisfactory result.

• Journal of radiological science and technology
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• v.30 no.2
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• pp.105-111
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• 2007

This study is to calculate the proper angle for the optimal image of PNS Water's view on children, comparing and analyzing the PNS Water's projection angles between children and adults at every age. This study randomly selected 50 patients who visited the Medical Center from January to May in 2005, and examined the incidence path of central ray, taking a PNS Water's and skull trans-Lat. view in Water's filming position while attaching a lead ball mark on the Orbit, EAM, and acanthion of the patients's skull. And then, we calculated the incidence angles(Angle A) of the line connected from OML and the petrous ridge to the inferior margin of maxilla on general(random) patients's skull image, following the incidence path of central ray. Finally, we analyzed two pieces of the graphs at ages, developing out the patients' ideal images at PNS Water's filming position taken by a digital camera, and calculating the angle(Angle B) between OML and IP(Image Plate). The angle between OML and IP is about $43^{\circ} in 4-years-old children, which is higher than $37^{\circ}, as age increases the angle decreases, it goes to $37^{\circ} around 30 years of age. That is similar result to maxillary growth period. We can get better quality of Water's image for children when taking the PNS Water's view if we change the projection angles, considering maxillary growth for patients in every age stage.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• fall
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• pp.290-293
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• 2021

In this paper, we implement a learning efficiency verification system to inspire learning motivation and help improve concentration by detecting the situation of the user studying. To this aim, data on learning attitude and concentration are measured by extracting the movement of the user's face or body through a real-time camera. The Jetson board was used to implement the real-time embedded system, and a convolutional neural network (CNN) was implemented for image recognition. After detecting the feature part of the object using a CNN, motion detection is performed. The captured image is shown in a GUI written in PYQT5, and data is collected by sending push messages when each of the actions is obstructed. In addition, each function can be executed on the main screen made with the GUI, and functions such as a statistical graph that calculates the collected data, To do list, and white noise are performed. Through learning efficiency checking system, various functions including data collection and analysis of targets were provided to users.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.23 no.4
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• pp.86-91
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• 2009

Indirect Touch switch which detects the change of capacitance around the electrode of QT113H chip from QPROX is designed and assembled. Sensitivity analysis of dielectric materials which prevents electrodes from direct touch is performed and the results are displayed in tables and graphs. Glass, acryl, and MDF is used to insulate the electrode and to measure the operating sensitivity of indirect touch switch. While the difference of permittivity of the dielectric materials are large, it is confirmed that the operating sensitivity of each dielectric materials are not so large as the differences of those of dielectric materials.