• Proceedings of the KSME Conference
• /
• 2001.11a
• /
• pp.629-634
• /
• 2001

The construction of the elevated railway has led to concerns about the noise from trains, particularly as tracks often pass close to residential dwellings. One specific issue relates to the noise from trains on bridges. The wayside noise for the train was measured to get the basic data that can be used to prepare count measures for solving environmental noise problems. Noise levels were measured simultaneously at three points in various distances from the railroad and at four points classified by floor. In this paper we measure the wayside noise in elevated railway and noise of normal operation compare with operating under train engine idling condition and investigate effect of nearby-building induced by train operation.

• Journal of Korean Academy of Oral and Maxillofacial Radiology
• /
• v.15 no.1
• /
• pp.59-66
• /
• 1985

The Purpose of this study is to detect morphological changes of the maxilla following the operation of paranasal sinuses in the orthopantomogram. 1) The measurement of the angle set up by two reference lines which represent posterior aspect of the maxilla and skull base was made. 2) The mean angle in the post-operative patients showed significantly smaller than that in the normal subjects. 3) The forms of posterior aspect of maxilla were classified into 5 types. (flat, convex, concave, uneven and obliterated.) 4) In contrast with the convex type in the majority of normal subjects, approximately half of the post-operative patients showed the concave type. 5) These results may suggest that the superior part of the posterior aspect of the maxilla tend to depress following the operation of these paranasal sinuses.

• Korean Journal of Agricultural Science
• /
• v.38 no.1
• /
• pp.163-172
• /
• 2011

To provide the operation rule curve for suppling instream flow to urban stream from reservoir, the Soho reservoir with watershed area of 7.4 $km^2$ and total water storage of 2.58 $Mm^3$ was planned at the headwaters of the Daejeoncheon. Daily streamflow was simulated and using the simulated streamflow and desired instream flow, the operation rule curve by Senga method was drawn and evaluated through reservoir operation. Senga method is derived by accumulating the differences between streamflow and desired instream flow adversely. Water storages were simulated on a daily basis to supply urban instream flow from Soho reservoir, but the amount of supplying instream flow to urban stream was not nearly increased comparing with that of normal operation that does not used the rule curve. Thereafter the new simulation-based operation rule curve was derived and applied to supply instream flow from Soho reservoir. In normal operation, the amount of instream flow was shown to 15,000 $m^3$/d, but it was increased to 27,700 $m^3$/d in withdrawal limited operation using the new derived rule curve, in which the applicability of this rule curve was proved. Also comparing with the flow duration curves at station just before urban Daejeoncheon stream without and with upstream Soho reservoir, the 95th flow was decreased from 1.64 mm/d to 1.51 mm/d, and the 355th flow was increased from 0.17 mm/d to 0.30 mm/d. Monthly streamflows during October to March were increased from 10.6~24.1 mm to 24.1~34.0 mm with the increasing rate of 141~227%.

• Nuclear Engineering and Technology
• /
• v.27 no.3
• /
• pp.393-402
• /
• 1995

The structural analysis of the reactor coolant system mainly consist of too fields. The one is the static analysis considering the impact of pressure and temperature built up during normal operation. The other is the dynamic analysis to estimate the impact of postulated events such as the seismic loads or postulated branch line pipe breaks event. Since the most important goal of the RCS structural analysis is to prove the safety of the RCS during normal operation or postulated events, a widely proven theory having enough conservatism is adopted. The load occurring on the RCS during normal operation is considered as the basic design loading condition throughout whole plant life time. The most typical characteristic of the RCS during normal operation is the thermal expansion of the RCS caused by reactor coolant with high temperature and pressure. Therefore, the exact estimation on the thermal movement of the RCS is needed to get more clear understanding on the thermal movement behavior of the RCS. In this study, the general structural analysis concept and modeling method to evaluate the thermal movement of the RCS under the normal plant operation condition are presented. To discuss the validation of the suggested analysis, analysis results are compared with the measured data which ore referred from the standardized 1000 MWe PWR plant under construction.

• KSII Transactions on Internet and Information Systems (TIIS)
• /
• v.14 no.2
• /
• pp.738-756
• /
• 2020

The modular multiplication is the key module of public-key cryptosystems such as RSA (Rivest-Shamir-Adleman) and ECC (Elliptic Curve Cryptography). However, the efficiency of the modular multiplication, especially the modular square, is very low. In order to reduce their operation cycles and power consumption, and improve the efficiency of the public-key cryptosystems, a dual-field efficient FIPS (Finely Integrated Product Scanning) modular multiplication algorithm is proposed. The algorithm makes a full use of the correlation of the data in the case of equal operands so as to avoid some redundant operations. The experimental results show that the operation speed of the modular square is increased by 23.8% compared to the traditional algorithm after the multiplication and addition operations are reduced about (s² - s) / 2, and the read operations are reduced about s² - s, where s = n / 32 for n-bit operands. In addition, since the algorithm supports the length scalable and dual-field modular multiplication, distinct applications focused on performance or cost could be satisfied by adjusting the relevant parameters.

• Journal of Astronomy and Space Sciences
• /
• v.41 no.1
• /
• pp.43-60
• /
• 2024

Korea Pathfinder Lunar Orbiter (KPLO) is South Korea's first space exploration mission, developed by the Korea Aerospace Research Institute. It aims to develop technologies for lunar exploration, explore lunar science, and test new technologies. KPLO was launched on August 5, 2022, by a Falcon-9 launch vehicle from cape canaveral space force station (CCSFS) in the United States and placed on a ballistic lunar transfer (BLT) trajectory. A total of four trajectory correction maneuvers were performed during the approximately 4.5-month trans-lunar cruise phase to reach the Moon. Starting with the first lunar orbit insertion (LOI) maneuver on December 16, the spacecraft performed a total of three maneuvers before arriving at the lunar mission orbit, at an altitude of 100 kilometers, on December 27, 2022. After entering lunar orbit, the commissioning phase validated the operation of the mission mode, in which the payload is oriented toward the center of the Moon. After completing about one month of commissioning, normal mission operations began, and each payload successfully performed its planned mission. All of the spacecraft operations that KPLO performs from launch to normal operations were designed through the system operations design process. This includes operations that are automatically initiated post-separation from the launch vehicle, as well as those in lunar transfer orbit and lunar mission orbit. Key operational procedures such as the spacecraft's initial checkout, trajectory correction maneuvers, LOI, and commissioning were developed during the early operation preparation phase. These procedures were executed effectively during both the early and normal operation phases. The successful execution of these operations confirms the robust verification of the system operation.

• The Journal of the Korea institute of electronic communication sciences
• /
• v.18 no.5
• /
• pp.817-826
• /
• 2023

In this paper, a fault determination methodology based on an artificial neural network was proposed to protect the system from faults on the lines in the smart grid distribution system. In the proposed methodology, first, it was designed to determine whether there is a low impedance line fault (LIF) based on the magnitude of the current RMS value, and if it is determined to be a normal current, it was designed to determine whether a high impedance ground fault (HIF) is present using Normal/HIF classifier based on artificial neural network. Among repetitive DSP module-based algorithm verification tests, the normal/HIF classifier recognized the current waveform as normal and did not show reclosing operation for the cases of normal state current waveform simulation test where the RMS value was smaller than the minimum operating current value. On the other hand, for the cases of LIF where RMS value is greater than the minimum operating current value, the validity of the proposed methodology could be confirmed by immediately recognizing it as a fault state and showing reclosing operation according to the prescribed procedure.

• Journal of Advanced Navigation Technology
• /
• v.18 no.4
• /
• pp.319-324
• /
• 2014

Line operation safety audit (LOSA) is the proactive data collection system to capture the accident and serious incident caused by flight crew and is the safety management program for collecting threat error management (TEM) and crew resource management (CRM) during normal operations. The typically LOSA is written by hand, manages and archives the LOSA Observation Worksheet. But, this method is not easy to archive and ensure confidentiality of the LOSA worksheets. As we implemented the K-LOSA of the web-document type instead of the existing LOSA archive method and change the TEM category code. we yields to archive the efficient data management and confidentiality. In this paper, we introduce the LOSA and to configure the K-LOSA program.

• The Transactions of the Korean Institute of Electrical Engineers A
• /
• v.51 no.6
• /
• pp.290-295
• /
• 2002

The present assignment in installing the number of switches for distribution line was made on the basis of a normal feeder capacity 7,000kVA in KEPCO(Korea Electric Power Corporation), Korea. But the normal capacity is revised to 10000kVA in 1998. Even increasing limit of the operating capacity of the distribution lines enables us to give some benefit for the operation flexibility and investment cost of the distribution system. It is disadvantageous in the viewpoint of supply reliability. In distribution systems, switches are equipped to improve the reliability of distribution systems by minimizing the outage section due to fault and maintenance. Utility generally improves the reliability by minimizing the length of outage section, which is caused by fault and maintenance, through switch equipment on distribution system. In order to cope with the changes such as operation capacity, it is necessary to study whether the present criteria is reasonable or not, also to confirm whether the present criteria of installing switches in line is improved or not. In this study, we proposes the number of switch per feeder on the basis of present operation capacity in distribution system.

• Progress in Superconductivity and Cryogenics
• /
• v.22 no.4
• /
• pp.40-44
• /
• 2020

This paper describes the real operation of 2 kW class reverse-Brayton refrigeration system with neon as a working fluid. The refrigeration cycle is designed with operating pressure of 0.5 and 1.0 MPa at low and high pressure side, respectively. Compressor package consists of several helium scroll compressors witch are originally used for driving GM cryocooler. Three segments of plate heat exchanger are adopted to cover the wide temperature range and the refrigeration power is produced by turbo expander. The developed refrigeration system is successfully operated at its target temperature of 77 K. In experiments, all parameters such as pressure, temperature, mass flow rate and valve opening are measured to investigate characteristics during cool-down process and normal state. The difference between design and real operation is discussed with measured experimental data. At normal state of 77 K operation, the developed reverse-Brayton refrigeration system shows 1.83 kW at 68.2 K of cold-end temperature.