• 대한기계학회:학술대회논문집
• /
• 대한기계학회 2001년도 추계학술대회논문집A
• /
• 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.

• 치과방사선
• /
• 제15권1호
• /
• 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.

• 농업과학연구
• /
• 제38권1호
• /
• 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
• /
• 제27권3호
• /
• pp.393-402
• /
• 1995

원자로냉각재계통의 설계를 위한 구조해석 분야에는 원자로의 정상운전 과정에서 발생하는 유체의 온도와 압력의 변화에 의해 냉각재계통에 발생하는 정적하중해석, 지진과 가상적인 분지관 파단사고에 의해 냉각재계통에 발생하는 동적하중해석분야로 구분할 수 있다. 원자로냉가재계통의 구조해석은 원자력발전소의 안전성 화보 측면을 중시하여 해석시 충분한 여유도를 고려한 보수적인 해석 방법을 원용한다. 지진이나 가상적인 분지관 파단사고에 의한 냉각재계통의 구조해석은 사고시 냉각재계통의 안전성을 유지하는 방어적인 개념으로서 기기의 건전성을 확보하기 위하여 충분한 보수성과 안전여유가 해석시 고려된다 정상운전에 의해 냉각재계통에 발생하는 하중은 원자력 발전소의 상존하는 하중의 개념으로서 냉각재계통의 기본 설계 하중으로 인식된다. 특히 고온 고압의 유체로 인하여 발생하는 냉각재 계통의 열팽창 현상은, 정상운전 하중으로 인하여 나타나는 전형적인 거동으로서, 냉각재계통 구조해석 결과읜 중요한 지표로서 인식된다. 따라서 냉각재계통의 열팽창 현상을 정확히 예측하는 것은 원자로 냉각재계통 구조해석의 가장 중요한 목표중의 하나이다. 본 연구에서는 정상운전 하중에 의한 원자로 냉가재계통의 열팽창 거동을 해석하기 위한 냉각재계통의 모델링 방법과 해석 방법을 제시하였다. 해석 결과의 타당성을 검토하기 위하여 최근 건설 완료 단계에 돌입한 표준형 1000 MWe 급 가압경수로(Pn)의 고온기능시험 (Hot Function Test)과정에서 실측한 자료를 근거로 하여 원자로냉각재계통의 열팽창 거동 해석의 타당성을 입증코자 하였다.

• KSII Transactions on Internet and Information Systems (TIIS)
• /
• 제14권2호
• /
• 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
• /
• 제41권1호
• /
• 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.

• 한국전자통신학회논문지
• /
• 제18권5호
• /
• pp.817-826
• /
• 2023

본 논문에서는 스마트 그리드 배전 계통에서 선로상의 고장으로부터 계통을 보호하기 위한 인공 신경 회로망을 기반으로 하는 고장 판단 방법론을 제안하였다. 제안된 방법론에서는 먼저 전류 실효값 크기를 기반으로 일반 고장 여부를 판단하고 다음, 정상 전류로 판단되는 경우 인공 신경 회로망을 기반으로 하는 normal/HIF classifier를 이용하여 고 임피던스 지락 고장 여부를 판단하도록 설계하였다. 반복적인 DSP 모듈 기반 알고리즘 검증 시험들 중에서, 실효 값 크기가 최소 동작전류보다 작은 정상 전류 파형 시험인 경우에 normal/HIF classifier가 전류 파형을 정상상태로 인식하여 부 동작하였으며, 반면에, 저 임피던스 고장의 경우는 고장 상태로 인식하여 정해진 절차에 따라 재폐로 동작을 보임으로써 제안된 방법론의 유효성을 확인할 수 있었다.

• 한국항행학회논문지
• /
• 제18권4호
• /
• pp.319-324
• /
• 2014

LOSA(line operation safety audit)는 정상적인 운항 상태에서 운항 승무원이 발생할 수 있는 사고를 수집하기 위한 선제적 데이터 수집 방식으로 비행 중 발생하는 TEM(threat error management)과 CRM(crew resource management) 등을 수집하는 안전관리프로그램이다. 기존의 LOSA 기록 방식은 워크시트(worksheet) 에 관찰자가 직접 작성하여 자료를 보관하고 관리를 수행하였으나, 자료 보관의 어려움과 비밀 보장이 어려운 문제점이 있다. 기존의 LOSA 수집방식 대신 웹(web) 형태로 한국형 LOSA(K-LOSA)를 구현과 TEM 분류 코드를 변경하므로 효과적인 자료 관리 및 비밀 보장성을 확보하였다. 본 논문에서는 LOSA에 대하여 살펴보고 K-LOSA 프로그램의 구성을 소개한다.

• 대한전기학회논문지:전력기술부문A
• /
• 제51권6호
• /
• 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.

• 한국초전도ㆍ저온공학회논문지
• /
• 제22권4호
• /
• 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.