• Proceedings of the Korea Concrete Institute Conference
• /
• 2002.05a
• /
• pp.1023-1030
• /
• 2002

From the early 1980s, the New Austrian Tunnelling Method (NATM) has been developed as a one of the standard tunneling method in Korea. Approximately 10 years ago, wet-mix shotcrete with sodium silicate accelerator (waterglass) was introduced and widely used to tunnel lining and underground support. However, this accelerator had some disadvantages due to the decrease of long-term strength compared to plain concrete (without accelerator) and low quality of the hardened shotcrete. In order to compensate for these disadvantages, recently developed alkali-free accelerator has been successfully demonstrated in numerous projects and applications as a new material to make tunnels more durable and safer. An experimental investigation was carried out in order to verify the strength behavior of wet-mix Steel Fiber Reinforced Shotcrete (SFRS) with alkali-free accelerator. Compressive strength, flexural strength and equivalent flexural strength were measured by testing specimens extracted from the shotcrete panels. From the results, wet-mix SFRS with alkali-free accelerator exhibited excellent strength improvement compared to the conventional shotcrete accelerator.

• Nuclear Engineering and Technology
• /
• v.38 no.8
• /
• pp.779-784
• /
• 2006

The design, manufacturing process, and first operating test of a high power RF source for a proton accelerator are described. A klystron amplifier system has been developed for operation at 700 MHz, 1 MW and is composed of a triode type electron gun, six cavities, an RF output window, a beam collector, and an electromagnet. The prototype klystron was constructed and tested at a reduced duty to produce the designed output RF power.

• Proceedings of the Korean Vacuum Society Conference
• /
• 2013.02a
• /
• pp.547-547
• /
• 2013

This paper presents the understandings carried out for the installation of the hydrogen reservoir of the multi-gap pseudospark switch under developing for the accelerator applications. As a cold cold cathode switch, the pseudospark switch could replace the thyratron switch which has hot cathode and being used well currently in the high power field such as laser and accelerator applications. Especially in the klystron modulator, the key component is a switch which mostly defines the jitter and the instability of the modulator system. To get the less jitter and the instability, we need to find proper range of the pressure for the gas discharge inside gas switch. This could be achieved by the understanding of the characteristic of the nonevaporable getter (NEG) which is used as a hydrogen reservoir for the switch. Therefore we verified the characteristics of the NEG (St 172, Saes) and its installation in the switch. Finally we controlled the getter to find best pressure point for the pseudospark switch.

• International Area Studies Review
• /
• v.22 no.4
• /
• pp.167-186
• /
• 2018

In this paper try to derive some implications through comparative studies of accelerator in Korea and US centering on accelerator process model. In addition, the concept of accelerator is defined comprehensively through the existing literature study, and the accelerator program is focused on the accelerator process model. In the study, three Korea and America accelerators were selected and analyzed as follows. First, we discussed the definition of the accelerator, the configuration program, and the differences with existing organizations. Second, after selecting three representative companies among Korean and American accelerators, history, programs, achievements, characteristics, and limitations were derived. Third, based on the existing literature research, we compared the differences in appearance and performance between the six Korean and US accelerator companies using the table. Finally, the limitations and implications of domestic accelerators are described.

• Journal of The Korean Society of Agricultural Engineers
• /
• v.46 no.3
• /
• pp.65-72
• /
• 2004

Modern underground and tunnel works that the wet type shotcrete is getting widely designed and applied in a large scale project. Further to its applications, the needs of improving the performance of the shotcrete, such as new and developed additives and accelerators fur increasing the performance of shotcrete, become the most important issue in the field. The main objective of this study evaluated to performance of steel fiber reinforced shotcrete using alkali free based accelerator for the durability and high quality of shotcrete. The major test variables are accelerator type and its dosage. One type silicate based accelerator and one type aluminate based accelerator and one type alkali free based accelerator were used. The dosage of accelerators is determined by the manufactures and laboratory test condition. Compressive strength test results showed that the dosage of silicate and aluminate based accelerators caused reduction of mechanical properties of shotcrete. Compressive strength of alkali free based accelerator is more stable than of silicate and aluminate based accelerators. Also, according to the compressive strength and flexural test results, it was found that steel fiber reinforced shotcrete used alkali free based accelerator could attain significant improvement in the mechanical and flexural performance.

• Proceedings of the KIPE Conference
• /
• 2012.07a
• /
• pp.172-173
• /
• 2012

포항가속기 연구소에서는 4세대 가속기의 전자를 가속시키기 위해서 100ppm(0.01%) 이하의 고전압 안정도를 가진 200MW 펄스 모듈레이터가 요구된다. 그러므로 본 연구소에서는 고전압 안정도를 가진 고정밀 고전압 CCPS를 일반 CCPS와 병행하여 산업체와 함께 공동 개발을 진행하였다. 개발된 일반 CCPS의 사양은 50 kV, 30 kJ/sec, 600mA, 1000ppm이하이고, 고정밀 CCPS의 사양은 50 kV, 5 kJ/sec, 100mA, 100ppm이하이다. 본 논문에서는 CCPS의 개발 및 실제 모듈레이터에 설치하여 시험한 결과를 발표하고자 한다.

• Proceedings of the KIEE Conference
• /
• 1992.07b
• /
• pp.928-930
• /
• 1992

The design beam energy of PLS(Pohang Accelerator Laboratory) Linac is 2Gev. The linac employs total 11 units of modulators and klystrons. The maximum peak output powers of the modulators are 200MW (400kV, 500A, 4.4$\mu$S flat-top, 800$\Omega$ load) to drive the klystrons which have the peak microwave power of 80MW. Prior to the development of the 200MW modulators, a prototype 150MW modulator has been constructed and tested. We have achieved output pulses of 350kV, 420A and 3.5$\mu$S flat-top with 840$\Omega$ water load. In this article, the test results and computer simulations of charging, De-Q'ing, and discharging are presented.

• Proceedings of the Korea Concrete Institute Conference
• /
• 2004.11a
• /
• pp.253-256
• /
• 2004

Recently, construction works of scale are getting larger with economic growth. Shotcreting is one of major processes in tunnels construction. Accelerator is used in tunnel and underground structures to ensure early strength of shotcrete. Silicate based accelerator and aluminate based accelerator is getting widely in the field. But these accelerators have many problems due to decesase of long-term strength and low quality of the hardened shotcrete. in order to solve these problems, recently developed powder types cement mineral accelerator. In this study, we tested chloride permeability, freezing and thawing and accelerated carbonation of shotcrete. As a result of the test, wet-mixed shotcrete with powder types cement mineral accelerator exhibited durability improvement compared to the conventional shotcrete accelerator.

• Proceedings of the KIEE Conference
• /
• 2006.07c
• /
• pp.1562-1563
• /
• 2006

고출력 마이크로웨이브의 펄스 전원으로 PFN Marx 펄스 전원공급장치를 설계 및 제작하였다. PFN Marx는 커패시터와 인덕터 그리고 스파크 갭과 전원을 공급하는 전원공급장치와 전류 제한용 저항 또는 인덕터로 구성하여 제작을 하였다. 여기에 사용하는 스파크 갭 스위치는 개스를 채우는 방식으로 개스의 압력을 조정하여 스위치의 스위칭 전압을 조정하여 준다. PFN Marx는 커패시터와 인덕터가 직병렬로 구성이 되며 펄스폭과 PFN의 임피던스를 결정하는 중요한 요소이다. PFN Marx 펄스 전원공급장치를 시뮬레이션 및 제작하여 시험을 할 예정이며 요구되는 사양은 전압 수십 kV, 펄스 폭 수백 ns이다. 본 논문에서는 PFN Marx 펄스전원장치의 설계 및 시험에 대하여 고찰하고자 한다.

• Proceedings of the KIEE Conference
• /
• 2007.07a
• /
• pp.1599-1600
• /
• 2007

The DTL water skid cooling system and Resonant Control Cooling Systems (RCCS) will employ a control system that can be operated by a local, programmable logic controller (PLC), interfaced through a touch screen interface, mobile alarm SMS server system, or it can be operated through the PEFP global control system network. The RCCS is implemented using Experimental Physics and Control System (EPICS) based hardware and software and is integrated with other networked PEFP EPICS systems. This presentation discusses the features of the local control system.