Simulations on the Fast-beam Ion Instability at the PLS

진현창,윤무현,신승환,I. Hwang,K. Ohmi 한국물리학회 2011 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.59 No.22

The fast-beam ion instability is a significant issue in an electron storage ring. In this paper, a weak-strong simulation code is used to simulate the fast-beam ion instability at the in-vacuum undulators of the Pohang Light Source (PLS) and the PLS-II. The growth time of the vertical oscillation amplitude is calculated for various vacuum pressures. Above the threshold vacuum pressure, the vertical oscillation amplitude exceeds the vertical beam size. The effect of a feedback system is investigated and shows that bunch-by-bunch feedback of 50 turns is effective in suppressing the growth of the vertical oscillation amplitude.

Designing of the Low Energy Beam Lines with Achromatic Condition in the RAON Accelerator

진현창,장지호,전동오 한국물리학회 2017 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.70 No.1

The RAON accelerator has been built to create and accelerate stable heavy-ion beams and rare isotope beams. The stable heavy-ion beams are generated by the superconducting electron cyclotron resonance ion source and accelerated by the low energy superconducting linac SCL1. The beams accelerated by the SCL1 are re-accelerated by the high energy superconducting linac SCL2 for the generation of rare isotope beams by using the in-flight fragmentation system or are put to use in the low energy experimental halls, which include the neutron science facility and the KOrea Broad acceptance Recoil spectrometer and Apparatus after having passed through the low energy beam lines which have long deflecting sections. At the end of each beam line in the low energy experimental halls, the beams should meet the targets of the two facilities with the specific requirements satisfied. Namely, if the beam is to be sent safely and accurately to the targets and simultaneously, satisfy the requirements, an achromatic lattice design needs to be applied in each beam line. In this paper, we will present the lattice design of the low energy beam lines and describe the results of the beam dynamics simulations. In addition, the correction of the beam orbit, which is distorted by machine imperfections, will be discussed.

지상파 TV방송의 디지털전환을 위한 지자체 및 CATV방송사의 역할 : K지역 CATV방송사의 추진사례를 중심으로

진현창,윤한성 경성대학교 산업개발연구소 2011 산업혁신연구 Vol.27 No.4

최근 세계적으로 가장 중요한 방송정책의 하나로 평가되고 있는 지상파 TV방송의 디지털전환은 우리나라에서도 2012년 12월 31일 04:00시를 기하여 개시되는 것으로 계획되어 있다. 디지털 TV방송의 원활한 제공이 정부의 의지만으로 쉽지 않으며, 디지털방송 전환의 실질적인 주체가 방송사 및 유료방송사업자라는 점에서 공공-민간 협력은 매우 중요하다. 또한 TV방송의 시청자가 여러 지역에 산재하는 특성을 가지고 있으므로, 지역사회의 협력체계가 디지털전환의 성패에 중요한 요인으로 간주되고 있다. 이러한 측면에서 성공적인 디지털전환을 위한 지역의 문제점을 해결해 가는 것이 필요하며, 지역의 디지털전환에 중심역할을 할 수 있는 지자체와 방송사업의 전문성을 갖춘 CATV방송사의 역할과 협조방식은 중요한 접근방식이라고 할 수 있다. 본고에서는 이와 같은 디지털전환의 지역적 협력체계와 특성을 고려하여, 지자체 및 지역CATV방송사의 역할을 중심으로 지역의 디지털전환 추진전략 사례를 경남 서부지역(K지역)을 사업영역으로 하는 CATV방송사의 입장에서 정리하였다. 또한 K지역 시청자 표본을 통해 지자체와 지역 CATV방송사의 협력적 역할에 대한 가능한 효과를 정리해보았다. 이는 현재 진행 중인 디지털전환에 필요한 지자체 및 지역 CATV방송사의 역할정립, 관련한 정부정책의 수립에도 반영할 수 있을 것이다. The digital transition of terrestrial TV broadcasting, which is one of the most important worldwide broadcasting policies recently, is planned to be started from 31th Dec., 2012 in Korea. Considering the concept of ‘free and universal service’ on terrestrial broadcasting, providing digital broadcasting service only with the intention of government may not be carried out smoothly. For the digital transition, a pay-broadcasting company may play critical roles as a substantial main participant and the cooperation system between public and commercial organizations is important. Moreover, as TV viewers are scattered over regions, the cooperation system of each regional society is considered as a success factor for the digital transition. In this opinion, the regional CATV company with regional information and specialty on regional broadcasting can play roles for the digital transition with the support of regional governments. This paper addresses such roles of the K-region CATV company and cooperation between regional governments and CATV companies.

Beam dynamics at the main LEBT of RAON accelerator

진현창,장지호 한국물리학회 2015 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.67 No.8

The high-intensity rare isotope accelerator (RAON) of the Rare Isotope Science Project (RISP) in Daejeon, Korea, has been designed to accelerate multiple-charge-state beams. The ion beams, which are generated by using an electron cyclotron resonance ion source (ECR-IS), will be transported through the main low energy beam transport (LEBT) system to the radio frequency quadrupole (RFQ). While passing the beams through the LEBT, we should keep the transverse beam size and longitudinal emittance small. Furthermore, the matching of required twiss parameter at the RFQ entrance will be performed by using electro-static quadrupoles at the main LEBT matching section which is from the multi-harmonic buncher (MHB) to the entrance of the RFQ. We will briefly review the new aspects of the main LEBT lattice, and the beam matching at the main LEBT matching section will be presented. In addition, the effects of various errors on the beam orbit and the correction of a distorted orbit will be discussed.

Electron Cloud Instability at Cser-TA

진현창,윤무현,K. Ohmi 한국물리학회 2010 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.56 No.61

The electron cloud instability (ECI) is a signi¯cant issue at the International Linear Collider Damping Ring (ILC-DR) which can limit the performance. A new lattice called Cesr-TA has been developed from the Cornell Electron Storage Ring (CESR) for ILC-DR research. We investigate beam instabilities caused by the electron cloud in the Cesr-TA lattice. We simulate the interaction of a bunch and a cloud by using the uniform beta function lattice and the real lattice models of Cesr-TA. The simulation results are favorably compared with the analytic estimates.

Error Tolerance Studies for the Superconducting Linac of RAON

장희재,진현창 한국물리학회 2015 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.67 No.8

RAON, an ion accelerator, is planned in Daejeon, Korea, by the Rare Isotope Science Project. RAON has three linear accelerators, and they will accelerate various stable ions such as uranium, xenon, oxygen and rare isotopes from the isotopes separation on-line system. The linear accelerators of the RAON adopted superconducting cavities and a warm quadrupole doublet structure. Because the target beam power is 400 kWfor the uranium beam, the small beam loss in the linear accelerators can be concluded to the radiation damage to the devices in this region. As a result, estimating the allowable alignment and radio-frequency errors for the RAON linear accelerator is one of the important topics for this project. In this paper, the beam dynamics simulation results, including such errors, will be described.

중이온 가속기 RAON의 빔시운전

장지호(Ji-Ho JANG),전동오(Dong-O JEON),진현창(Hyunchang JIN),김형진(Hyungjin KIM) 한국물리학회 2024 물리학과 첨단기술 Vol.33 No.5

Tumor Stage-Related Role of Radiotherapy in Patients with an External Auditory Canal and Middle Ear Carcinoma

최진현,김세헌,고윤우,최은창,이창걸,금기창 대한암학회 2017 Cancer Research and Treatment Vol.49 No.1

Purpose The purpose of this study was to evaluate the clinical outcomes of patients treated with radiotherapy (RT) for a carcinoma of the external auditory canal (EAC) and middle ear. Materials and Methods The records of 32 patients who received RT from 1990 to 2013 were reviewed retrospectively. The Pittsburgh classification was used to stage all the cancers (early stage, T1/T2 [n=12]; advanced stage, T3/T4 or N positive [n=20]). Twenty-one patients (65.6%) were treated with postoperative RT and 11 patients (34.4%) were treated with definitive RT. The median radiation doses for postoperative and definitive RT were 60 Gy and 64.8 Gy, respectively. Chemotherapy was administered to seven patients (21.9%). Results The 5-year overall survival and disease-free survival rates for all patients were 57% and 52%, respectively. The disease control rates for the patients with early stage versus advanced stage carcinoma were 55.6% (5/9) and 50% (6/12) in the postoperative RT group and 66.7% (2/3) and 37.5% (3/8) in the definitive RT group, respectively. Overall, 15 cases (14 patients, 46.7%) experienced treatment failure; these failures were classified as local in four cases, regional in one case, and distant in 10 cases. The median follow-up period after RT was 51 months (range, 7 to 286 months). Conclusion Patients with early stage carcinoma achieved better outcomes when definitive RT was used. Advanced stage carcinoma patients experienced better outcomes with postoperative RT. The high rate of distant failure after RT, with or without surgery, reflected the lack of a consensus regarding the best therapeutic approach for treating carcinoma of the EAC and middle ear.