서종환 교수

A bstract The Reactor Experiment for Neutrino Oscillation (RENO) experiment has been taking data using two identical liquid scintillator detectors since August 2011. The experiment has observed the disappearance of reactor neutrinos in their interactions with free protons, followed by neutron capture on hydrogen (n-H). Based on 1500 live days of data taken with 16.8 GW th reactors at the Hanbit Nuclear Power Plant in Korea, the near (far) detector observes 567690 (90747) electron antineutrino ca

Accelerated lifetime prediction is the key technology to assure the safety and reliability of rubber products in automotive components. In the present study, carbon black (CB), which has been a conventional reinforcing filler in the rubber industry, was partially replaced by graphene in natural rubber (NR) composite system. Due to the superior intrinsic thermal conductivity of graphene, it is getting much attention to reduce heat build-up problem of vibration mount for longer lifetime in its dem

The JSNS<SUP>2</SUP> (J-PARC Sterile Neutrino Search at J-PARC Spallation Neutron Source) experiment aims to search for neutrino oscillations over a 24 m short baseline at J-PARC. The JSNS<SUP>2</SUP> inner detector is filled with 17 tons of gadolinium(Gd)-loaded liquid scintillator (LS) with an additional 31 tons of unloaded LS in the intermediate γ-catcher and an optically separated outer veto volumes. A total of 120 10-inch photomultiplier tubes observe the scintillating optical photons and e

The properties of neutrinos are not well known because they weakly interact with surrounding matter. Recently, several interesting results and phenomena have been measured using reactor neutrinos. Although there are various types of detectors that detect neutrino signals, they generally use photomultiplier tubes (PMTs) to collect data. In particular, signals obtained from each PMT surrounding a detector are used to reconstruct a vertex of an incident neutrino in the detector. However, if a numbe

The Reactor Experiment for Neutrino Oscillation (RENO) experiment has been taking data using two identical liquid scintillator detectors of 44.5 tons since August 2011. The experiment has observed the disappearance of reactor neutrinos in their interactions with free protons, followed by neutron capture on hydrogen. Based on 1500 live days of data taken with 16.8 GW$_{th}$ reactors at the Hanbit Nuclear Power Plant in Korea, the near (far) detector observes 567690 (90747) electron antineutrino c

제지폐기물 등 목재에서 유래한 리그닌은 비식량계 바이오매스이나 열안정성이 부족하여 사용이 제한적이었지만, 리그닌 폴리에스터(lignin polyester, LigPS)는 고온가공이 가능하도록 합성되어 복합재료 기지재로서 활용이가능해 졌다. 황마섬유(jute fiber, JF)/폴리프로필렌(polypropylene, PP) 복합재료에 LigPS와 몬모릴로나이트(montmorillonite, MMT) 함량을 변화시키며 첨가하여 특성변화를 연구했다. LigPS는 복합재료에 20 wt%까지 첨가가 가능하였고 5%만 첨가하여도 인장강도와 탄성률이 증가였고, JF와 계면에서는 상용성을 보였고 수분흡수 실험에서는 내수성도 향상되었다. 또한 여기에 MMT는 5 wt% 투입했을 때 탄성률이 50% 증가하는 등 기계적 물성이크게 증가였다. 이로부터 JF/PP 복합재료에 LigPS와 MMT로 복합화하여 바이오매스 함량을 증가시키면서 성능도변화시켜 친환경 나노복합소재로의 활용 가능성을 확인하였다.

전기자동차 시장이 성장함에 따라 배터리 효율을 증가시키기 위해 차량 경량화 이슈가 대두되고 있다. 이에 전기자동차 배터리 모듈을 보호하는 배터리 모듈 커버를 기존 알루미늄 소재에서 알루미늄 대비 절반 수준의 무게를 가지는 고강도/고내열성 고분자 복합소재로 대체하고자 한다. 또한 복잡한 형상에 대한 제약이 없고, 다품종 소량생산에 유리한 3D 프린팅 기술을 접목하여 기술 변화가 빠른 초기 전기자동차 시장에 대응하고자 한다. 복합소재 역학에 기반하여 압출기를 통해 가공한 단섬유 GF(glass fiber)/PC(polycarbonate) 복합소재 내 유리섬유의 임계길이(critical length)가 453.87 μm임을 도출하였고, 사이드 피딩(side feeding) 방식의 가공법을 택함으로써 기존 365.87 μm이었던 잔류섬유길이를 향상시킴과 동시에 분산성을 향상시켰다. 이에 30 wt%의 GF가 함유된 GF/PC 복합소재로 인장강도(tensile strength) 135 MPa

Graphene-incorporated polymer composites have been demonstrated to have excellent mechanical and electrical properties. In the field of graphene-incorporated composite material synthesis, there are two main obstacles: Non-uniform dispersion of graphene filler in the matrix and weak interface bonding between the graphene filler and polymer matrix. To overcome these problems, we develop an in-situ polymerization strategy to synthesize uniformly dispersed and covalently bonded graphene/lignin compo

As packaging technologies are demanded that reduce the assembly area of substrate, thin composite laminate substrates require the utmost high performance in such material properties as the coefficient of thermal expansion (CTE), and stiffness. Accordingly, thermosetting resin systems, which consist of multiple fillers, monomers and/or catalysts in thermoset-based glass fiber prepregs, are extremely complicated and closely associated with rheological properties, which depend on the temperature cy

Ultrasonic nondestructive testing is important for monitoring the structural integrity of dissimilar metalwelds (DMWs) in pressure vessels and piping in nuclear power plants. However, there is a low probabilityof crack detection via inspection of DMWs using ultrasonic waves because the grain structures(grain orientations) of the weld area cause distortion and splitting of ultrasonic beams propagating inanisotropic media. To overcome this issue, the grain orientation should be known, and a precis

In this study, we fabricated a parallelly connected Li-ion battery/supercapacitor hybrid cell to combine the advantageous characteristics of Li-ion battery and supercapacitor, high energy density and high power density,respectively, and investigated its discharging characteristics over a wide temperature range from -40 to 25°C. At the initial state of discharging of the hybrid cell, the power was mostly provided by the supercapacitor and then the portion of the Li-ion battery was gradually incre

This paper describes in detail the uncertainties due to several factors that may affect the direction vector of a reactor neutrino in a liquid scintillation detector. The reactor neutrino direction vector was reconstructed through a charge weighting method. The paper simulates the response of gadolinium-loaded, liquid scintillator detector to reactor electron anti-neutrinos. The reaction is based on neutrino capture on hydro-genic protons of inverse beta decay process in the scintillator. A Cher

As device miniaturization in microelectronics is currently requested in the development of high performance device, which usually include highly-integrated metal-polyimide multilayer structures. A redistribution layer (RDL) process is currently emerging as one of the most advance fabrication techniques for on-chip interconnect and packaging. One of the major issues in this process is the poor adhesion of the metal-polyimide interfaces particularly in flexible circuit boards due to the flexibilit

탄소나노튜브는 우수한 기계적 특성으로 인해 주목받고 있으며, 다양한 산업 분야로의 잠재적 활용성을 갖는 고강도/고강성의 나노복합재료를 설계/제작하기 위한 다양한 연구가 이루어 지고 있다. 본논문에서는 다중벽 탄소나노튜브를 이용한 강화 복합재료를 효과적으로 설계하고, 기계적 물성을 예측/평가하기 위한 미시역학적 해석 방법 연구를 수행하였다. 이를 위해 먼저 대표체적요소 모델을 설계하고 이를 이용한 유한요소 해석을 통해서 강화 복합재료의 기계적 물성을 평가하였다. 특히 MWCNT 의각 형상인자에 따른 복합재료의 탄성계수 변화를 예측하고, 각 인자들의 영향을 정성적으로 평가하였다. 더불어 형상인자들의 복합적 조건에서의 탄성계수에 대한 영향 평가도 수행하였다.