복합재료용 탄소섬유의 특성

임연수(Yun Soo Lim) 한국고분자학회 1997 고분자 과학과 기술 Vol.8 No.2

탄소나노튜브 강화 탄소 복합재의 제조와 물성 평가

임연수 ( Yun Soo Lim ),김태완 ( Tae Wan Kim ),성재훈 ( Jae Hoon Sung ) 대한금속·재료학회 2006 재료마당 Vol.19 No.6

양성자 조사가 316 스테인리스강의 미세조직과 표면산화 특성에 미치는 영향

임연수 ( Yun-soo Lim ),김동진 ( Dong-jin Kim ),황성식 ( Seong Sik Hwang ),최민재 ( Min Jae Choi ),조성환 ( Sung Whan Cho ) 한국부식방식학회(구 한국부식학회) 2021 Corrosion Science and Technology Vol.20 No.3

Austenitic 316 stainless steel was irradiated with protons accelerated by an energy of 2 MeV at 360 ℃, the various defects induced by this proton irradiation were characterized with microscopic equipment. In our observations irradiation defects such as dislocations and micro-voids were clearly revealed. The typical irradiation defects observed differed according to depth, indicating the evolution of irradiation defects follows the characteristics of radiation damage profiles that depend on depth. Surface oxidation tests were conducted under the simulated primary water conditions of a pressurized water reactor (PWR) to understand the role irradiation defects play in surface oxidation behavior and also to investigate the resultant irradiation assisted stress corrosion cracking (IASCC) susceptibility that occurs after exposure to PWR primary water. We found that Cr and Fe became depleted while Ni was enriched at the grain boundary beneath the surface oxidation layer both in the non-irradiated and proton-irradiated specimens. However, the degree of Cr/Fe depletion and Ni enrichment was much higher in the proton-irradiated sample than in the non-irradiated one owing to radiation-induced segregation and the irradiation defects. The microstructural and microchemical changes induced by proton irradiation all appear to significantly increase the susceptibility of austenitic 316 stainless steel to IASCC.

니켈기 합금 Alloy 690에서 파형입계 특성에 관한 연구

임연수 ( Yun Soo Lim ),김동진 ( Dong Jin Kim ),황성식 ( Seong Sik Hwang ) 대한금속재료학회(구 대한금속학회) 2014 대한금속·재료학회지 Vol.52 No.9

A study on grain boundary serration in the Ni-based Alloy 690 was conducted by heat treatments and subsequent microscopic examinations. Carbon had a strong influence on the grain growth behavior of this alloy. The grain boundaries were serrated in a limited temperature range during a controlled cooling. As the average grain size with more carbon content increased and/or the cooling rate decreased, the degree of serration increased with a precipitation of coarse intergranular Cr carbides. Cr carbides in Alloy 690 were identified as Cr23C6, and they grew in a planar shape along the curved grain boundaries. The grain boundaries had a convex shape into the incoherent grain, from which it is believed that the grain boundary shape is closely correlated with the grain boundary migration in this alloy during serration. (Received December 17, 2013)

저가 탄소섬유를 이용한 악취제거 기술 개발

임연수,유기상,김희석,정윤중,Lim, Yun-Soo,Yoo, Ki-Sang,Kim, Hee-Seok,Chung, Yun-Joong 한국세라믹학회 2001 한국세라믹학회지 Vol.38 No.10

In this study, two kinds of activated carbon fibers were prepared from PAN-based stabilized fibers by physical activation with steam. The variations in specific surface area, amount of iodine adsorption and pore size distribution of the activated carbon fibers after the activation process were discussed. The activated carbon fibers were prepared by two different methods, namely a 1- and 2-step method. For the 2-step method, carbonization of fibers in $N_2$ atmosphere was carried out to make carbon fibers and then activated by steam. In normal two step steam activation, BET surface area of about $1019m^2/g$ was obtained in the study. In the 1-step steam activation process, the carbonization and activation were simultaneously carried out. In the one step steam activation, BET surface area of $1635m^2/g$ was obtained after heat-treatment at $990^{\circ}C$. However, nitrogen adsorption isotherms for oxidized PAN based activated carbon fibers that were prepared by both methods were type I in the Brunauer-Deming-Deming-Teller (BDDT) classification even though they have different BET surface areas, amounts of iodine adsorption and pore size distributions. 본 연구에서는 PAN계 안정화섬유를 원료로 하여 수증기를 이용한 물리적 활성화에 의해 여러 등급의 활성탄소섬유를 제조하고, 비표면적, 요오드 흡착량, 미세구조, 세공구조 등을 측정하여 제조조건에 따른 그 특성변화를 고찰하였다. 수증기를 이용한 물리적 활성화에서 기존의 탄화과정과 활성화과정의 2단계를 이용한 공정과, 탄화공정과 활성화 공정을 동시에 수행하는 1단계 활성화과정을 비교함으로써 저가로 활성탄소섬유를 제조할 수 있는 제조방법을 연구하였다. 2단계 법에서는 안정화 섬유를 $900^{\circ}C$에서 탄화한 후 이를 다시 $900^{\circ}C$에서 활성화하는 방법으로 $1019m^2/g$의 비표면적을 갖는 활성탄소섬유를 얻었으나 1단계 방법에서는 $900^{\circ}C$에서 $1636m^2/g$의 비표면적을 갖는 활성탄소섬유를 제조하였다. 이들 활성탄소섬유 사이에는 비표면적, 요오드 흡착력, 기공분포 등이 서로 차이가 있음에도 불구하고, Brunauer-Deming-Deming-Teller(BDDT)에 의한 분류에서는 제I형을 나타내는 공통점도 가지고 있었다.

하수관용 HDPE배관 내 결함 탐상을 위한 초음파 특성 분석 연구

임연수(Yeon Soo Lim),염윤택(Yun Taek Yeom),김학준(Hak Joon Kim),송성진(Sung Jin Song),권성덕(Sung Duk Kwon),강성식(Sung Sik Kang) 대한기계학회 2017 대한기계학회 춘추학술대회 Vol.2017 No.11

A land depression in urban problem is occured in the world. It causes a huge economic and human damage. it is mostly caused by a leakage of sewer pipe. Today, sewer pipe inspections are conducted in visual inspection by human or robots. In that case, visual inspection can not detect cracks in water. To detect cracks completely, a visual inspection should be replaced by other nondestructive inspections. In this study, we tried to find defects in a sewer HDPE pipe by using ultrasound inspection. we made a artificial defect pipe specimen and fabricated scanner system which use a pulse-echo method. We checked each crack ultrasonic signal of cracks. As a result, There are differences in each crack signal because of sewer HDPE pipe shape so each crack signals could be distinguished by each wave characteristics.

한우 종모우의 지방괴사증에 대한 Isoprothiolane 투여효과

이성수,임연수,정준,장윤호,박종관,박노형,원유석,김상근,Lee, Seoung-soo,Lim, Yeoun-su,Jeong, Joon,Jang, Yun-ho,Park, Jong-kwan,Park, No-hyoung,Won, You-seog,Kim, Sang-keun 대한수의학회 1999 大韓獸醫學會誌 Vol.39 No.3

The effect of isoprothiolane(di-isopropyl-1,3-dithiolan-2-ylidenemalonate) aganist fat necrosis in Hanwoo(Korean Cattle) sire was evaluated. The 10 heads of Hanwoo sire suffering from fat necrosis were given 50mg/kg body weight of isoprothiolane(0.2g/kg of Fujix, Japan) orally once a day for 8 weeks. In 30% of these, the size of the necrotic fat masses had decreased significantly 7 months after the adminstration. Isoprothiolane did not affect on live body weight and semen characteristics. However the sire affected with fat necrosis had higher MCHC(Mean corpuscular hemoglobin concentration) than normal sire in hematologic values 10 weeks after administration. Number of RBC(red blood cell) and PCV(packed cell volume) 10 weeks after administration had been increased than those before administration(p < 0.05). The serum concentrations of creatinine, triglyceride, and total cholesterol 10 weeks after administration were higher than those before administration while the concentration of glucose was vice versa. The isoprothiolane may reduce the oxidation of glucose, increase the glucose transfer to lipids, and increase blood supply to necrotic masses. These results indicate that isoprothiolane may be useful as the therapeutic agent aganist fat necrosis.

수열합성법을 이용하여 우선 배향된 ZnO 나노와이어 성장 및 발광 특성

김종현,임연수,김성현,조진우,정대용,Kim, Jong-Hyun,Lim, Yun-Soo,Kim, Sung-Hyun,Jo, Jin-Woo,Jeong, Dae-Yong 한국재료학회 2011 한국재료학회지 Vol.21 No.12

1-D ZnO nanowires have been attractive for their peculiar properties and easy growth at relatively low temperature. The length, diameter, and density of ZnO nanowires were determined by the several synthetic parameters, such as PEI concentration, growth time, temperature, and zinc salt concentration. The ZnO nanowires were grown on the <001> oriented seed layer using the hydrothermal process with zinc nitrate and HMTA (hexamethylenetetramine) and their structure and optical properties were characterized. The morphology, length and diameter of the nanowires were strongly affected by the relative and/or absolute concentration of $Zn^{2+}$ and $OH^{-1}$ and the hydrothermal temperature. When the concentrations of the zinc nitrate HMTA were the same as 0.015 M, the length and diameter of the nanowires were $1.97{\mu}m$ and $0.07{\mu}m$, respectively, and the aspect ratio was 28.1 with the preferred orientation along the <001> direction. XRD and TEM results showed a high crystallinity of the ZnO nanowires. Optical measurement revealed that ZnO nanowires emitted intensive stimulated UV at 376 nm without showing visible emission related to oxygen defects.

고출력 리튬이온 이차전지 음극재용 피치/코크스/천연흑연 복합재의 제조 및 전기화학적 특성평가

고효준,임연수,김명수,Ko, Hyo Joon,Lim, Yun-Soo,Kim, Myung-Soo 한국재료학회 2015 한국재료학회지 Vol.25 No.6

In order to prepare anode materials for high power lithium ion secondary batteries, carbon composites were fabricated with a mixture of petroleum pitch and coke (PC) and a mixture of petroleum pitch, coke, and natural graphite (PC-NG). Although natural graphite has a good reversible capacity, it has disadvaantages of a sharp decrease in capacity during high rate charging and potential plateaus. This may cause difficulties in perceiving the capacity variations as a function of electrical potential. The coke anodes have advantages without potential plateaus and a high rate capability, but they have a low reversible capacity. With PC anode composites, the petroleum pitch/cokes mixture at 1:4 with heat treatment at $1000^{\circ}C$ (PC14-1000C) showed relatively high electrochemical properties. With PC-NG anode composites, the proper graphite contents were determined at 10~30 wt.%. The composites with a given content of natural graphite and remaining content of various petroleum pitch/cokes mixtures at 1:4~4:1 mass ratios were heated at $800{\sim}1200^{\circ}C$. By increasing the content of petroleum pitch, reversible capacity increased, but a high rate capability decreased. For a given composition of carbonaceous composite, the discharge rate capability improved but the reversible capacity decreased with an increase in heat treatment temperature. The carbonaceous composites fabricated with a mixture of 30 wt.% natural graphite and 70 wt.% petroleum pitch/cokes mixture at 1:4 mass ratio and heat treated at $1000^{\circ}C$ showed relatively high electrochemical properties, of which the reversible capacity, initial efficiency, discharge rate capability (retention of discharge capacity in 10 C/0.2 C), and charge capacity at 5 C were 330 mAh/g, 79 %, 80 %, and 60 mAh/g, respectively.

고분자 첨가에 의한 콜타르 핏치의 결정성 및 탄소섬유 물성 변화

김정담,윤재민,임연수,김명수,Kim, Jung-Dam,Yun, Jae-Min,Lim, Yun-Soo,Kim, Myung-Soo 한국재료학회 2016 한국재료학회지 Vol.26 No.4

In order to use coal tar pitch (CTP) as a raw material for carbon fibers, it should have suitable properties such as a narrow range of softening point, suitable viscosity and uniform optical properties. In this study, raw CTP was modified by heat treatment with three types of polymer additives (PS, PET, and PVC) to make a spinnable pitch for carbon fibers. The yield, softening point, C/H ratio, insoluble yield, and meso-phase content of various modified CTPs with polymer additives were analyzed by changing the type of polymer additive and the heat treatment temperature. The purpose of this study was to compare the properties of CTPs modified by polymer addition with those of a commercial CTP. After the pitch spinning, the obtained green fibers were stabilized and carbonized. The properties of the respective fibers were analyzed to compare their uniformity, diameter change, and mechanical properties. Among three polymer additives, PS220 and PET261 pitches were found to be spinnable, but the carbon fibers from PET261 showed mechanical properties comparable with those of a commercial CTP produced by an air-blowing method (OCI284). The CTPs modified with polymer additive had higher ${\beta}$-resin fractions than the CTP with only thermal treatment indicating a beneficial effect of carbon fiber application.