구미산업단지 대기중 휘발성유기화합물(VOCs)의 농도특성

최우건,배상호,박덕신,정연구,김태오 한국환경과학회 2004 한국환경과학회지 Vol.13 No.3

This study focuses on the measurement of airborne Volatile Organic Compounds (VOCs) in the Kumi electronic industrial complex during the time periods of August and September, 2002 and January and February, 2003. This study was based on the US-EPA method TO-14 while the VOCs were analyzed with GC/MSD. The toluene level revealed high concentration at all measurement sites. The areal rank of average concentrations of VOCs is as follows : industry l>industry2>urban>middle>residential. Concentrations of VOCs in Kumi electronic industrial ones were generally higher than at Yeochon and Ulsan industrial complexes. Dichloromethane and trichloroethylene, which are used as a cleaner in the process of electronic industries, were observed 4 to 8 times higher than those of other areas. Among the aromatic compounds, toluene showed the highest level, while the concentrations of dichloromethane and trichloroethylene were higher than those of other halogen compounds. In Kumi, toluene, trichloroethylene, and dichloromethane were confirmed as the major compounds of VOCs by this research.

중성자에 조사된 원자로 압력용기 재료(SA508)의 Magneto-acoustic emission 효과

홍준화,박덕근,옥치일,김장환,이종규 韓國非破壞檢査學會 1999 한국비파괴검사학회지 Vol.19 No.6

원자로 압력용기 재료인 SA508 steel을 온도 70 ℃와 대기압하에서 최고 10 n/㎠까지 중성자를 조사시켜 조사량에 따른 미세경도 변화와 magneto-acoustic emission(MAE) 에너지를 측정하였다. 중성자 조사에 따른 경도의 변화는 조사량이 10 /㎠까지는 거의 일정하였으나, 조사량이 10 /㎠이상에서 급격히 증가하였다. MAE 에너지의 변화는 중성자 조사량에 따라 경도의 변화와 같은 형태로 변하였으나 그 변화량은 감소하여 그변화의 추이는 경도의 변화와는 역의 형태였고, 또한 MAE에너지의 상대적 변화와 경도 변화사이에는 아주 좋은 선형성을 보였다. 이러한 결과에서 SA508 강재는 10 /㎠이상의 중성자에 조사될 경우에 재료에 중성자 조사에 의한 미세 결함이 급격히 증가하여 전위(dislocation)이동에 대한 저항성을 나타내는 마찰경화의 증가가 경도의 증가를 유발하고, 또한 이러한 미세 결함은 자기장과의 반응에서는 90°자벽의 운동중에 자기탄성 변화를 유도하여 MAE 에너지의 감소를 유발함을 알 수 있었다. 그리고 경도의 변화량보다 MAE 에너지의 변화량이 더 크게 나타나, 중성자 조사에 의한 미세결함은 기계적 성질보다 자기적 성질에 더 민감하게 반응한다는 것을 알 수 있었다.따라서 MAE가 중성자 조사에 의한 재료의 미세 구조 결함을 비파괴적인 방법으로 평가하는 강력한 도구의 가능성이 있음을 알 수 있었다. Magneto-acoustic emission (MAE) energy and hardness were measured in the reactor pressure vessel steel (SA508 Steel) for the various neutron fluence, irradiated dose up to 10 n/㎠. The hardness was nearly a constant up to 10 n/㎠, but it was rapidly increased with an increase of the neutron irradiation above 10 n/㎠. It may be considered that the increase of hardness is due to the hindrance of dislocation motion induced defect clusters by irradiation. On the other hand, the MAE energy was slowly decreased as the neutron irradiation increased up to 10 n/㎠ and it was rapidly decreased with an increase of the neutron irradiation increased up to 10 n/㎠ and it was rapidly decreased with an increase of the neutron irradiation above 10 n/㎠. The decrease of the MAE energy may be considered as an increase of the defect clusters which is very sensitive to the 90°domain wall motion. Furthermore, the change of MAe energy and hardness had nearly a linear relationship, but the change of MAE energy was more significant than the change of the hardness. Therefore, MAe may be considered as a very useful technique for the nondestructive evaluation of irradiation damage.

중성자에 조사된 원자로 압력용기 재료의 Barkhausen 노이즈에 관한 연구

옥치일,김장환,박덕근,홍준화,이종규 韓國非破壞檢査學會 1998 한국비파괴검사학회지 Vol.18 No.6

원자로 압력용기 재료인 SA508 steel을 온도 70℃와 대기압하에서 최고 10 n/㎠까지 중성자를 조사시켜 조사량에 따른 자기이력곡선과 Barkhausen noise amplitude(BNA), Barkhausen noise energy(BNE) 및 미세경도 변화를 측정하여 이들 사이의 상관관계를 구하였다. 중성자 조사에 의하여 자기이력곡선은 변화가 없었으며, BNA, BNE 및 경도는 중성자 조사량에 따라 세 단계의 변화를 보였으며, 중성자 조사량이 10 n/㎠에서는 급격히 변하여 이들 사이의 상관관계가 있음을 알 수 있었다. 따라서 BNA와 BNE가 중성자 조사에 의한 재료의 미세 구조 결함을 조사하는데 비파괴적인 방법으로 가능성이 있음을 알 수 있었다. Hysteresis loop, Barkhausen noise(BN), and hardness were measured in the neutron irradiated RPV steel for various fluence, irradiated dose up to 10 n/㎠. The coercivity, remanence and maximum induction of neutron irradiated samples did not change significantly, but the BNA and BNE were decreased as the neutron irradiation increased. The changes of BNE and BNA were characterized by three stages with respect to neutron dose. The BNA and BNE were decreased with an increase of neutron dose to 10 n/㎠, and remained nearly constant up to 10 n/㎠, then were decreased rapidly with an increase of the neutron dose above 10 n/㎠. On the other hand, the hardness was observed revesely with the change of BNA and BNE.

원자로압력용기장 용접열영향부의 미세조직 변화가 Magnetic Barkhausen Noise 거동에 미치는 영향

김주학,윤의박,문종걸,박덕근,홍준화 韓國非破壞檢査學會 1998 한국비파괴검사학회지 Vol.18 No.4

최근 자기적 특성의 변화가 재료의 미세조직적 상태에 민감하다는 보고가 있다. 재료의 미세조직은 상(phase), 결정립의 크기, 석출물 등의 다양한 인자로 구성되며, 본 연구에서는 이러한 인자들을 이용하여 재료의 특성과 Barkhausen noise(BN)의 관계를 연관시키기 위한 시도를 하였다. ASTM A 508 Gr.3 원자로압력용기강을 대상으로 용접열영향부의 미세조직적인 변화를 일곱가지 대표적인 영역으로 구분하였고, 각 영역에서의 미세조직과 기계적특성의 변화를 파악한 후, 각 조건별로 BN을 측정하였다. 통상의 보자력이나 잔류자화 같은 자기적 성질은 큰 변화가 없었지만, BN은 미세조직의 상태에 따라 현격한 변화를 보였다. 결정립과 석출물의 크기가 증가함에 따라 BN은 증가하였고, tempered martensite 보다는 tempered bainite 조직에서 높은 BN을 나타냈다. Recent study has demonstrated that some magnetic properties are sensitive to the microstructural state of material. The ASTM A 508 Gr. 3 reactor pressure vessel steel has various microstructural changes including martensitic and bainitic phases, and various sizes of grain and precipitates in the weld heat-affected zone (HAZ). To correlate the microstructural state with Barkhausen noise (BN), specimens were prepared through simulating various weld thermal cycles using a thermal simulator. The conventional magnetic properties, i.e. coercive force, remanence and maximum induction, did not change significantly. whereas the BN amplitude and energy during a magnetization cycle changed markedly with microstructural state. The BN increased with increasing grain and carbide sizes, and the tempered bainite structure showed higher BN parameter than tempered martensite.

Effects of Magnetic Phase on the ECT Signal in the SG Tubes

Duck-Gun Park,Kwon Sang Ryu,Derac Son,Yong Moo Cheong IEEE 2010 IEEE transactions on magnetics Vol.46 No.2

<P>The magnetic phase created in the Inconel alloy which is called permeability variation cluster (PVC) results in the distortion of an eddy current test (ECT) signal during the inspection of steam generator (SG) of a nuclear power plant (NPP). The effects of magnetic phase on ECT signals were analyzed using the inspection data of NPP. The hysteresis loops were measured for the PVC which is extracted from retired SG tubes of Kori-1 NPP. The tensile tests were performed to identify the mechanism of PVC creation. The coercivity of PVC is larger than 200 Oe, and hysteresis loop appeared in the tensile tested specimen at 600°C.</P>

A study on the role of surface crystalline phase in amorphous ribbon using ferromagnetic resonance

Duck-Gun Park,Chul-Gi Kim,Sang-Chul Kwon,Jun-Hwa Hong 한국자기학회 2003 한국자기학회 학술연구발표회 논문개요집 Vol.13 No.2

Detection of gamma-irradiation effect on DNA and protein using magnetic sensor and cyclic voltammetry.

Park, Duck-Gun,Song, Hoon,Kishore, M B,V?rtesy, G,Lee, Duk-Hyun American Scientific Publishers 2013 Journal of Nanoscience and Nanotechnology Vol.13 No.11

<P>In this study, a magnetic sensor utilizing Planar Hall Resistance (PHR) and cyclic Voltammetry (CV) for detecting the radiation effect was fabricated. Specifically, we applied in parallel a PHR sensor and CV device to monitor the irradiation effect on DNA and protein respectively. Through parallel measurements, we demonstrated that the PHR sensor and CV are sensitive enough to measure irradiation effect. The PHR voltage decreased by magnetic nanobead labeled DNA was slightly recovered after gamma ray irradiation. The behavior of cdk inhibitor protein p21 having a sandwich structure of Au/protein G/Ab/Ag/Ab was checked by monitoring the cyclic Voltammetry signal in analyzing the gamma ray irradiation effect.</P>

The Magnetic and Structural Change of <tex> ${\hbox{Fe}}_{3}{\hbox{Ni}}$</tex> Alloy Due to Thermal Annealing

Duck-Gun Park,Kim, S. S.,Kim, Y. S.,Son, D.,Yong Moo Cheong IEEE 2011 IEEE transactions on magnetics Vol.47 No.10

<P>In this investigation, the changes of magnetic properties with thermal ageing of Fe<SUB>3</SUB>Ni alloy have been measured. The changes in coercivity and Barkhausen noise were measured, and the results have been interpreted as magnetic ordering, based on the neuron diffraction results. The Fe<SUB>3</SUB>Ni alloy forms ordered superstructures, and the investigation gives the information concerning the effect of atomic ordering on the magnetic structure. The neutron diffraction results shows that the superlattice peaks correspond to a simple cubic lattice, and the intensity increases with increasing ageing time. In the ordered state, the intensity of super lattice shows inverse trends with (1 1 1) fcc peak, which means that disordered states transformed to ordered states with thermal ageing.</P>

Detection of the Subsurface Cracks in a Stainless Steel Plate Using Pulsed Eddy Current

Park, Duck-Gun,Angani, C. Sekar,Rao, B. P. C.,Vé,rtesy, Gabor,Lee, Duk-Hyun,Kim, Kyung-Ho Springer-Verlag 2013 Journal of nondestructive evaluation Vol.32 No.4

The Effects of Nano-Sized Defects on the Magnetic Properties in Thermal Aged Fe–Cu Alloys

Duck-Gun Park,Kishore, M. B.,Kyung-Ho Kim,Lee, N. H.,Lee, D. H.,Kobayashi, Satoru,Son, Derac IEEE 2014 IEEE transactions on magnetics Vol.50 No.11

<P>We evaluated the changes in magnetic properties due to cold rolling and thermal aging of a Fe-1%Cu model alloy in this paper. First, the alloy was 10% cold rolled, and isothermally aged at 753 K for 20, 200, and 1800 min. The hysteresis loops, magnetic Barkhausen noise, and Vickers micro hardness were measured, and the results are interpreted using the small angle neutron scattering measurement. The change of magnetic and mechanical properties can be interpreted in terms of the domain wall motion and dislocation dynamics associated with copper rich precipitates. The results were interpreted in terms of aging time dependence of the precipitates evolution, such as the volume fraction and size distribution.</P>