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NiCuZn계 페라이트의 소결온도 변화에 따른 전자파 흡수특성
박찬규,이상록 東亞大學校 2003 東亞論叢 Vol.40 No.-
A EMI/EMC preventing NiCuZn ferrite is prepared by sintering ferrite type or mixing ferrite powder with resin polymers. This paper describes the research on electromagnetic wave absorbtion and shielding properties by sintering temperature of NiCuZn ferrite. NiCuZn ferrite was made that calcination condition was 900℃ in air atmosphere and powder metallurgy process. The best sintering condition was 1080℃ in air atmosphere sinterability at sinterability thickness of 5mm.
NiCuZn계 페라이트의 화학적 조성변화에 따른 전자파 흡수특성
박찬규,이상록 東亞大學校 2003 東亞論叢 Vol.40 No.-
As the information communication technique was advanced, the damage of the electromagnetic waves is increasing. This study describes electromagnetic wave absorption properties according to chemical composition ratio of NiCuZn ferrite, which is used electromagnetic wave absorption and shielding material. The best composition ratio, as best condition of electromagnetic wave absorption properties, was Fe₂0₃ 49.0 mol%, NiO 8.5 mol%, CuO 8.5 mol%, ZnO 34.0 mol%.
김찬규,신영록,김현정,배상병,이남수,이규택,박성규,원종호,홍대식,박희숙 순천향대학교 2006 Journal of Soonchunhyang Medical Science Vol.12 No.1
Purpose: The gastrointestinal (GI) tract is the most common site of extranodal non-Hodgkin's lymphoma (NHL), which is increasing in incidence, but there is no established optimal treatment modality. Thus, this study was investigated the clinicohistologic feature, the therapeutic modalities, and the prognosis for GI-NHL, as well as the factors affecting it. Methods: We retrospectively analyzed 45 patients who had been diagnosed as having GI-NHL and had been followed up from July 1994 to February 2005 at Soonchunhyang University Hospital. The patients were divided into groups according to the site of origin and to various other features, and the survivals of the various groups were compared. The modified Ann Arbor system and WHO classification were adopted for staging and histopathologic classification, respectively. Results: GI-NHL of the stomach, small bowel, ileocecal region, and colon occurred in 28 patients (62.2%), 5 patients (11.1%), 3 patients (6.7%), and 8 patients (17.8%), respectively, In one patient, the entire gastrointestinal tract was diffusely involved. The median age of patients was b5 years (25~78 years), and male-to-female ratio was 1:1.1. Fourteen patients were in stage Ⅰ, 24 in stage Ⅱ, 4 in stage Ⅲ, and 3 in stage Ⅳ. Surgical resection was performed in 19 patients, and combination chemotherapy was performed in 43 patients. Surgical resection only was performed in 4 patients, Chemotherapy only was performed in 26 patients. The expected overall 5 year survival of 45 patients was 39.6%, and there was a significant survival difference between the stages, but between sites of origin (p=0.842). The most important factors influencing the survival was the stage and other factors were not significant. Conclusion: The stomach was the most common site of GI-NHL. Most GI-NHL were localized Stage was the most important prognostic factor. However, Prospective randomized studies are needed to approve the therapeutic modality.
이상록,염치호,박찬규 동아대학교 공과대학부설 생산기술연구소 1997 生産技術硏究所硏究論文集 Vol.2 No.1
The method for determining the stability and multiplicity of steady states, and steady reaction region in phase plane for chain branching reaction model in perfectly mixed flow tank reactors is proposed. The results proposed are as follows : 1) stability and multiplicity of steady states exist 2 points (T_S1 : node, T_S2 : saddle) in T<T_1 range, and 2 points (T_S3 : focus, T_S4 : saddle) in T>T_2range on F(T)=0 curve. 2) steady reaction region containing the steady states can be constructed by the state varialbes of a reactor in phase plane. All trajectories of the representative points pass into the region at the boundary surface since the representative points in the region never drift out, it is safe to keep the reactor operation in the region.
Chan Rok Park 한국자기학회 2021 Journal of Magnetics Vol.26 No.3
Integrated positron emission tomography (PET)/magnetic resonance (MR) imaging is gradually being used to improve the rate of cancer lesion detection in the medical field. To enhance the quality of PET/MR images, attenuation correction (AC) techniques are used by applying MR pulse sequences of the controlled aliasing in parallel imaging results in higher acceleration (CAIPI; MR ACDixon-Caipi) and the generation autocalibrating partially parallel acquisition (GRAPPA; MR ACDixon-Grappa), based on the T1-weighted two-point Dixon pulse sequence. In addition, quality control using a Jaszczak phantom filled with water and radioisotopes is frequently performed when scanning the patient. When acquiring MR-based AC PET images in the phantom study, artifacts are caused by high permittivity in water, and there is a limitation in the acquisition of uniform image quality. Therefore, the purpose of this study was to compare the image quality using phantom fluids with lower permittivity than water (sodium chloride (NaCl) NaCl+nickel sulfate (NiSO₄)) according to MR ACDixon-Caipi and MR ACDixon-Grappa pulse sequences using various quantitative analysis parameters: percent of non-uniformity (PNU), percent contrast recovery (PCR), signal to noise ratio (SNR), and coefficient of variation (COV). The results indicated that the image quality with NaCl+NiSO₄ fluid based on the results was 1.2-, 1.6-, 1.4-, and 1.1 times superior to that of NaCl fluid, respectively. In conclusion, NaCl+NiSO₄ fluid is suitable as a phantom fluid material in PET/MR images.
Chan Rok Park,Youngjin Lee,Hyungjin Yang 한국자기학회 2018 Journal of Magnetics Vol.23 No.3
The present study aims to confirm the attenuation correction (AC) in positron emission tomography (PET) images using various magnetic resonance (MR) sequences with and without the MR breast radiofrequency(RF) coil, and thus to evaluate the attenuation effect of the MR breast RF coil. To that purpose, we reconstructed non-attenuated PET data using the MR ACDixon-CAIPI, MR ACUTE, and MR ACDixon-GRAPPA sequences. The results indicated that the signal loss of the PET image with the MR breast RF coil was the lowest when the MR ACDixon-GRAPPA sequence was applied. In conclusion, the MR ACDixon-GRAPPA sequence maintained PET image quality when using the MR breast RF coil during PET/MR scanning.
Park, Chan Rok,Kim, Kyuseok,Lee, Youngjin Elsevier 2019 OPTIK -STUTTGART- Vol.178 No.-
<P><B>Abstract</B></P> <P>To avoid artifacts and interpretation mistakes, improvements in the uniformity of magnetic resonance imaging (MRI) is very important. The aim of this study is to develop a bias field-based uniformity correction algorithm and to confirm the feasibility of its application with an integrated positron emission tomography (PET)/MRI system using standard MRI pulse sequences (T2-weighted, half-Fourier, single-shot turbo spin echo, T2-weighted turbo spin echo with fat suppression, and three-dimensional, volumetric, T1-weighted gradient recalled echo interpolated breath-hold examination using controlled aliasing in parallel imaging that results in increased acceleration). We used phantoms containing NaCl and NaCl + NiSO<SUB>4</SUB> solutions, and considered the percent image uniformity (PIU) as the evaluation parameter. The elicited PIU results using the correction algorithm were distinct for all sequences and phantoms. The results of this study suggested that the bias field-based algorithm allows uniformity improvements in MRI in terms of PIU.</P>
Evaluation of MR-based PET Images with a Homogeneous map by Using Integrated PET/MR
Chan Rok Park,Jung Soo Kim,Beomyeol Baek,Seong Ho Kim,Hyung Jin Yang 한국물리학회 2018 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.73 No.5
This study intends to obtain magnetic resonance (MR)-based positron emission tomography (PET) images with a relatively uniform map by using a National Electrical Manufacturers Asso- ciation (NEMA) International Electrotechnical Commission (IEC) body phantom and to evaluate the PET phantom images by applying various reconstruction parameters in accordance with the protocol of the NEMA. In order to obtain a uniform MR-based map, we set the initial voltage of the RF transmitter adjustment algorithm to 75 V, and we obtained the attenuation-corrected PET image by applying the two-point vibe Dixon MR sequence. The images reconstructed using the 3D ordered subset expectation maximization (OSEM) algorithm with the point spread function (PSF) showed the highest percentage of contrast recovery and the lowest percentage background variabil- ity compared to the other 3D reconstruction algorithms like the Filtered backprojection (FBP), 3D OSEM, and 3D OSEM with PSF algorithms. The 3D OSEM with PSF reconstruction algorithm is confirmed to be effective for maintaining the optimum image quality.