Quantitative Imaging with Low-dose CT in the PET/CT System

Sora Nam,김희중,유아람,최효민,이창래,박혜석 한국물리학회 2009 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.55 No.4

The use of Positron Emission Tomography/Computed Tomography (PET/CT) systems in clinical applications has rapidly increased. Not only has their diagnostic value increased due to their superior statistical noise characteristics but also compared to a single-modality PET system, they have shortened the acquisition time for the attenuation correction. Most commercially available PET/CT systems use the CT scan for the attenuation correction instead of the transmission scan, which uses a radioactive source, such as 137Cs or 67Ge. The effective dose of the CT attenuation correction, however, is up to 118 times larger than that of the radioactive isotope attenuation correction. As such, an increased dose is expected during the CT scan. The purpose of this study is to evaluate the quality of PET images that have been reconstructed using a CT attenuation map at various CT tube currents. Image data were obtained, using a 3-D Hoffman brain phantom and a cylindrical phantom, for both the GE DSTe PET/CT and the Philips GEMINI PET/CT systems. The CT data that were used to create an attenuation map were acquired at various tube currents and at doses from a diagnostic dose to an ultra-low dose. The CT image quality was evaluated by measuring the standard deviation (SD) of the cylindrical phantom filled with water. The PET image quality was evaluated by computing the activity ratio of the gray and the white matter in the 3-D Hoffman brain phantom images. In addition, the coefficient of variance (COV) was calculated to evaluate the CT and the PET images. The SDs of the CT data and the COVs of the CT images decreased when the tube current was increased. The activity ratios of the gray and the white matter with a ventricle area in the PET images remained almost constant for the CT attenuation maps at various tube currents. The DSTe and GEMINI systems’ activity ratios were approximately 3.76 ± 0.03 and 3.86 ± 0.03, respectively. The COVs of the PET images were almost the same in spite of the fact that the PET images’ attenuations were corrected by using different CT data. The results indicated that the quality of the PET images whose attenuations were corrected using low-dose CT was comparable to that of the PET images whose attenuations were corrected using diagnostic-dose CT. In conclusion, if the CT exam does not require a high-quality diagnostic CT, the use of low-dose CT rather than diagnostic-dose CT is recommended. The use of Positron Emission Tomography/Computed Tomography (PET/CT) systems in clinical applications has rapidly increased. Not only has their diagnostic value increased due to their superior statistical noise characteristics but also compared to a single-modality PET system, they have shortened the acquisition time for the attenuation correction. Most commercially available PET/CT systems use the CT scan for the attenuation correction instead of the transmission scan, which uses a radioactive source, such as 137Cs or 67Ge. The effective dose of the CT attenuation correction, however, is up to 118 times larger than that of the radioactive isotope attenuation correction. As such, an increased dose is expected during the CT scan. The purpose of this study is to evaluate the quality of PET images that have been reconstructed using a CT attenuation map at various CT tube currents. Image data were obtained, using a 3-D Hoffman brain phantom and a cylindrical phantom, for both the GE DSTe PET/CT and the Philips GEMINI PET/CT systems. The CT data that were used to create an attenuation map were acquired at various tube currents and at doses from a diagnostic dose to an ultra-low dose. The CT image quality was evaluated by measuring the standard deviation (SD) of the cylindrical phantom filled with water. The PET image quality was evaluated by computing the activity ratio of the gray and the white matter in the 3-D Hoffman brain phantom images. In addition, the coefficient of variance (COV) was calculated to evaluate the CT and the PET images. The SDs of the CT data and the COVs of the CT images decreased when the tube current was increased. The activity ratios of the gray and the white matter with a ventricle area in the PET images remained almost constant for the CT attenuation maps at various tube currents. The DSTe and GEMINI systems’ activity ratios were approximately 3.76 ± 0.03 and 3.86 ± 0.03, respectively. The COVs of the PET images were almost the same in spite of the fact that the PET images’ attenuations were corrected by using different CT data. The results indicated that the quality of the PET images whose attenuations were corrected using low-dose CT was comparable to that of the PET images whose attenuations were corrected using diagnostic-dose CT. In conclusion, if the CT exam does not require a high-quality diagnostic CT, the use of low-dose CT rather than diagnostic-dose CT is recommended.

조선후기 찬합의 제작과 사용양상

남소라(Nam, Sora) 한국미술사학회 2021 美術史學硏究 Vol.310 No.310

Organizational-Level Moderators on the SME Employees’ Adoption of Abandonment Option to Manage the Cloud Computing Service Risks

Sora Kang(강소라),Seung-Hyeon Nam(남승현),Hee-Dong Yang(양희동) 한국산업정보학회 2017 한국산업정보학회논문지 Vol.22 No.1

본 연구에서는 클라우드 서비스의 높은 실패율에 대하여, 어떠한 위험이 존재하는지 살펴보고, 이러한 위험을 제거하기 위한 실물 옵션, 특히 포기 옵션의 채택에 영향을 끼칠 수 있는 위험의 종류에 대하여 실증 분석을 실시하였다. 특히, 개인 차원에서 인식하는 위험의 정도가 포기 옵션의 채택에 어떠한 영향을 끼치는 지에 더하여, 조직 차원의 변수(CEO의 혁신성, 밴드웨건 효과)가 개인 차원의 효과들을 어떻게 조절하는지에 대하여 실증 분석을 실시한다. 수도권 소재 중소기업의 IT 담당자들을 대상으로 설문 조사한 내용을 바탕으로, 기술적 위험과 경제적 위험이 포기 옵션의 채택에 유의한 영향을 끼치며, CEO의 혁신성이 기술적 위험의 효과를 억제하는 조절 효과가 검증되었다. 그러나, 밴드웨건 효과는 개인 차원의 영향을 억제하는 조절 효과는 실증적으로 유의하지 않았다. In this Paper, We Empirically Investigated what kind of Risks Exist that Drive high Failure rate of cloud Services, and whether Perception of such risks leads to the Adoption of the Abandonment Option of cloud Services. Such risk Perception is the Individual-level Factor, and we Empirically Tested whether Organizational Contexts such as CEO`s Innovativeness and Dandwagon Effect can Moderate the Positive Effects of such Individual-level Risk Perception on the Adoption of Abandonment option. We Collected Survey data from IT Professionals Working for the Small and Medium-sized Companies near Seoul and found that the Perceived Technical Risk and Economic Risk Influence the Adoption of Abandonment Option. Out of two Organizational Contexts, only CEO`s Innovativeness Moderates the Positive Influence of Technical Risk on the Adoption of Abandonment Option. Organizational Factors Demonstrated very Limited Moderation Effect on the Influence of Individual-level Perception of Cloud Service Risk on the Adoption of Abandonment Option.

F1 in Schools 프로그램을 이용한 초등학생 대상 공학 기술 교육에 관한 연구

박소라(Sora Park),남현욱(HyunWook Nam) 한국공학교육학회 2008 공학교육연구 Vol.11 No.1

이 연구의 목적은 초등학교 학생들을 대상으로 한 ‘F1 in Schools Program’을 개발하여 적용하여 보고 학생, 학부모, 학교의 반응을 조사하여 현장 적용가능성을 평가하고자 하는데 있다. 충청북도 청주시 소재의 W 초등학교 5학년 15명의 어린이를 대상으로 ‘F1 in Schools Program’(초등학교 학생용 워크 북)을 개발한 후 현장 적용 가능성을 평가하기 위해 2007년 1월 22일부터 2월 2일까지 총 60차시에 걸쳐 수업을 진행하고 학생, 학부모, 학교의 반응을 조사하였다. 본 프로그램에서 활용하고 있는 CAD(Computer Aided Design), CFD(Computation Fluid Dynamics), CAM(Computer Aided Manufacturing), CNC Machine의 프로그램은 학생들이 직접 해볼 수 있는 참여와 신기성과 같은 특성으로 흥미를 끌기에 좋은 소재가 되고 있으나 프로그램을 조작하기에 초등학 생의 인지 발달 수준 및 공작 능력이 미치지 못하는 것으로 나타났다. 학생, 학부모, 학교의 프로그램에 대한 만족도는 비교적 높았으나 학생의 경우 시간이 부족하다 응답하였고, 학부모와 학교의 경우 프로그 램에 대한 이해가 부족함을 알 수 있었다. 학생들은 프로그램 실시 전보다 실시 후에 자동차의 속력과 관계된 과학적 개념이 향상되는 결과를 얻었다. The purpose of this study is development of ‘F1 in Schools Program’ for elementary school student and validation of the program. Fifteen students were originally chosen from the W elementary school in Cheongju, Chungcheogbuk-Do. The children were tested on their understanding of science and ‘F1 in Schools Program’. After developing the ‘F1 in Schools Program’, it was used in the classroom to evaluate applicability and to examine the responses from students, parents and schools. The program consists of 60 classes and the time of each class is 40 minutes. This study was conducted for 10 days from January 22nd, 2007 to February 2nd, 2007. CAD(Computer Aided Design), CFD(Computation Fluid Dynamics), CAM(Computer Aided manufacturing) and CNC Machine were used in this study and proved to be good materials for students in that they increased the students’ participation and imagination. However, the children’s cognitive and creative abilities as well as manuals written in English hampered the process. Most students, parents, schools seemed to be satisfied with use of the program. However, the schools showed that there was not enough understanding of the program as a whole. The processes with which students build and inspect using the CO₂Model Car not only improves the processing of the model but also enhanced the students scientific understanding related to the car speed.

Korean Version of the Longer-Term Unmet Needs After Stroke Questionnaire

Baek Sora,Kim Won-Seok,Park Yul-Hyun,Jung Yun Sun,Chang Won Kee,Kim Gowun,Paik Nam-Jong 대한재활의학회 2023 Annals of Rehabilitation Medicine Vol.47 No.5

Objective: To translate the 22-item Longer-term Unmet Needs after Stroke (LUNS) questionnaire, validate it in the Korean stroke population, and assess the reliability of face-to-face and telephone surveys.Methods: Sixty-six adult patients with stroke from Seoul National University Bundang Hospital and Kangwon National University Hospital were involved in the validation. Participants were interviewed twice using the LUNS Korean version: first, a face-to-face survey for validation, and second, a telephone survey for test-retest reliability. Participants completed the Frenchay Activities Index (FAI) and Short Form 12 (SF-12) Mental and Physical Component Summary (MCS and PCS) scores at the first interview. For concurrent validity, the differences in health status (FAI, SF-12 MCS and PCS) between the groups that reported unmet needs and those that did not were analyzed for each item. Cohen’s kappa and percentage of agreement between the first and second administrations were calculated for each item to determine the test-retest reliability.Results: The average age of the participants was 61.2±12.8 years and 74.2% were male. Fifty-seven patients were involved in the second interview. Depending on the unmet needs, SF-12 MCS, PCS, and FAI were significantly different in 12 of 22 items. In the test-retest reliability test, 12 items had a kappa of 0.6 or higher, and two had a kappa of <0.4.Conclusion: The LUNS instrument into Korean (LUNS-K) is a reliable and valid instrument for assessing unmet health needs in patients with stroke. In addition, telephone surveys can be considered reliable.

Efficient pathway enrichment and network analysis of GWAS summary data using GSA-SNP2

Yoon, Sora,Nguyen, Hai ,C ,T,Yoo, Yun J,Kim, Jinhwan,Baik, Bukyung,Kim, Sounkou,Kim, Jin,Kim, Sangsoo,Nam, Dougu Oxford University Press 2018 Nucleic acids research Vol.46 No.10

<P><B>Abstract</B></P><P>Pathway-based analysis in genome-wide association study (GWAS) is being widely used to uncover novel multi-genic functional associations. Many of these pathway-based methods have been used to test the enrichment of the associated genes in the pathways, but exhibited low powers and were highly affected by free parameters. We present the novel method and software GSA-SNP2 for pathway enrichment analysis of GWAS <I>P</I>-value data. GSA-SNP2 provides high power, decent type I error control and fast computation by incorporating the random set model and SNP-count adjusted gene score. In a comparative study using simulated and real GWAS data, GSA-SNP2 exhibited high power and best prioritized gold standard positive pathways compared with six existing enrichment-based methods and two self-contained methods (alternative pathway analysis approach). Based on these results, the difference between pathway analysis approaches was investigated and the effects of the gene correlation structures on the pathway enrichment analysis were also discussed. In addition, GSA-SNP2 is able to visualize protein interaction networks within and across the significant pathways so that the user can prioritize the core subnetworks for further studies. GSA-SNP2 is freely available at https://sourceforge.net/projects/gsasnp2.</P>

화장품용 유화 제조기술 최근동향

황소라(Sora Hwang),남진오(Jin-Oh Nam),이병진(Byung-Jin Lee),송우호(Woo-Ho Song),이창수(Chang-Soo Lee) 한국생물공학회 2012 KSBB Journal Vol.27 No.4

Emulsions are mixture of immiscible liquids in which one is dispersed in all over the other. They have been applied to many applications including cosmetics, foods, drug delivery system (DDS), fine chemicals, and chemical separations. Especially, emulsion technology is one of the most useful technique to formulate cosmetics such as eye cream, foundation, and foam cleansing. In general, the emulsions can be generated by mechanical agitation of two immiscible fluids. However, the emulsions obtained by conventional method have limited in stability, monodispersity, and complicate process. We describe here preparation techniques of representative cosmetic emulsions such as liposome, liquid crystal emulsion, nanoemulsion, multiple emulsion, and pickering emulsion. Furthermore, various factors which can control the physical properties of each cosmetic emulsions are briefly discussed.

A Fully Closed Nano-Focus X-Ray Source With Carbon Nanotube Field Emitters

Park, Sora,Kang, Jun-Tae,Jeong, Jin-Woo,Kim, Jae-Woo,Yun, Ki Nam,Jeon, Hyojin,Go, Eunsol,Lee, Jeong-Woong,Ahn, Yujung,Yeon, Ji-Hwan,Kim, Sunghee,Song, Yoon-Ho IEEE 2018 IEEE electron device letters Vol.39 No.12

<P>We developed a fully closed nano-focus X-ray source using carbon nanotube (CNT) field emitters. The nano-focus X-ray source includes a fully vacuum-sealed CNT Electron-gun (E-gun) tube and E-beam-focusing modules consisting of electrostatic and magnetic lenses, facilitating very compact and high-resolution X-ray imaging. The paste-printed CNT emitters were prepared in a small pattern as an electron source, and the entire components, including the CNT emitter module, Cu tubes, collimators, and transmissive anode target, were specially brazed at an elevated temperature, resulting in a very compact E-gun tube. The CNT emitter showed a stable and reliable emission current with its density of over 300 mA/cm<SUP>2</SUP> even in the vacuum-sealed E-gun tube. With the anode grounded and the CNT emitter module biased to negative high voltages, we achieved a considerably magnified x-ray image of a several hundred nanometer resolution. The fully vacuum-sealed CNT E-gun tube along with the magnetic lens module can offer much more compact, easily maintainable, high-resolution X-ray imaging compared with conventional open-type thermionic X-ray sources.</P>

Esophageal Motility Disorders in Patients With Esophageal Barium Residue After Videofluoroscopic Swallowing Study

Jintae Park,Sora Baek,Gowun Kim,Seung-Joo Nam,Ji Hyun Kim 대한재활의학회 2022 Annals of Rehabilitation Medicine Vol.46 No.5

Objective To investigate esophageal motility disorders in patients with esophageal residual barium on chest x-rays after videofluoroscopic swallowing studies (VFSS) through high-resolution esophageal manometry (HREM).Methods We reviewed the records of 432 patients who underwent VFSS from September 2019 to May 2021, and 85 patients (19.7%) with large residual barium (diameter ≥1 cm) were included. As a result of HREM, motility disorders were classified as major or minor motility disorders according. Esophagogastroduodenoscopy and chest computed tomography results available were also reviewed.Results Among 85 patients with large residual barium in the esophagus, 16 patients (18.8%) underwent HREM. Abnormal esophageal motilities were identified in 68.8% patient: three patients (18.8%) had major motility disorders—achalasia (n=1), esophagogastric junction (EGJ) outflow obstruction (n=2)—and eight patients (50%) had minor motility disorders—ineffective esophageal motility (n=7), fragmented peristalsis (n=1). In those with normal esophageal motility, three patients of esophageal structure disorders (18.8%)—esophageal cancer (n=1), cardiogenic dysphagia (n=1), slight narrowing without obstruction of EGJ (n=1)—and two patients (12.5%) with chronic atrophic gastritis (n=2) were confirmed.Conclusion Esophageal motility disorders were identified in 68.8% of 16 patients with large esophageal residual barium with three patients in the major and eight patients in the minor categories. Residual barium in the esophagus was not rare and can be a sign of significant esophageal motility disorders.

Demonstration of the Heterolytic OO Bond Cleavage of Putative Nonheme Iron(II)OOH(R) Complexes for Fenton and Enzymatic Reactions

Bang, Suhee,Park, Sora,Lee, Yong‐,Min,Hong, Seungwoo,Cho, Kyung‐,Bin,Nam, Wonwoo WILEY‐VCH Verlag 2014 Angewandte Chemie Vol.126 No.30

<P><B>Abstract</B></P><P>One‐electron reduction of mononuclear nonheme iron(III) hydroperoxo (Fe<SUP>III</SUP>OOH) and iron(III) alkylperoxo (Fe<SUP>III</SUP>OOR) complexes by ferrocene (Fc) derivatives resulted in the formation of the corresponding iron(IV) oxo complexes. The conversion rates were dependent on the concentration and oxidation potentials of the electron donors, thus indicating that the reduction of the iron(III) (hydro/alkyl)peroxo complexes to their one‐electron reduced iron(II) (hydro/alkyl)peroxo species is the rate‐determining step, followed by the heterolytic OO bond cleavage of the putative iron(II) (hydro/alkyl)peroxo species to give the iron(IV) oxo complexes. Product analysis supported the heterolytic OO bond‐cleavage mechanism. The present results provide the first example showing the one‐electron reduction of iron(III) (hydro/alkyl)peroxo complexes and the heterolytic OO bond cleavage of iron(II) (hydro/alkyl)peroxo species to form iron(IV) oxo intermediates which occur in nonheme iron enzymatic and Fenton reactions.</P>