탄소 중간물질 그리드를 사용한 DR system에서의 moire artifact에 관한 연구

이성주 ( Sungju Lee ),조효성 ( Hyosung Cho ),최성일 ( Sungil Choi ),조희문 ( Heemoon Cho ),오지은 ( Jieun Oh ),이소영 ( Soyoung Lee ),박연옥 ( Yeonok Park ),이민식 ( Minsik Lee ) 한국방사선학회 2008 한국방사선학회 논문지 Vol.2 No.4

비산란 그리드는 X선 영상에서 산란방사선을 제거시키기 위해 사용되고, 그에 따라 X선 영상의 대조도를 향상 시킬 수 있다. 그러나 많은 경우 디지털 X선 영상에서는 그리드의 부적절한 샘플링으로 인해 moire artifact를 발생 시키게 된다. 본 논문에서는 그리드 주파수, pixel pitch, 각도와 moire artifact의 상관관계에 관하여 분석하고 실험으로 확인하였다. 실험을 위하여 4..0 - 8.5 까지의 6가지 탄소 그리드를 사용하여 139 μm x139 μm pixel size의 DDR system에서 실험을 하였다. 본 실험을 통하여 획득한 moire artifact의 frequency는 이론적 계산값과 거의 같았고, 특히 그리드와 detector array의 각도에 따라 moire frequency가 달라지는 것을 확인 할 수 있었다. 본 연구를 통한 moire artifact에 대한 이론과 data는 향후 DR system에서 moire artifact제거에 큰 도움을 주리라 생각한다. Antiscatter grids are widely used in radiography to remove scattered X-rays and thus improve the image contrast. However, the use of grids makes moire artifact in the digital image, and this can be a critical reason for a mistaken diagnosis. In this paper, we examined that moire artifacts are how to relate with grid frequency, pixel pitch and grid rotation angle. To experiment we prepared 6 grids having different line frequencies (4.0 to 8.5lines/mm) and tested with a DR imager having a 139 μm x 139 μm pixel size. In the result of this experiment, we could get data about moire artifact that could be make solution to remove the line artifact for the successful use of the grid in digital radiography. The acquired data and theory through this experiment, are expected to make contribution to the elimination of moire artifact in the DR system.

탄소 중간물질 그리드를 사용한 DR system에서의 moiré artifact에 관한 연구

이성주(Sungju Lee),조효성(Hyosung Cho),최성일(Sungil Choi),조희문(Heemoon Cho),오지은(Jieun Oh),이소영(Soyoung Lee),박연옥(Yeonok Park),이민식(Minsik Lee) 한국방사선학회 2008 한국방사선학회 논문지 Vol.2 No.4

비산란 그리드는 X선 영상에서 산란방사선을 제거시키기 위해 사용되고, 그에 따라 X선 영상의 대조도를 향상 시킬 수 있다. 그러나 많은 경우 디지털 X선 영상에서는 그리드의 부적절한 샘플링으로 인해 moiré artifact를 발생 시키게 된다. 본 논문에서는 그리드 주파수, pixel pitch, 각도와 moiré artifact의 상관관계에 관하여 분석하고 실험으로 확인하였다. 실험을 위하여 4..0 - 8.5 까지의 6가지 탄소 그리드를 사용하여 139 ㎛ × 139 ㎛ pixel size의 DDR system에서 실험을 하였다. 본 실험을 통하여 획득한 moiré artifact의 frequency는 이론적 계산값과 거의 같았고, 특히 그리드와 detector array의 각도에 따라 moiré frequency가 달라지는 것을 확인 할 수 있었다. 본 연구를 통한 moiré artifact에 대한 이론과 data는 향후 DR system에서 moiré artifact 제거에 큰 도움을 주리라 생각한다. Antiscatter grids are widely used in radiography to remove scattered X-rays and thus improve the image contrast. However, the use of grids makes moiré artifact in the digital image, and this can be a critical reason for a mistaken diagnosis. In this paper, we examined that moiré artifacts are how to relate with grid frequency, pixel pitch and grid rotation angle. To experiment we prepared 6 grids having different line frequencies (4.0 to 8.5lines/㎜) and tested with a DR imager having a 139 ㎛ × 139 ㎛ pixel size . In the result of this experiment, we could get data about moiré artifact that could be make solution to remove the line artifact for the successful use of the grid in digital radiography. The acquired data and theory through this experiment, are expected to make contribution to the elimination of moiré artifact in the DR system.

Earnings Management Behavior of Firms with Financial Constraints: Focusing on Firms that Issue Redeemable Convertible Preferred Stocks

Hyun-Ah Lee(Hyun-Ah Lee),Sungju Chun(Sungju Chun) People&Global Business Association 2023 Global Business and Finance Review Vol.28 No.1

Purpose: T his study aim s to e xplore t he e ffect of f inancial c onstraints o n earnings m anagement by f ocusing on firms that issue redeemable convertible preferred stocks (RCPS). RCPS are considered a financing option primarily used by firms that have investment opportunities but face difficulties in raising funds with a low cost of capital. Therefore, the issuance of RCPS can be an effective indicator to identify firms with financial constraints. Design/methodology/approach: This study employs a sample of 12,406 firm-year observations of listed companies in the Korean stock market from 2011 to 2018. The study conducts multiple regression analyses to investigate the level of earnings management of RCPS-issuing firms with respect to that of non-issuing firms. In this analysis, the earnings management is proxied by discretionary accruals and real operational activities. Findings: This study shows that RCPS-issuing firms have a higher level of discretionary accruals than non-issuing firms. Meanwhile, there is no significant difference in the level of real activities management between RCPS-issuing and non-issuing firms. These findings imply that firms with financial constraints engage in aggressive earnings management through discretionary accruals rather than real operational activities. Research limitations/implications: This study provides compelling evidence that financially constrained firms strategically use discretionary accruals to signal positive prospects for external capital suppliers, allowing them to raise the capital necessary for investment. It is also confirmed that financially constrained firms do not depend on real activities management, which sacrifices cash flows and firm value in the long run. Originality/value: T his is t he f irst s tudy t o test t he l ink between f inancial c onstraints a nd e arnings m anagement by analyzing RCPS-issuing firms that conform to the definition of financial constraints. This approach can alleviate the risk of errors in the classification of firms and the endogeneity problems accompanied by estimating financially constrained firms with firm characteristics, such as dividend payout ratio, cash flows, size, age, or a combined index of these variables.

Secure and Energy-Efficient Transmissions of Fingerprint Images

Sungju Lee,Seungwoo Hong,Hakjea Kim,Yongwha Chung,Sungbum Pan 대한전자공학회 2010 ICEIC:International Conference on Electronics, Inf Vol.1 No.1

In order to provide remote user authentication services with handheld devices equipped with fingerprint sensors, both energy efficiency and confidentiality/privacy requirements should be satisfied. However, nothing is known about the collective performance of fingerprint verification and secure transmission protocol in remote applications. In this paper, we consider the possible scenarios of an application to securely transmit fingerprint images from a handheld device to a server. It uses both encryption and watermarking and ensures efficiency using compression standards(i.e., WSQ and JPEG2000). Based on the evaluation, the compression scenario using WSQcan reduce the total energy consumption of the no-compression scenario by 33% without significant degradation of the fingerprint recognition rate or watermarking detection rate.

Phase I Trial of Anti-MET Monoclonal Antibody in MET-Overexpressed Refractory Cancer

Lee, Jeeyun,Kim, Seung Tae,Park, Sungju,Lee, Sujin,Park, Se Hoon,Park, Joon Oh,Lim, Ho Yeong,Ahn, Hongmo,Bok, Haesook,Kim, Kyoung-Mee,Ahn, Myung Ju,Kang, Won Ki,Park, Young Suk Elsevier 2018 Clinical colorectal cancer Vol.17 No.2

<P><B>Abstract</B></P> <P><B>Background</B></P> <P>Samsung Advance Institute of Technology-301 (SAIT301) is a human immunoglobulin G2 antibody that can specifically target mesenchymal epithelial transition factor (c-MET). This novel antibody has higher priority over hepatocyte growth factors when binding to the Sema domain of c-MET and accelerates the internalization and degradation of c-MET, proving its powerful antitumor activities in intra- as well as extracellular areas.</P> <P><B>Materials and Methods</B></P> <P>SAIT301 was administered intravenously once every 3 weeks in c-MET overexpressed solid tumor patients, focusing on metastatic colorectal cancer (CRC) according to common clinical phase I criteria. Dose escalation was performed according to a modified Fibonacci design, following the conventional 3+3 design. The purpose of this phase I study was to assess the safety profile, to establish the recommended dose for clinical phase II studies and to assess potential anticancer activity of the compound.</P> <P><B>Results</B></P> <P>Sixteen patients with a median age of 56 (range, 39-69) years were enrolled in the study. The most common adverse events were decreased appetite (50.0%), hypophosphatemia, fatigue and dizziness (25.0%, respectively), and diarrhea, blood alkaline phosphatase increased and dyspnea (18.8%, respectively). For tumor response, no patients achieved complete response. One (9.1%) CRC patient had a partial response in the 1.23 mg/kg group, 4 (36.4%) patients achieved stable disease (2 in the 0.41 mg/kg group, 2 in the 1.23 mg/kg group, 0 in the 3.69 mg/kg group, and 1 in the 8.61 mg/kg group). Because of the increase in dose-limiting toxicities (DLTs) at 8.61 mg/kg, the 3.69 mg/kg dose was considered the maximum tolerated dose and selected for further assessment in phase II.</P> <P><B>Conclusion</B></P> <P>We successfully completed a phase I trial with MET antibody in a MET-overexpressed patient population focusing on CRC, and found that the DLTs were alkaline phosphatase elevation or hypophosphatemia. The recommended dose of SAIT301 for phase II is the dose of 3.69 mg/kg.</P>

A Practical Implementation of Fuzzy Fingerprint Vault

( Sungju Lee ),( Yongwha Chung ),( Daesung Moon ),( Sung Bum Pan ),( Chang-ho Seo ) 한국인터넷정보학회 2011 KSII Transactions on Internet and Information Syst Vol.5 No.10

Recently, a cryptographic construct, called fuzzy vault, has been proposed for crypto-biometric systems, and some implementations for fingerprint have been reported to protect the stored fingerprint template by hiding the fingerprint features. In this paper, we implement the fuzzy fingerprint vault, combining fingerprint verification and fuzzy vault scheme to protect fingerprint templates. To implement the fuzzy fingerprint vault as a complete system, we have to consider several practical issues such as automatic fingerprint alignment, verification accuracy, execution time, error correcting code, etc. In addition, to protect the fuzzy fingerprint vault from the correlation attack, we propose an approach to insert chaffs in a structured way such that distinguishing the fingerprint minutiae and the chaff points obtained from two applications is computationally hard. Based on the experimental results, we confirm that the proposed approach provides higher security than inserting chaffs randomly without a significant degradation of the verification accuracy, and our implementation can be used for real applications.

Growth factor-expressing human neural progenitor cell grafts protect motor neurons but do not ameliorate motor performance and survival in ALS mice

Sungju Park,Hyoung-Tae Kim,윤석환,Il-Sun Kim,Jiyoon Lee,Il-Shin Lee,박국인 생화학분자생물학회 2009 Experimental and molecular medicine Vol.41 No.7

Neural progenitor cells (NPs) have shown several promising benefits for the treatment of neurological disorders. To evaluate the therapeutic potential of human neural progenitor cells (hNPs) in amyotrophic lateral sclerosis (ALS), we transplanted hNPs or growth factor (GF)-expressing hNPs into the central nervous system (CNS) of mutant Cu/Zn superoxide dismutase (SOD1G93A) transgenic mice. The hNPs were engineered to express brain-derived neurotrophic factor (BDNF), insulin-like growth factor-1 (IGF-1), VEGF, neurotrophin-3 (NT-3), or glial cell-derived neurotrophic factor (GDNF), respectively, by adenoviral vector and GDNF by lentiviral vector before transplantation. Donor-derived cells engrafted and migrated into the spinal cord or brain of ALS mice and differentiated into neurons, oligodendrocytes, or glutamate transporter-1 (GLT1)-expressing astrocytes while some cells retained immature markers. Transplantation of GDNF- or IGF-1-expressing hNPs attenuated the loss of motor neurons and induced trophic changes in motor neurons of the spinal cord. However, improvement in motor performance and extension of lifespan were not observed in all hNP transplantation groups compared to vehicle-injected controls. Moreover, the lifespan of GDNF-expressing hNP recipient mice by lentiviral vector was shortened compared to controls, which was largely due to the decreased survival times of female animals. These results imply that although implanted hNPs differentiate into GLT1-expressing astrocytes and secrete GFs, which maintain dying motor neurons, inadequate trophic support could be harmful and there is sexual dimorphism in response to GDNF delivery in ALS mice. Therefore, additional therapeutic approaches may be required for full functional recovery.

Energy-Efficient Biometrics-Based Remote User Authentication for Mobile Multimedia IoT Application

( Sungju Lee ),( Jaewon Sa ),( Hyeonjoong Cho ),( Daihee Park ) 한국인터넷정보학회 2017 KSII Transactions on Internet and Information Syst Vol.11 No.12

Recently, the biometric-based authentication systems such as FIDO (Fast Identity Online) are increased in mobile computing environments. The biometric-based authentication systems are performed on the mobile devices with the battery, the improving energy efficiency is important issue. In the case, the size of images (i.e., face, fingerprint, iris, and etc.) affects both recognition accuracy and energy consumption, and hence the tradeoff analysis between the both recognition accuracy and energy consumption is necessary. In this paper, we propose an energy-efficient way to authenticate based on biometric information with tradeoff analysis between the both recognition accuracy and energy consumption in multimedia IoT (Internet of Things) transmission environments. We select the facial information among biometric information, and especially consider the multicore-based mobile devices. Based on our experimental results, we prove that the proposed approach can enhance the energy efficiency of GABOR+LBP+GRAY VALUE, GABOR+LBP, GABOR, and LBP by factors of 6.8, 3.6, 3.6, and 2.4 over the baseline, respectively, while satisfying user's face recognition accuracy.

Applying Multi-modal and Correlation Analysis on Environmental Parameters and Effect on Cardiopulmonary Endurance of Gender in Elderly People

LEE, Sungju,REZAEI, Mehdi,JEONG, Taikyeong Tehran University of Medical Sciences 2018 Iranian journal of public health Vol.47 No.4

<P><B>Background:</B></P><P>The aim of this study was to investigate the correlation and interaction between the air pollution’s components with cardiopulmonary endurance of elderly people in eight regions by using a multi-modal and correlation analysis.</P><P><B>Methods:</B></P><P>The data of air pollution was collected in eight selected regions in 2013 to 2015. At the same time, total number of 880 male and female, older than 65 year-olds, were investigated based on the cardiopulmonary endurance measurement in the same regions. The correlation, interaction and multiple linear regressions was tested between the air pollution components in each region and cardiopulmonary endurance of elderly people, also between the air pollution components in each region and gender, respectively. In this case, the regression analysis for both hypotheses was conducted.</P><P><B>Results:</B></P><P>There was a correlation between the level of air pollution and cardiopulmonary endurance, especially for the carbon monoxide which has a strong effect, it was followed by the effect of sulfur dioxide and fine dust, meanwhile nitrogen dioxide seems not to be effective for this measurement test. Furthermore, it was highly unlikely that gender was a significant factor for the correlation between air pollution and cardiopulmonary endurance.</P><P><B>Conclusion:</B></P><P>The importance and correlation between air pollution and cardiopulmonary capacity is a critical determinant for the public health of a society, while at the same time having a serious impact on certain age groups. Provided that the factor of gender is highly unlikely to modify this impact, it is necessary to study the potential of other factors.</P>

Application of Pulsation Analysis for Reciprocal Pump Piping System of Offshore Production Plant

Sungju Lee(이성주),Yonghwan Park(박용환),Bongjae Kim(김봉재) 한국소음진동공학회 2016 한국소음진동공학회 학술대회논문집 Vol.2016 No.10