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Efficient Database Encryption Scheme for Database-as-a-Service Environment
Hankyu Joo 보안공학연구지원센터 2015 International Journal of Security and Its Applicat Vol.9 No.5
Computing-as-a-service is gaining ground. Clients may use the service without purchasing the system supporting the service. Database-as-a-Service (DBaaS) is an important area of computing-as-a-service. DBaaS allows clients to use an expensive database management system without purchasing it. In a DBaaS environment, database Tables are stored on servers belonging to a service provider, and hence, they must be encrypted in order to ensure data confidentiality. However, the encryption introduces performance degradation in the execution of queries over encrypted data. The execution of range queries, in particular, undergoes severe performance degradation. Several encryption schemes to alleviate this problem have been proposed. However, most of these schemes leak other information in addition to order information. In this study, a new database encryption scheme for DBaaS is proposed. The proposed scheme enables the execution of range queries without severe performance degradation and without leakage of information other than order information.
Impact of Acute Kidney Injury on Survival in Patients With Chronic Hepatitis C
( Hankyu Jeon ),( Jae Heon Kim ),( Sang Soo Lee ),( Hee Jin Kim ),( Ra Ri Cha ),( Hyun Chin Cho ),( Jae Min Lee ),( Chang Yoon Ha ),( Hyun Jin Kim ),( Tae Hyo Kim ),( Woon Tae Jung ),( Ok-jae Lee ) 대한간학회 2021 춘·추계 학술대회 (KASL) Vol.2021 No.1
A vector‑splitting method for neutral‑point voltage regulation in a three‑level inverter
Hankyu Hwang,Woosuk Lee,Yongsoon Park 전력전자학회 2022 JOURNAL OF POWER ELECTRONICS Vol.22 No.5
Neutral-point voltage regulation is one of the critical issues of a three-level inverter. This problem adversely affects the reliability of the power semiconductor. Zero-sequence voltage (ZSV) can be useful to regulate the neutral-point voltage in a three-level inverter. However, the regulating performance can be impeded by the change of the modulation index and the power factor. In this paper, a novel method is proposed to improve ZSV-based regulation. By aptly splitting a reference vector, the available range of the neutral-point current can be further stabilized at each operating point. It is detailed how to combine vector splitting with ZSV-based regulation. After the proposed method is discussed with simulation results for the entire first quadrant operation of an induction motor, its effectiveness is validated with experimental results under harsh operating conditions. As a result, the proposed method could effectively regulate the neutral-point voltage at various operating points and, in particular, could reduce neutral-point voltage ripples by 72.6% even under the worst condition.
Hankyu Kim,Yong Seok Nam,Yi-Suk Kim 대한해부학회 2021 Anatomy & Cell Biology Vol.54 No.1
Understanding anatomic variations in neurovascular structure inside the femoral triangle is crucial for regional anesthesiologists performing femoral nerve block. During routine dissection of a cadaver, an ascending branch of the lateral circumflex femoral artery with an anomalous course passing through the femoral nerve, specifically the posterior division, was identified inside the femoral triangle on the left thigh. The novel variation identified in this study occurred in an early stage of prenatal development. Recognition of this anatomic variation will be helpful for reducing unexpected complications during the femoral nerve block and the tensor fascia latae flap. Penetration of the posterior division of the femoral nerve by the arterial branch might cause pain or paresthesia of the medial aspect of the leg in the distribution of the saphenous nerve.
Analysis of Perusal Confirmation of Sharp Mail
Hankyu Joo 보안공학연구지원센터 2015 International Journal of Security and Its Applicat Vol.9 No.3
Sharp Mail was developed as a substitute for existing email systems and possesses several novel features. One such feature is the ability to generate a circulation confirmation document, which is to provide legal evidence of sent and received email. The crucial aspect of this document is perusal confirmation. Perusal confirmation certifies that the intended receiver of the message has read it. In this study, perusal confirmation is analyzed to determine whether it always contains correct information. This paper shows that perusal confirmation is not guaranteed always to contain correct information.
A Wideband Differential Low-Noise-Amplifier With IM3 Harmonics and Noise Canceling
Hankyu Lee,Taeyoung Chung,Heesong Seo,Inyoung Choi,Bumman Kim IEEE 2015 IEEE microwave and wireless components letters Vol.25 No.1
<P>This letter presents a wideband 2-stage differential LNA which utilizes the canceling techniques of IM3 harmonic distortion and noise. The 1st stage adopts a gm-boosted cross-coupled push-pull amplifier to achieve an input matching and reduce the NF. The 2nd stage simultaneously cancels the IM3 and thermal noise of the transistors in the 1st stage. The LNA has a gain of 16~18 dB in a wide bandwidth of 0.1~2.5 GHz, while consuming 13 mW from a 1.2 V power supply. The NF is 1.7~2.7 dB and IIP3/IIP2 are -3 ~ 0/18~21.5 dBm, respectively. The LNA is fabricated in 65 nm digital CMOS technology and the chip area is 0.008 mm<SUP>2</SUP>.</P>
Hankyu Lee,고혁완 생화학분자생물학회 2020 BMB Reports Vol.53 No.7
Cell cycle-related kinase (CCRK) has a conserved role in ciliogenesis, and Ccrk defects in mice lead to developmental defects, including exencephaly, preaxial polydactyly, skeletal abnormalities, retinal degeneration, and polycystic kidney. Here, we found that Ccrk is highly expressed in mouse trachea and bronchioles. Ccrk mutants exhibited pulmonary hypoplasia and abnormal branching morphogenesis in respiratory organ development. Furthermore, we demonstrated that Ccrk mutant lungs exhibit not only impaired branching morphogenesis but also a significant sacculation deficiency in alveoli associated with reduced epithelial progenitor cell proliferation. In pseudoglandular stages, Ccrk mutant lungs showed a downregulation of Hedgehog (Hh) signaling and defects in cilia morphology and frequency during progenitor-cell proliferation. Interestingly, we observed that activation of the Hh signaling pathway by small-molecule smoothened agonist (SAG) partially rescued bud morphology during branch bifurcation in explants from Ccrk mutant lungs. Therefore, CCRK properly regulates respiratory airway architecture in part through Hh-signal transduction and ciliogenesis.