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<small>FeSSD</small>: A Fast Encrypted SSD Employing On-Chip Access-Control Memory
Lee, Junghee,Ganesh, Kalidas,Lee, Hyuk-Jun,Kim, Youngjae IEEE 2017 IEEE computer architecture letters Vol.16 No.2
<P>Cryptography is one of the most popular methods for protecting data stored in storage devices such as solid-state drives (SSDs). To maintain integrity of data, one of the popular techniques is that all incoming data are encrypted before they are stored, however, in this technique, the encryption overhead is non-negligible and it can increase I/O service time. In order to mitigate the negative performance impact caused by the data encryption, a write buffer can be used to hide the long latency by encryption. Using the write buffer, incoming unencrypted data can be immediately returned as soon as they are written in the buffer. They will get encrypted and synchronized with flash memory. However, if the write buffer itself is not encrypted, unencrypted secret data might leak through this insecure write buffer. On the other hand, if the entire write buffer is fully encrypted, it incurs significant performance overhead. To address this problem, we propose an on-chip access control memory (ACM) and presents a fast encrypted SSD, called <SMALL>FeSSD</SMALL> that implements a secure write buffering mechanism using the ACM. The ACM does not require a memory-level full encryption mechanism, thus not only solving the unencrypted data leaking problem, but also offering relatively fast I/O service. Our simulation results show that the I/O response time of <SMALL>FeSSD</SMALL> can be improved by up to 56 percent over a baseline where encrypted data are stored in the normal write buffer.</P>
Youngjae Cho,Eun-Jung Lee,Jiseon Lee,SangYoon Lee,Young-Chan Yun,Geun-Pyo Hong 한국축산식품학회 2019 한국축산식품학회지 Vol.39 No.6
This study investigated the effects of pressure-mediated protein changes on the ice nucleation temperature of pork loins. To variate chemical state of meat proteins, pork loin was pressurized at varying pressure levels (100–500 MPa) for 3 min, and moisture content, expressible moisture (EM) and differential scanning calorimetry (DSC) were analyzed. Although, all treatments showed similar moisture content, EM and degree of protein unfolding of pork loin showed different features as of 300 MPa. At moderate pressure treatments (100–200 MPa), all protein fractions were detected in DSC experiments, and pork loin had lower EM than control (p<0.05). Meanwhile, myosin and actin of pork loin treated at greater than 300 MPa were completely unfolded, and the treatments showed high EM compared to control (p<0.05). Unfolding of meat proteins was a factor suppressing ice nucleation, and the ice nucleation temperature tended to decrease with increasing applied pressure level. The ice nucleation characteristics of pressurized pork loin exhibited a potential application in freezing storage of pressurized meat with less tissue damage comparing to freeze fresh meat, and further exploration regarding the quality change after freezing of fresh and pressurized meat was warranted.
Lee, Youngjae,Jang, Jungwoo,Yoon, Jinho,Choi, Jeong-Woo,Choi, Inhee,Kang, Taewook The Royal Society of Chemistry 2019 Chemical communications Vol.55 No.22
<P>A phase transfer-mediated ligand exchange method is developed for highly selective and rapid synthesis of colloidal phospholipid bilayer-coated gold nanocrystals. The complete replacement of strongly bound surface ligands such as cetyltrimethylammonium bromide (CTAB) and citrate by phospholipid bilayer can be quickly achieved by water-chloroform phase transfer.</P>
Lee, Hwa Sung,Kang, Moon Sung,Kang, Sung Kyung,Kim, Beom Joon,Yoo, Youngjae,Lim, Ho Sun,Um, Soong Ho,Ryu, Du Yeol,Lee, Dong Ryeol,Cho, Jeong Ho American Chemical Society 2012 The Journal of Physical Chemistry Part C Vol.116 No.41
<P>We demonstrated that the viscoelasticity of a dielectric surface affected the overlying pentacene crystalline nanostructures and the electrical performances of pentacene-based field-effect transistors (FETs). The surface viscoelasticities of the gate dielectrics were systematically controlled by varying the polymer chain lengths of polystyrene brushes (<I>b</I>-PSs) and the substrate temperature during pentacene deposition. The <I>b</I>-PSs were chosen as a model surface because the glass–liquid transition affected neither the surface energy nor the surface roughness. Moreover, the glass–liquid transition temperature increased with increasing <I>b</I>-PS chain length. The liquid-like <I>b</I>-PS chains disturbed the surface arrangement of the pentacene molecules, which reduced the organization of the crystalline structures, yielding smaller grains during the early stages of pentacene growth. The dramatic changes in the film morphology and crystalline nanostructures above the <I>b</I>-PS glass–liquid transition resulted in noticeable changes in the OFET performance. The systematic investigation of the dielectric surface viscoelasticity presented here provides a significant step toward optimizing the nanostructures of organic semiconductors, and thereby, the device performance, by engineering the interfaces in the OFETs.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/jpccck/2012/jpccck.2012.116.issue-41/jp305820r/production/images/medium/jp-2012-05820r_0007.gif'></P>
Lee, Youngjae,Koh, Kisik,Na, Hyungjoo,Kim, Kwanoh,Kang, Jeong-Jin,Kim, Jongbaeg Springer 2009 NANOSCALE RESEARCH LETTERS Vol.4 No.4
<P>We have demonstrated lithography-free, simple, and large area fabrication method for subwavelength antireflection structures (SAS) to achieve low reflectance of silicon (Si) surface. Thin film of Pt/Pd alloy on a Si substrate is melted and agglomerated into hemispheric nanodots by thermal dewetting process, and the array of the nanodots is used as etch mask for reactive ion etching (RIE) to form SAS on the Si surface. Two critical parameters, the temperature of thermal dewetting processes and the duration of RIE, have been experimentally studied to achieve very low reflectance from SAS. All the SAS have well-tapered shapes that the refractive index may be changed continuously and monotonously in the direction of incident light. In the wavelength range from 350 to 1800 nm, the measured reflectance of the fabricated SAS averages out to 5%. Especially in the wavelength range from 550 to 650 nm, which falls within visible light, the measured reflectance is under 0.01%.</P>
A STUDY ON A FIRE-ALARM SYSTEM USING ZIGBEE
YoungJae Lee,JinHo Park,ChoongWon Chang,MinSoo Jung 한국멀티미디어학회 2007 한국멀티미디어학회 국제학술대회 Vol.2007 No.-
We designed a ubiquitous fire alarm system integrate with ZigBee of local area wireless communication technology. If we realize the foundation of this technology, in addition to the specialized regions, we can also realize the movable fire alarm system. In some sensitive places such as the movable ignition depository. the sensitive depository of chemical materials and so on. fire cannot be happened absolutely, if we set the movable fire alarm, the maximal effectiveness will be displayed.
Characteristics and distribution of terpenes in South Korean forests
Lee, Jaeseok,Cho, Kyoung Sang,Jeon, Youngjae,Kim, Ji Beom,Lim, Young-ran,Lee, Kyungho,Lee, Im-Soon The Ecological Society of Korea 2017 Journal of Ecology and Environment Vol.41 No.5
The importance of forests continues to increase throughout the world, and one of the reasons is that a forest is a major place to emit terpenes, which have been reported to be beneficial to human health. In South Korea, forests occupy about 64% of the total land area and consist mainly of pine and oak trees. Since only a limited number of forests have been analyzed to date, a comprehensive understanding of terpenes emitted from regional forests remains in its infancy in Korea. Here, to gain insights into terpenes from regional forests located in South Korea, we review the characteristics of Korean forests and recent studies on major terpenes emitted from regional forests as well as from native trees dominant in South Korea. We also discuss meteorological factors that affect the terpene emissions in Korean forests. In conclusion, 18 types of terpenes were detected in Korean forests and their compositions in different forests are largely dependent on the dominant plant species in the forest. Moreover, terpene emissions in Korean forests are affected by various environmental factors, including temperature, amount and duration of daylight, season, and age of trees. To improve the understanding of the characteristics of terpene distribution, more studies are required on the terpene production of Korean forests in various regions.
Zombie Chasing: Efficient Flash Management Considering Dirty Data in the Buffer Cache
Youngjae Lee,Jin-Soo Kim,Sang-Won Lee,Seungryoul Maeng IEEE 2015 IEEE TRANSACTIONS ON COMPUTERS - Vol.64 No.2
<P>This paper presents a novel technique, called Zombie Chasing, for efficient flash management in solid state drives (SSDs). Due to the unique characteristics of NAND flash memory, SSDs need to accurately understand the liveness of the data stored in themselves. Recently, the TRIM command has been introduced to notify SSDs of dead data caused by file deletions, which otherwise could not be tracked by SSDs. This paper goes one step further and proposes a new liveness state, called the zombie state, to denote live data that will be dead shortly due to the corresponding dirty data in the buffer cache. We also devise new zombie-aware garbage collection algorithms which utilize the information about such zombie data inside SSDs. To evaluate Zombie Chasing, we implement zombie-aware garbage collection algorithms in the prototype SSD and modify the Linux kernel and the Oracle DBMS to deliver the information on the zombie data to the prototype SSD. Through comprehensive evaluations using our in-house micro-benchmark and the TPC-C benchmark, we observe that Zombie Chasing improves SSD performance effectively by reducing garbage collection overhead. Especially, our evaluation with the TPC-C benchmark on the Oracle DBMS shows that Zombie Chasing enhances the Transactions Per Second (TPS) value by up to 22% with negligible overhead.</P>