Pressure Induced Structural Changes of Proteins Affecting the Ice Nucleation Temperature of Pork Loins

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.

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>

Enhanced Thermoelectric Performance of Bar-Coated SWCNT/P3HT Thin Films

Lee, Woohwa,Hong, Cheon Taek,Kwon, O Hwan,Yoo, Youngjae,Kang, Young Hun,Lee, Jun Young,Cho, Song Yun,Jang, Kwang-Suk American Chemical Society 2015 ACS APPLIED MATERIALS & INTERFACES Vol.7 No.12

<P>The influence of processing conditions, such as ink concentration and coating method, on the thermoelectric properties of SWCNT/P3HT nanocomposite films was investigated systematically. Using simple wire-bar-coating, SWCNT/P3HT nanocomposite films with high thermoelectric performance could be obtained without additional P3HT doping. The wire-bar-coated SWCNT/P3HT nanocomposite films exhibited power factors of up to 105 μW m<SUP>–1</SUP> K<SUP>–2</SUP> at room temperature. The SWCNT bundles with diameters in the range of 6–23 nm formed an interconnected network in the wire-bar-coated nanocomposite films. Network formation in these nanocomposite films was expected to be strongly related to the development of electrical pathways due to inter-SWCNT bundle connections. This study suggests that the thermoelectric performance of SWCNT/P3HT nanocomposite films could be optimized by controlling their processing conditions and morphology.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/aamick/2015/aamick.2015.7.issue-12/acsami.5b00626/production/images/medium/am-2015-00626r_0011.gif'></P>

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.

Lithography-Free Fabrication of Large Area Subwavelength Antireflection Structures Using Thermally Dewetted Pt/Pd Alloy Etch Mask

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>

Surface Viscoelasticity of an Organic Interlayer Affects the Crystalline Nanostructure of an Organic Semiconductor and Its Electrical Performance

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>

Design and Validation of a UAM Integrated Traffic Management System (UIMS) for Operations

Youngjae Lee,Chan Gwak,Taeho Kwag,Kyu Ri Park,Sangyeul Bae,Juwon Lee,Hyeon Jun Lee,Jae-Woo Lee 한국항공우주학회 2022 한국항공우주학회 학술발표회 논문집 Vol.2022 No.11

Comparison of the physicochemical properties of fermented squid sauce supplemented with vitamin C and commercial low-salt soy sauces

Youngjae Cho,Junggyu Lee,Yoon Jung Lee,HeeJeong Choi,SangYoon Lee,Dong Hyeon Park,JingJing Bai,Eunji Kwak,Junhwan Bae,Honggyun Kim,Mi-Jung Choi 한국산업식품공학회 2017 학술대회 및 심포지엄 Vol.2017 No.11

Salt is generally used for food seasonings and preservations as a common ingredient. However, excess salt intake has generated health issues such as high blood pressure, osteoporosis, stroke, and heart diseases. Recently, desires and interests of low-salt cooking have been increased among people who want healthy diets. The aim of study was to compare the physicochemical characteristics of a fermented squid sauce added with vitamin C and commercial low-salt soy sauces. Thawed and crushed squids were fermented until the solid squid became liquid at 25°C with an addition of 5% (g/g) vitamin C. Then, fermented squid sauce was heated at 100°C for 30 min and filtered. All samples were measured in multiple aspects of amino acid nitrogen, salt, sugar and water content, pH, chromaticity and brown color, and sensory test. In the results, color values showed no significantly difference between all the samples (p>0.05). Water content value of the fermented squid sauce was the highest among samples. Brown color, salt contents and sugar contents of the fermented squid sauce were significantly different than other low salt soy sauces with an exception of the sauce made with functional salt. These results showed a similar tendency as those of sensory evaluation. As conclusion, the possibility of fermented squid sauce added with vitamin C showed a possibility as a candidate of low-salt soy sauce.

Correlation between postpartum depression and premenstrual dysphoric disorder: Single center study

( Youngjae Lee ),( Sangwook Yi ),( Dahye Ju ),( Sangsoo Lee ),( Wooseok Sohn ),( Inju Kim ) 대한산부인과학회 2015 Obstetrics & Gynecology Science Vol.58 No.5

To describe the prevalence and correlates of the postpartum depression and premenstrual dysphoric disorderOne hundred sixty six women were assessed around 10th to 14th days after delivery in Gangneung Asan Hospital, Korea, from September 2011 to March 2012. We checked their risk factors for postpartum depressive disorders using the Beck Depression Inventory and the Edinburgh Postnatal Depression Scale. Premenstrual dysphoric disorder was evaluated retrospectively and was defined as having more than 5 of the following 10 symptoms: breast tenderness, bloating, headache, peripheral edema (hand and foot), depressive symptoms, anger, irritability, anxiety, oversensitivity, and exaggerated mood swings.The prevalence rate of postpartum depression using the Edinburgh Postnatal Depression Scale ≥10 and Beck Depression Inventory ≥10 was 13.9% (23/166). We found statistical differences (P<0.01) between the postpartum depression group and the postpartum non-depression group in smoking history, past history of psychiatric problems, and level of marital satisfaction. The prevalence rate of premenstrual syndrome (PMS) was 9% (15/166) and among 23 women in the postpartum depression group, eight were determined to have premenstrual dysphoric disorder, yielding a prevalence rate of 34.8% (8/23). Among 143 women in the postpartum non-depression group, seven were determined to have PMS, yielding a prevalence rate of 4.9% (7/143). A correlation between postpartum depression and PMS was thus found (P<0.01).PMS appears to be associated with postpartum depression. This means that a hormone-related etiology appears to be one risk factor for postpartum depression.

DSC and physical property analysis by mixed ratio of mixed vegetable oil and temperature

Youngjae Cho,Honggyun Kim,Eunji Kwak,Junggyu Lee,Junhwan Bae,SangYoon Lee,Yoon Jung Lee,HeeJeong Choi,Dong Hyeon Park,JingJing Bai,Mi-Jung Choi 한국산업식품공학회 2017 학술대회 및 심포지엄 Vol.2017 No.11

In this study, we investigated the change of physical properties associated with the temperature of vegetable mixed oil and fat in order to produce vegetable oil and fat suitable for plant meat production. The canola oil and coconut oil were mixed at various weight ratios, and the phase change temperatures by the ratio of two oils were measured using the differential scanning calorimetry (DSC). Storage modulus (G'), loss modulus (G") and viscosity were measured using a rheometer at 20-40°C and 0.4 Hz-100 Hz. Storage modulus (G') at constant frequency (10 Hz) was measured in a continuous section of 10-50°C. As the coconut oil content increased, the peak of the melting point moved to the lower side. The viscosity was higher in order of canola oil, mixed oil, and coconut oil, and the viscosity showed a tendency to decrease as the temperature increased. In the liquid state, it showed a tendency to increase after the value of storage modulus (G') and loss modulus (G") decreased from 0.634 Hz-1 Hz. The conversion time point of storage modulus (G') of continuous temperature change is consistent with the melting point temperature of DSC, as the passed start at 10°C, storage modulus (G') increased with an exception of canola oil. Using these results, we will pursue to produce a mixed plant oil applicable to the production of vegetable meat.