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Park Yeong-Ju,Hwang Unsik,Park Suyeon,Sim Sol,Jeong Soyeon,Park Misun,Kang Minji,Lee Youngsoo,Song Youngju,Park Hoon,Suh Hee-Jae 한국응용생명화학회 2021 Applied Biological Chemistry (Appl Biol Chem) Vol.64 No.1
Compound K (CK; 20-O-β-(d-glucopyranosyl)-20(S)-protopanaxadiol) is one of the metabolites of ginsenosides contained in red ginseng (RG) and is known to have high bioavailability. This study aimed to establish the optimal conditions for enzyme treatment to convert ginsenosides from RG extract to CK, and to prove the characteristics of bioconverted red ginseng (BRG) extract. CK was not detected in unenzyme-treated RG extract, and in the single-step enzyme treatment, it was produced at less than 4.58 mg/g only in treatment group with Pyr-flo or Sumizyme AC (at 50 °C for 48 h). The highest yield of CK (14.32 mg/g) was obtained by Ultimase MFC treatment at 50 °C for 48 h after treatment with a mixture of Pyr-flo and Rapidase at 50 °C for 24 h. Total polyphenol, 2,2-diphenyl-1-picrylhydrazyl (DPPH), and 2,2-azinobis-(3-ethylbenzothiazoline-6-sulfonic acid)) (ABTS) radical scavenging activity were higher in BRG than in RG (p < 0.5). High-fat diet (HD) rat fed 1% BRG had significantly lower body weight, heart weight, fat pads (periosteal fat, epididymal fat), serum glucose levels, and hepatic triglyceride levels than those HD rat fed 1% RG (p < 0.05). In conclusion, the sequential enzymatic bioconversion was produces higher CK in RG root extract than single-step enzyme treatment.
PSO알고리즘을 이용한 전력계통의 발전기 예방정비계획 수립
박영수(Youngsoo Park),정희명(Heemyung Jeong),박종국(Jongkook Park),김진호(Jinho Kim),박준호(Juneho Park) 대한전기학회 2007 대한전기학회 학술대회 논문집 Vol.2007 No.11
This paper focuses on maintenance scheduling using PSO algorithm for power plants from an economic (operating cost) and reliable(variance of operating reserve margin) point of view. We also apply regional reserve margin and transfer capability to maintenance scheduling problem. The proposed method has been applied to IEEE-RTS(1996) with 32-generators and a real -world large scale power system with 291 generators.
Importance-Performance Analysis (IPA) of Cyber Security Management: Focused on ECDIS User Experience
Park, Sangwon,Chang, Yeeun,Park, Youngsoo The Korean Society of Marine Environment and safet 2021 海洋環境安全學會誌 Vol.27 No.3
The mandatory installation of the ECDIS (Electronic Chart Display and Information System) became an important navigational equipment for navigation officer. In addition, ECDIS is a key component of the ship's digitalization in conjunction with various navigational equipment. Meanwhile, cyber-attacks emerge as a new threat along with digitalization. Damage caused by cyber-attacks is also reported in the shipping sector, and IMO recommends that cybersecurity guidelines be developed and included in International Security Management (ISM). This study analyzed the cybersecurity hazards of ECDIS, where various navigational equipment are connected. To this end, Importance-Performance Analysis (IPA) was conducted on navigation officer using ECDIS. As a result, the development of technologies for cyber-attack detection and prevention should be priority. In addition, policies related to 'Hardware and Software upgrade', 'network access control', and 'data backup and recovery' were analyzed as contents to be maintained. This paper is significant in deriving risk factors from the perspective of ECDIS users and analyzing their priorities, and it is necessary to analyze various cyber-attacks that may occur on ships in the future.
Effects of diesel fuel temperature on fuel flow and spray characteristics
Park, Youngsoo,Hwang, Joonsik,Bae, Choongsik,Kim, Kihyun,Lee, Jinwoo,Pyo, Soonchan Elsevier 2015 Fuel Vol.162 No.-
<P><B>Abstract</B></P> <P>The cold start issue has been a problem in diesel engines. Thus, in the present research, the diesel fuel flow and macroscopic spray characteristics over a wide fuel temperature range were investigated to provide valuable insights for solving the cold start problem. An injection system including a common-rail and a fuel supplier was designed to control the fuel temperature from 243K to 313K. For the fuel flow characteristics, the results showed that the injection quantity decreased by 50% as the fuel temperature decreased from 313K to 243K under the same energizing time. It was also confirmed that the real start of injection timing was retarded as the fuel temperature decreased. The reason is that increased fuel viscosity disturbed the injector needle motion and fuel flow in the nozzle. The spray test was performed under the simulated cold start condition using a constant-volume combustion chamber (CVCC). For the macroscopic spray characteristics, the liquid-phase fuel penetration increased and the spray angle decreased with cold fuel due to attenuated fuel evaporation process and interaction with ambient gas. These results could cause poor air–fuel mixing process under the cold starting.</P>
Park, Jun-Hyun,Jeon, Kichan,Lee, Sangwon,Kim, Sangwook,Kim, Sunil,Song, Ihun,Park, Jaechul,Park, Youngsoo,Kim, Chang Jung,Kim, Dong Myong,Kim, Dae Hwan The Electrochemical Society 2010 Journal of the Electrochemical Society Vol.157 No.3
<P>The self-consistent technique for extracting density of states [DOS: [Formula]] in an amorphous indium gallium zinc oxide (a-IGZO) thin film transistor is proposed and demonstrated. The key parameters are the [Formula] of the a-IGZO active layer and the intrinsic channel mobility [Formula]. While the energy level [Formula] is scanned by the photon energy and gate-to-source voltage [Formula] sweep, its density is extracted from an optical response of capacitance–voltage characteristics. Using the [Formula]-dependent [Formula] as another boundary condition, a linearly mapped DOS assuming a linear relation between [Formula] and [Formula] is translated into a final DOS by fully considering a nonlinear relation between [Formula] and [Formula]. The final DOS is finally extracted and verified by finding the self-consistent solution satisfying both the linearly mapped DOS and the measured [Formula] dependence of [Formula] with the numerical iteration of a DOS-based [Formula] model. The extracted final DOS parameters are [Formula], [Formula], [Formula], [Formula], and [Formula] with the formula of exponential tail states and Gaussian deep states.</P>
Enhanced Chemical Reactivity of Graphene by Fermi Level Modulation
Park, Myung Jin,Choi, Hae-Hyun,Park, Baekwon,Lee, Jae Yoon,Lee, Chul-Ho,Choi, Yong Seok,Kim, Youngsoo,Yoo, Je Min,Lee, Hyukjin,Hong, Byung Hee American Chemical Society 2018 Chemistry of materials Vol.30 No.16
<P>Among various approaches to modify the electronic and chemical properties of graphene, functionalization is one of the most facile ways to tailor these properties. The rearranged structure with covalently bonded diazonium molecules exhibits distinct semiconducting property, and the attached diazonium enables subsequent chemical reactions. Notably, the rate of diazonium functionalization depends on the substrate and the presence of strain. Meanwhile, according to the Gerischer-Marcus theory, this reactivity can be further tuned by adjusting the Fermi level. Here, we precisely controlled the Fermi level of graphene by introducing the self-assembled monolayer (SAM) and investigated the degree of chemical reactivity of graphene with respect to the doping types. The n-doped graphene exhibited the highest reactivity not only for diazonium molecules but also for metal ions. The increased reactivity is originated from a remarkable electron donor effect over the entire area. In addition, the n-doped graphene enabled spatially patterned functionalization of diazonium molecules, which was further utilized as a growth template for gold particles that would be advantageous for enhanced electrochemical reactivity.</P> [FIG OMISSION]</BR>
Park, Jun Hyuk,Lin, Guan-Bo,Kim, Dong Yeong,Lee, Jong Won,Cho, Jaehee,Kim, Jungsub,Lee, Jinsub,Kim, Yong-Il,Park, Youngsoo,Schubert, E Fred,Kim, Jong Kyu Optical Society of America 2015 Optics express Vol.23 No.12
<P>The efficiency of an AlGaN deep-ultraviolet light-emitting diode with peak emission wavelength of 285 nm is investigated as a function of current over a wide range of temperatures (110 K to 300 K). We find that the efficiency-versus-current curve exhibits unique and distinct features over the entire temperature range including three points of inflection. At low temperatures, the change in slope in the efficiency-versus-current curve is particularly pronounced producing a minimum in the efficiency after which the efficiency rises again. Furthermore, at high current density, the low-temperature efficiency exceeds the room-temperature efficiency. The feature-rich efficiency-versus-current curve is consistent with an enhancement in p-type conductivity by field-ionization of acceptors that occurs in the high-injection regime and is particularly pronounced at low temperatures. Differential conductivity measurements show a marked rise in the high-injection regime that is well correlated to the minimum point in the efficiency-versus-current curve.</P>
Park, Jae Chul,Kim, Sangwook,Kim, Sunil,Kim, Changjung,Song, Ihun,Park, Youngsoo,Jung, U‐,In,Kim, Dae Hwan,Lee, Jang‐,Sik WILEY‐VCH Verlag 2010 Advanced Materials Vol.22 No.48
<P><B>A novel device structure</B> is presented for amorphous oxide semiconductor thin‐film transistors with high performance as well as improved electrical/optical stress stability. The highly stable transistor devices are developed using composition‐modulated dual active layers. This approach could potentially be used to fabricate product‐level display devices using amorphous oxide semiconductors in the near future. </P>