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PATH AVERAGED OPTION VALUE CRITERIA FOR SELECTING BETTER OPTIONS
JUNSEOK KIM,MINHYUN YOO,HYEJU SON,SEUNGGYU LEE,MYEONG-HYEON KIM,YONGHO CHOI,DARAE JEONG,YOUNG ROCK KIM 한국산업응용수학회 2016 Journal of the Korean Society for Industrial and A Vol.20 No.2
In this paper, we propose an optimal choice scheme to determine the best option among comparable options whose current expectations are all the same under the condition that an investor has a confidence in the future value realization of underlying assets. For this purpose, we use a path-averaged option as our base instrument in which we calculate the time discounted value along the path and divide it by the number of time steps for a given expected path. First, we consider three European call options such as vanilla, cash-or-nothing, and asset-or-nothing as our comparable set of choice schemes. Next, we perform the experiments using historical data to prove the usefulness of our proposed scheme. The test suggests that the path-averaged option value is a good guideline to choose an optimal option.
van der Waals gap-inserted light-emitting p–n heterojunction of ZnO nanorods/graphene/p-GaN film
Sung Ho Moon,Junseok Jeong,Gwan Woo Kim,Dae Kwon Jin,Yong-Jin Kim,Jong Kyu Kim,Keun Soo Kim,Gunn Kim,Young Joon Hong 한국물리학회 2020 Current Applied Physics Vol.20 No.2
We report on the electroluminescent (EL) and electrical characteristics of graphene-inserted ZnO nanorods (NRs)/p-GaN heterojunction diode. In a comparative study, ZnO NRs/p-GaN and ZnO NRs/graphene/p-GaN heterojunctions exhibit white and yellow EL emissions, respectively, at reverse bias (rb) voltages. The different EL colors are results of different dichromatic EL peak intensity ratios between 2.25 and 2.8 eV light emissions which are originated from ZnO and p-GaN sides, respectively. The 2.25 eV EL is predominant in both the heterojunctions, because of recombination by numerous electrons tunneled from p-GaN to ZnO across the thin barriers of the staggered broken gap with a large band offset in ZnO/p-GaN and the van der Waals (vdW) gap formed by graphene insertion at ZnO NRs/p-GaN. However, as for the 2.8 eV EL intensity, ZnO NRs/graphene/p- GaN hardly shows the EL emission, whereas ZnO NRs/p-GaN exhibits the substantially strong EL peak. We discuss that the significantly reduced 2.8 eV EL emission of ZnO NRs/graphene/p-GaN is a result of decreased depletion layer thickness at p-GaN side where the recombination events occur for 2.8 eV EL before the reverse bias-driven tunneling because the insertion of graphene (or vdW gap barrier) inhibits the carrier diffusion whose amount determines the depletion thickness when forming the heterojunctions. This study opens a way of suppressing (or enhancing) the specific EL wavelength for the dichromatic EL-emitting heterojunctions simply by inserting atom-thick vdW layer.
Hyeon Ju JEONG,Eun-Jung KIM,Jung Yun KIM,Seok Won HAM,Sang-Hun CHOI,Nayoung HONG,Min Gi PARK,Junseok JANG,Sunyoung SEO,Sung-Ok KIM,Sung-Chan KIM,Hyunggee KIM 한국생물공학회 2021 한국생물공학회 학술대회 Vol.2021 No.10
The Jagged-1 (JAG1) is a Notch ligand that contact-dependently activates Notch receptors and regulates cancer progression. When Notch receptor activate, NOTCH intracellular domain (NICD) is released through proteolytic cleavage and forms transcription complex. Here, we show that JAG1 also releases JAG1 intracellular domain (JICD1) and JICD1 forms a transcription complex with DEAD-Box Helicase 17, SMAD Family Member 3, and TGFB induced factor homeobox 2. The JICD1 transcription complex binds to the promoter of Sex determining region Y-box 2 (SOX2) and regulates transcription of SOX2. JICD1 promotes acquisition of glioblastoma (GBM) stem cell properties by JICD1 transcription complex mediated SOX2 expression. JAG1 is highly expressed in GBM and induce reverse signal via JICD1 transcription complex. By regulating transcription of SOX2, JICD1 transcription complex is an important player in the maintenance of GBM properties. The inhibition of JICD1 transcription complex may be a novel strategy to target Notch signal.
A finite difference method for a conservative Allen–Cahn equation on non-flat surfaces
Kim, Junseok,Jeong, Darae,Yang, Seong-Deog,Choi, Yongho Elsevier 2017 Journal of computational physics Vol.334 No.-
<P><B>Abstract</B></P> <P>We present an efficient numerical scheme for the conservative Allen–Cahn (CAC) equation on various surfaces embedded in a narrow band domain in the three-dimensional space. We apply a quasi-Neumann boundary condition on the narrow band domain boundary using the closest point method. This boundary treatment allows us to use the standard Cartesian Laplacian operator instead of the Laplace–Beltrami operator. We apply a hybrid operator splitting method for solving the CAC equation. First, we use an explicit Euler method to solve the diffusion term. Second, we solve the nonlinear term by using a closed-form solution. Third, we apply a space–time-dependent Lagrange multiplier to conserve the total quantity. The overall scheme is explicit in time and does not need iterative steps; therefore, it is fast. A series of numerical experiments demonstrate the accuracy and efficiency of the proposed hybrid scheme.</P>
Kim Gwang Su,Kim Yong Ha,Choi Byung-Kyu,Hong Junseok,Ssessanga Nicholas 한국물리학회 2021 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.79 No.8
The four-dimensional variational (4D-VAR) technique, originally developed for weather forecasting applications, has been utilized in a data-assimilated model to estimate rocket exhaust emission from observed ionospheric disturbances. In this study, we improved the 4D-VAR method by utilizing a more realistic chemical model in the ionosphere and applied it to characterize ionosphere disturbances caused by the Hwasung-15 (H-15) rocket exhaust chemicals. The H-15 rocket was launched southeastward from North Korea at 18:17 UT on 28 November 2017. During the first hours of the launch, the total electron content (TEC) derived from the Korean ground-based GNSS receiver network exhibited ionospheric disturbances along the Rocket’s trajectory. The disturbances were most distinct along the GLONASS (Global Orbiting Navigational Satellite System) line of site. By assimilating the measured TEC data into the 4D-VAR model, we were able to characterize the ionospheric depletion and recovery with respect to the standard ionospheric model, IRI-2016. In addition, the rocket exhaust emissions were estimated to be ~ 1.5 × 1027 molecules per sec, with a number ratio of 2:1 for water to hydrogen in the rocket’s exhaust gas.
Deep Reinforcement Learning for Traffic Signal Control Considering Adjacent Intersection States
Junseok Kim,Hwasoo Yeo 대한교통학회 2022 대한교통학회 학술대회지 Vol.87 No.-
Recently, various studies have been conducted on reinforcement learning for traffic signal control. However, these studies have a limited environment and didnt consider the perspective of drivers. It will be possible to operate a coordinated signal for the drivers predictability and a cycle with a realistic minimum green time. In this study, to achieve these two objectives, we studied whether the coordinated signal situation can be learned considering the state of the adjacent intersection. Reinforcement learning is used for optimization, the state of adjacent intersections was reflected and an appropriate reward was found. In addition, more methodologies for coordination and actual road network data will be applied. It is expected that future research can be expanded to a multi-intersection environment and intersections between coordinated arteries to progress vehicles.
Kim, Hyobong,Yeom, Hankil,Choo, Sangyoon,Kim, Jongwoo,Park, Jiho,In, Sehwan,Hong, Yong-Ju,Park, Seong-Je,Ko, Junseok 한국초전도저온공학회 2020 한국초전도저온공학회논문지 Vol.22 No.4
This paper describes the real operation of 2 kW class reverse-Brayton refrigeration system with neon as a working fluid. The refrigeration cycle is designed with operating pressure of 0.5 and 1.0 MPa at low and high pressure side, respectively. Compressor package consists of several helium scroll compressors witch are originally used for driving GM cryocooler. Three segments of plate heat exchanger are adopted to cover the wide temperature range and the refrigeration power is produced by turbo expander. The developed refrigeration system is successfully operated at its target temperature of 77 K. In experiments, all parameters such as pressure, temperature, mass flow rate and valve opening are measured to investigate characteristics during cool-down process and normal state. The difference between design and real operation is discussed with measured experimental data. At normal state of 77 K operation, the developed reverse-Brayton refrigeration system shows 1.83 kW at 68.2 K of cold-end temperature.