Verification of 1-g Shaking Table Test Using Laminar Shear Box by Numerical Modeling

( Yonghee Lee ),( Hak-sung Kim ),( Weon-hack Choi ),( Seok-chul Kim ) 대한지질공학회 2019 대한지질공학회 학술발표회논문집 Vol.2019 No.2

The most accurate results on soil amplification can be obtained from full-scale model. However, it is often impractical because of the cost of full scale model and the natural uncertainty of earthquake occurrence. Therefore, lab-scale physical modeling such as 1-g shaking table and centrifuge tests are widely performed to determine the effect of ground motion during earthquake. Meanwhile, the boundary effect is one of the major limitation in lab-scale physical model. In this study, laminar shear box (LSB) to minimize the boundary effect was developed, and the capacity of developed LSB was evaluated using preliminary 1-g shaking table test. LSB is composed of a stack of aluminum frames. Ball bearings between the aluminum frames allow the lateral displacement of the box corresponding soil deformation during the dynamic loading time. The height, length, and width of LSB are 2,000, 600 and 600 mm, respectively. Sine sweep test (from 2 Hz to 30 Hz) was conducted to determine the response characteristic of LSB. Furthermore, numerical modeling was performed using the DEEPSOIL version 7.1, and FLAC 2D software. LSB shaking table test results on center and boundary area of LSB are well matched with the numerical analyses results. However, response of boundary area is slightly larger than that of center area. It seems that this phenomenon is induced by the inevitable partial reflection of the seismic wave at the boundary. The test results show that LSB greatly mitigate the boundary effect of the lab-scale physical modeling in comparison to conventional rigid box (RB).

Ordinary People"s Tragedy : Comparative Study of Plays of Arthur Miller and Beomsuk Cha

Yonghee Lee 한국영어어문교육학회 2007 영어어문교육 Vol.13 No.1

  The main concern of the study is the playwrights’ perspectives toward the relationship between society and individuals rather than specific cultural or social circumstances. This study is justified in that the similarities of both playwrights not only provide an opportunity to bridge two different cultures, but they also help readers understand another culture and deepen the understanding of their own culture in the map of international literature. In their plays, both Miller and Cha express an individual’s or a family’s frustration, conflict, pleasure, and hope as reflected in the social circumstances. The characters take ideas and values from their social world and thrive or fail. Specifically, I have focused on three elements--obsession, generational value systems, and alienation. With three common features, I examine how closely Miller and Cha deal with ordinary people’s tragedies.

Solution processible MoO_x-incorporated graphene anode for efficient polymer light-emitting diodes

Lee, Dongchan,Kim, Donghyuk,Lee, Yonghee,Young Jeon, Duk IOP 2017 Nanotechnology Vol.28 No.23

<P>Graphene has attracted great attention owing to its superb properties as an anode of organic or polymer light-emitting diodes (OLEDs or PLEDs). However, there are still barriers for graphene to replace existing indium tin oxide (ITO) due to relatively high sheet resistance and work function mismatch. In this study, PLEDs using molybdenum oxide (MoO<SUB>x</SUB>) nanoparticle-doped graphene are demonstrated on a plastic substrate to have a low sheet resistance and high work function. Also, this work shows how the doping amount influences the electronic properties of the graphene anode and the PLED performance. A facile and scalable spin coating process was used for doping graphene with MoO<SUB>x</SUB>. After doping, the sheet resistance and the optical transmittance of five-layer graphene were ∼180 Ω sq<SUP>−1</SUP> and ∼88%, respectively. Moreover, the surface roughness of MoO<SUB>x</SUB>-doped graphene becomes smoother than that of pristine graphene. Furthermore, a nonlinear relationship was observed between the MoO<SUB>x</SUB> doping level and device performance. Therefore, a modified stacking structure of graphene electrode is presented to further enhance device performance. The maximum external quantum efficiency (EQE) and power efficiency of the PLED using the MoO<SUB>x</SUB>-doped graphene anode were 4.7% and 13.3 lm W<SUP>−1</SUP>, respectively. The MoO<SUB>x</SUB>-doped graphene anode showed enhanced device performance (261% for maximum EQE, 255% for maximum power efficiency) compared with the pristine graphene.</P>

Comparison of Nonlinear Analysis and Equivalent Linear Analysis on 1D Site Response Analysis

( Yonghee Lee ),( Hak-sung Kim ),( Seok-chul Kim ),( Weon-hack Choi ) 대한지질공학회 2019 대한지질공학회 학술발표회논문집 Vol.2019 No.2

Equivalent linear and nonlinear analyses are the most common approaches to perform 1D site response analysis. Since these methods have inherent differences in analysis process (time domain, frequency domain), computed results yield different output. Equivalent linear analysis is a kind of linear analysis considering non-linearity and an approximation of hysteric soil behavior. Nonlinear analysis method is the hysteretic stress-strain response of soil and can represent more actual behavior rather than equivalent linear analysis. In this study 1D nonlinear analysis and equivalent linear analysis are performed with DEEPSOIL version 7.1 for 30 m soil depth. Shear modulus reduction and damping curve was used with Darendeli (2001) that has Ko is 0.5. Curve fitting for modulus reduction and damping function were performed with university of Illinois at Urbana-Champaign (MRDF-UIUC) model. Used soil model is pressure-dependent modified Kondner Zelasko (MKZ) and hysteretic unloading-reloading formulation follows non-masing rule in the nonlinear analyses. The thickness of each layer is 1 m. The used input motion is Northridge earthquake record (scaled from 0.05 g to 1 g). Analyses results show that ground behavior is very similar in the low peak ground acceleration (PGA) level but somewhat different in the high PGA level. In case of strong motion (i.e., PGA > 0.5 g) especially in the initial and decayed part, equivalent linear analyses results show under-prediction tendency but over-prediction tendency in the strong motion part. During strong motion part, soil stiffness decreased in the nonlinear analysis but is same in the equivalent linear analysis.

Universality of Carnivalesque Aspects

Lee, Yonghee(이용희) 한국동서비교문학학회 2010 동서 비교문학저널 Vol.0 No.22

  In his influential book, Rabelais and His World, Bakhtin explicates the features of carnival in the medieval era in terms of its subversiveness and temporary suspension of social hierarchy. Carnival appeared to be quite radical and dangerous to the dominant class. Yet, there were a number of carnivalesque feasts during the medieval era. It is because a two-world condition that Bakhtin articulates. These feasts engendered a “second world and a second life outside officialdom [. . .] in which [people] lived during a given time of the year”(6). This study aims to examine carnivalesque aspects as universal feature found in festivals of both Europe and Korea.   The feast of the Boy Bishop, was held as one of the pious feasts by the church. This feast was designed to celebrate the innocence of children based on the Bible. However, now that a boy played a religious role of a bishop, this feast possessed carnivalesque factors innately. Henceforth, as time went, this holy feast was deviated from its original purpose, instead, it became burlesque.   Likewise, Bongsan TalChum, a Korean mask dance, demonstrates similar aspects to the feast of the Boy Bishop. Bongsan TalChum originated from a form of ritual to ward off the evil spirit and later on became a folk festival because of its carnivalesque narratives. Performing a mask dance in itself creates festive atmosphere for the town people and the storyline of Bongsan TalChum contains the subversion of the social hierarchy, which gives the people a good deal of carnivalesque laughter.   Both carnivalesque festivals, the feast of the Boy Bishop and Bongsan TalChum, enabled the lower class to live in an equal and utopian community in spite of their temporariness. During these festivals, all the social status were suspended and the people became “social others,” which was impossible in reality. It is remarkable that the medieval feast and Korean mask dance demonstrate similar aspects of carnival.

Reduced Pyronin B as a solution-processable and heating-free n-type dopant for soft electronics

Lee, Eun Kwang,Kim, Yonghee,Back, Jisu,Lee, Eunsung,Oh, Joon Hak The Royal Society of Chemistry 2018 Journal of Materials Chemistry C Vol.6 No.25

<P>Air-stable and heating-free doping processes are highly desirable for realizing advanced flexible electronics on plastic substrates. A synthetic protocol for a high-performance n-type organic dopant using an organic cationic dye, Pyronin B, <I>via</I> a simple chemical reduction method with NaBH4 in various organic non-polar solvents is developed, in which the cationic dye Pyronin B is transformed into its leuco form. The reduced Pyronin B (rPyB, leuco form) spontaneously interacts with carbon nanomaterials, such as graphene and [6,6]-phenyl-C61-butyric acid methyl ester (PCBM), <I>via</I> hydride-mediated electron transfer doping, which is confirmed by electron spin resonance (ESR) analysis. After coating rPyB onto graphene, the non-polar solvents are removed by simple evacuation (∼1 × 10<SUP>−3</SUP> Torr) without an annealing step. The work function of graphene is reduced from 4.52 eV to 3.98 eV after doping. Multiple coatings of rPyB on graphene field-effect transistors (FETs) result in air stability for 90 days under ambient conditions. Selective n-type doping using a polydimethylsiloxane (PDMS) stamp and rPyB has also been performed on a large-area 16 × 16 graphene FET array. Our findings demonstrate a viable methodology for the cost-effective synthesis of an n-type dopant and its application in soft electronics.</P>

Effect of NaHCO₃ on the Productivity of a Microalga, Tetraselmis sp. MBEyh04Gc, in Floating Cube Photobioreactors

Yonghee CHO,Sang-min LEE,Dong-Woo SHIN,Sang-min LIM,Choul-Gyun LEE 한국생물공학회 2016 한국생물공학회 학술대회 Vol.2016 No.10

Development of Safety Culture Hazard Factors Analyzer in Nuclear Power Plants

( Yonghee Lee ),( Jun Woo Kim ),( Sangmun Shin ) 한국감성과학회 2014 춘계학술대회 Vol.2014 No.-

Safety culture has become an important topic in NPPs primarily during last two decades. The concept of safety culture in NPPs was introduced by the International Nuclear Safety Advisory Group (INSAG) in the post-accident meeting after the Chernobyl accident in 1986. It is difficult to analyze specific influences of all safety culture factors because of the dimensionality problems caused by a large number of input variables as well as application difficulties associated with analysis tools. Even though some safety culture assessment methods may have significant advantages, often these methods cannot provide enough evidence of causal relationships and the statistical inferences among a large number of input variables. Data mining has emerged as one of the key features for data computing and analysis to conduct a data analysis. To this end, an integrated approach called response surface data mining (RSDM) is proposed in order to overcome both dimensionality and analysis problems simultaneously. First of all, on/off line hazard factors of safety culture based on comparative studies among important safety culture reports from IAEA, INPO, and NRC are generated by using quality function deployment (QFD) analysis. Next, a new hazard factor index for safety culture is proposed including three types of characteristics (i.e., the smaller the better, the larger the better, and the nominal the best types).

Development of Safety Culture Hazard Factors Analyzer in Nuclear Power Plants

Yonghee Lee,Jun Woo Kim,Sangmun Shin 대한인간공학회 2014 대한인간공학회 학술대회논문집 Vol.2014 No.5

New Approach for Slope Deformation Measurement Using Terrestrial LiDAR in Nuclear Power Plant Site

( Yonghee Lee ),( Weon-hack Choi ),( Hak-sung Kim ),( Seok-chul Kim ) 대한지질공학회 2019 대한지질공학회 학술발표회논문집 Vol.2019 No.2

Recently, slope failures are frequently occurred in Korea due to localized torrential rainfalls induced by the world climate change. Therefore, the stability of slopes in nuclear power plant sites has become a major geotechnical issue in the nuclear industry. The slope monitoring using slope-mounted sensors (e.g., inclinometer, tension-wire, and precipitation gauge) are the most accurate and reliable motioning method for slopes. However, slope-mounted sensor systems are ineffective to evaluate the overall deformation of large slopes because measured data from the each slope-mounted sensor represent the single cross-area of the slope. In this study, terrestrial light detection and ranging system (LiDAR) was used to evaluate the overall slope deformation without slope-mounted sensor system. The testbed slope is located in ○○ nuclear power plant site. The length, height, and slope angle of the slope is 1,700 m, 80 m and 34°, respectively. The measurement and analysis procedure are as follows: (1) point cloud data acquisition using terrestrial LiDAR, (2) station adjustment using global navigation satellite system (GNSS), (3) noise filtering to remove unnecessary data (e.g., trees and transmission towers), and (4) slope digital elevation model (DEM) generation. The terrestrial LiDAR data that obtained in 2015 (53 scan positions) and in 2016 (91 scan positions) were compared in this study. There was no significant deformation on the testbed slope, however, slight sediment-scouring which has no impact on the slope stability was observed. Deformation analysis using terrestrial LiDAR data obtained periodically is cost-effective and reliable to monitor the overall deformation of the large slopes.