<i>In Situ</i> Observation of Resistive Switching in an Asymmetric Graphene Oxide Bilayer Structure

Kim, Sungkyu,Jung, Hee Joon,Kim, Jong Chan,Lee, Kyung-Sun,Park, Sung Soo,Dravid, Vinayak P.,He, Kai,Jeong, Hu Young American Chemical Society 2018 ACS NANO Vol.12 No.7

<P>Graphene oxide decorated with oxygen functional groups is a promising candidate as an active layer in resistive switching devices due to its controllable physical-chemical properties, high flexibility, and transparency. However, the origin of conductive channels and their growth dynamics remain a major challenge. We use <I>in situ</I> transmission electron microscopy techniques to demonstrate that nanoscale graphene oxide sheets bonded with oxygen dynamically change their physical and chemical structures upon an applied electric field. Artificially engineered bilayer reduced graphene oxide films with asymmetric oxygen content exhibit nonvolatile write-once-read-many memory behaviors without experiencing the bubble destruction due to the efficient migration of oxygen ions. We clearly observe that a conductive graphitic channel with a conical shape evolves from the upper oxygen-rich region to the lower oxygen-poor region. These findings provide fundamental guidance for understanding the oxygen motions of oxygen-containing carbon materials for future carbon-based nanoelectronics.</P> [FIG OMISSION]</BR>

Analysis of Thermal Stress Effect on Blue Phosphorescent Organic Light-Emitting Diodes for Device Stability

Lee, Sungkyu,Lee, Ho Won,Na, Inyeob,Yoo, Han Kyu,Hwang, Kyo Min,Baek, Hyun Jung,Kim, Gyu-Tae,Kim, Young Kwan American Scientific Publishers 2017 Nanoscience and Nanotechnology Letters Vol.9 No.1

라이다를 활용한 온실에서 작물 및 작업자 인식

이성규 ( Sungkyu Lee ),이재수 ( Jaesu Lee ),김태현 ( Taehyun Kim ),백정현 ( Junghyun Baek ),임동혁 ( Donghyuk Lim ),김현종 ( Hyunjong Kim ) 한국농업기계학회 2021 한국농업기계학회 학술발표논문집 Vol.26 No.2

기후 및 농업환경 변화로 안정적인 수확을 할 수 있는 온실재배가 확대되고 있다. 온실내 환경을 제어하기 위한 스마트팜 기술로서 생육 및 자동화에 관한 여러 연구가 진행되고 있다. 라이다(lidar)는 현재 자율주행 및 맵제작에 활용되고 있으며 농업환경에도 과수원 등 노지에서 사용되고 있다. 본 연구는 라이다를 이용하여, 온실에서 작물의 생장을 확인하고 작업자의 이동을 파악하여 온실 내에서 정밀하고 안정적인 농작업 수행을 지원하는 것을 목표로 하였다. 온실의 환경 및 작업자를 인식하기 위해 라이다(VLP-16/PUCK, Velodyne, San jose, USA)를 사용하였으며, 이용한 온실은 단동형 비닐하우스로 크기는 길이 72m, 폭 6.6m, 높이 3m이다. 온실에는 고설 재배베드(높이 87cm)가 4줄로 설치되어 있으며, 재배베드 위에 화분(높이 18cm)이 놓여 있다. 바닥에는 선반 사이마다 트레이가 놓여 있으며 트레이 위에 작업대(높이 93cm)는 거리 이동이 가능하다. 작업대 위에 라이다를 고정하고, 약 0.5m/s 속도를 유지하면서 영상인식을 수행하였다. 트레이는 3줄이 설치되어 있으며, 실험은 왼쪽줄, 중앙줄, 오른쪽줄 순서로 진행하였다. 작물을 정식하기 전에 1차 실험, 정식 후 2차 실험, 정식 10일 뒤 3차 실험을 진행하였다. 작업자 인식 실험은 온실 내에서 라이다로부터 1m, 5m, 10m, 50m 위치에서 실험하였다. 또한 라이다에서 수직거리 5m, 10m에서 이동하는 작업자를 측정하였다. 실험을 통해 온실 내 작업환경을 3차원 인식할 수 있음을 확인하였고, 작물을 라이다를 통해 인식함으로써 작물 위치 및 생장을 확인할 수 있었다. 작업자 인식 실험의 경우는 이동하는 형체에 대해 확인할 수 있었으나 차폐가 발생하였을 경우 인식하지 못하는 한계가 있었다. 이상의 결과로 라이다를 이용하여 작물 생장 측정이나, 사람의 작업을 인식하여 인공지능 등에 활용이 가능할 것으로 판단된다.

병목 구조를 갖는 3D Convolutional Neural Network를 이용한 뇌파 기반 감정 인식

김성규(Sungkyu Kim),김태성(Tae-Seong Kim),이원희(Won Hee Lee) 한국정보과학회 2023 정보과학회 컴퓨팅의 실제 논문지 Vol.29 No.5

뇌파(EEG)는 두뇌를 구성하는 신경세포들의 전기적 활동을 두피에서 전극을 통해 비침습적으로 측정할 수 있는 전기신호로 실제 감정 상태를 객관적으로 반영하기 때문에 감정을 인식하는 중요한 도구로 사용되고 있다. 본 논문에서는 다중채널 뇌파 신호를 이용하여 시공간 및 공간스펙트럼 정보를 담은 3D 뇌파 데이터를 생성하였다. 분류 정확도의 손실 없이 연산 가속을 위해 병목 구조가 적용된 3D convolutional neural network 모델을 이용하여 3D로 재구성된 뇌파 데이터의 특징을 학습하여 valence와 arousal에 대한 감정을 분류하였다. DEAP 데이터셋을 이용하여 valence 및 arousal에 대한 이진 분류를 수행한 결과 시공간 데이터를 사용했을 때 각각 평균 98.22%와 98.85%, 공간스펙트럼 데이터를 사용했을 때 각각 평균 99.46%와 99.45%의 정확도를 달성하였다. Electroencephalography (EEG) is an electrical signal that can noninvasively measure the electrical activity of large, synchronously firing populations of neurons in the brain via electrodes on the scalp. EEG has been widely used as a tool to identify the emotional states of humans since it is capable of reflecting a real emotional state objectively. In this paper, we constructed 3D spatiotemporal and spatiospectral representations of EEG signals as the input of our proposed model. Using a novel 3D convolutional neural network with a bottleneck structure (CNN-BN), we assessed the classification accuracy of our CNN-BN model in the valence and arousal classification tasks. Using the DEAP dataset, our proposed model achieved average accuracies of 98.22% and 98.85% using 3D spatiotemporal representation as well as 99.46% and 99.45% using 3D spatiospectral representation for valence and arousal, respectively.

인버터의 스위칭 패턴 절환 기술에 의한 친환경자동차의 연비 및 NVH 개선 방법에 대한 연구

김성규(SungKyu Kim),곽무신(MuShin Kwak),이영국(YoungKook Lee),정진환(JinHwan Jung) 한국자동차공학회 2014 한국자동차공학회 학술대회 및 전시회 Vol.2014 No.11

차세대중형위성 4호 전자광학부체계 비행 모델의 열설계 및 해석 결과

이성규(SungKyu Lee),정용상(Yongsang Jung),주민욱(Minwook Joo),김경민(Kyoungmin Kim),김종운(Jongun Kim),정대준(Dae-Jun Jung),백명진(Myung-Jin Baek),공종필(Jong-Pil Kong),서석배(Seok-Bae Seo),이상규(Sang-Gyu Lee) 한국항공우주학회 2023 한국항공우주학회 학술발표회 논문집 Vol.2023 No.6

DRIVERS OF PERCEIVED LUXURIOUSNESS OF A PREMIUM PRIVATE LABEL PRODUCT

Seoyoung Kim,Sungkyu Lee,Jong-Ho Lee,Charles R. Taylor 글로벌지식마케팅경영학회 2016 Global Marketing Conference Vol.2016 No.7

Premium private label brands (PPLBs) are receiving increased attention in line with their significant growth. Private label brands (PLBs) have been evolving from offering low quality at a low price to high quality at a higher price. Among multiple tiers of PLB, PPLBs are assumed to be in an exclusive tier and compete with top-tier national brands. In consumers’ minds, PPLBs are perceived and evaluated in reference to alternatives represented by regular private label brands (RPLBs) and top-tier national brands (NBs). Thus, for PPLBs, being able to provide outstanding value that is perceived in relation with competitive alternatives is a critical issue. In addition, related marketing entities such as a store type are assumed to affect consumers’ perceptions and evaluations. Based on cue utilization theory and categorization theory, this research aims to identify key relationships influencing the perceived luxuriousness and eventual purchase intention of PPLB products. This research analyzes what strategies make consumers perceive a PPLB to be luxurious and in turn, increase purchase intention. The empirical study consists of a survey conducted among college students in their 20s in Korea. The data were analyzed to test the theoretical framework using a confirmatory factor analysis and structural equations.

ADVERTISING’S INFLUENCE ON PERCEIVED LUXURIOUSNESS OF A PREMIUM PRIVATE LABEL

Seoyoung Kim,Sungkyu Lee,Jong-Ho Lee,Charles R. Taylor 글로벌지식마케팅경영학회 2017 Global Fashion Management Conference Vol.2017 No.07

This study examines how advertising can be used by premium private labels to develop perceived luxuriousness and, in turn, purchase intention. The findings suggest perceived image and quality relative to regular private labels and a leading national brand as well as store-brand image congruity as key factors and support the store-type effect. Introduction Private labels (PLs) are receiving increased attention in line with their significant growth (Schnittka, 2015). Braak, Geyskens, and Dekimpe (2014) pointed out the evolving trend of more PLs offering high quality at a high price in comparison to their low-quality, low-price heritage. Among multiple tiers of PLs, PPLs exclusively aim at a premium tier of the market and try to offer the value comparable to that of top-tier NBs (Jost 2014). Acknowledging differentiated natures of PPLs, this paper analyzes what advertising strategies make consumers perceive a PPL to be luxurious and in turn, increase purchase intention. Cue utilization theory and categorization theory are used as a basis for hypotheses. Our research is an effort to shed light on adequate design of the advertising message for the successful introduction of a PPL. Theoretical Background Premium Private Label and Perceived Luxuriousness For a PPL, being able to offer outstanding value as compared to top-tier NBs is a critical issue (Geyskens, Gielens & Gijsbrechts 2010). To investigate whether a PPL is successfully positioned, we suggest the construct of perceived luxuriousness as a key variable. We define a brand's luxuriousness as its ability to satisfy multifaceted needs of consumers with its products which is not limited to functional needs (Lee, Ko, Kee & Kim, 2015), through five value dimensions (Vigneron & Johnson, 2004). Consequently, we employ the brand luxury index (BLI) to measure perceived luxuriousness (Vigneron & Johnson, 2004). Cue Utilization Theory According to cue utilization theory, when making purchases, consumers use diverse extrinsic and intrinsic cues, and make the assumption that such cues will help them make the most reasonable purchase decision (Richardson, Dick & Jain, 1994). Referring to cues, consumers decide to buy the product only if it is perceived as a better choice than the alternatives in terms of overall value that it conveys. These cues are often displayed and reinforced via advertising (Yi, 1993). Categorization Theory According to categorization theory, when exposed to advertising messages for a new brand, consumers are expected to call up information available in memory that is classified into categories (Carrillat, Harris, & Lafferty, 2010). Punj & Moon (2002) demonstrated that a successful strategy for new brands is to associate itself with a successful existing brand to be included in the consideration set while differentiating itself from other brands. Hypotheses Development Image Similarity Perceived similarity between brands and products has been discussed at various levels and scopes. It has been illustrated that shared physical attributes (Aaker & Keller, 1990) and shared abstract image (Park, Milberg & Lawson, 1991) between product lines moderate the probability of being perceived as similar by consumers. Considering the disparate positions between PPLs and RPLs, we suggested that RPLs are useful as a disparate option that may in turn emphasize the premium position of a PPL (Palmeira & Thomas, 2011). H1a. Image similarity between a PPL and a RPL, as reinforced by advertising, will have a negative effect on the perceived luxuriousness of the PPL. If a PPL can associate itself with the experiential value of a high-positioned NB, it is more likely that the PPL will be perceived as luxurious by signaling comparability (Sayman et al., 2002). H1b. Image similarity between a PPL and a NB, as reinforced by advertising, will have a positive effect on the perceived luxuriousness of the PPL. If the different positions of a RPL and a PPL are not perceived by consumers, consumers might judge the PPL as simply a similar but expensive option and would not be willing to purchase it (Huang & Huddleston, 2009). H2a. Image similarity between a PPL and a RPL, as reinforced by advertising, will have a negative effect on the purchase intention for the PPL. Closer associations between a PPL and a top-tier NB built through advertising lead to enhanced familiarity with the PPL and perceptions of reduced risks (Erdem, Zhao & Valenzuela, 2004). H2b. Image similarity between a PPL and a NB, as reinforced by advertising, will have a positive effect on the purchase intention for the PPL. Quality Superiority Perceived quality is defined by Aaker (1991) as: “the customer’s perception of the overall quality or superiority of a product or service with respect to its intended purpose, relative to alternatives”. Consumers’ abstract beliefs regarding the product’s quality can be deduced from “credence quality attributes” (Ophuis & Trijp, 1995). The quality of products is evaluated relatively, compared with alternatives. Nueno and Quelch, (1998) pointed out that there are a few characteristics shared by premium brands, and excellent quality is one of them. H3a. Quality superiority of a PPL compared to RPL, as reinforced by advertising, will have a positive effect on the perceived luxuriousness of PPL. H3b. Quality superiority of a PPL compared to NB, as reinforced by advertising, will have a positive effect on the perceived luxuriousness of PPL. According to Sethuraman, Tellis, and Briesch (2011), consumer perceptions of quality of a PL are evaluated based on quality differentials and play a dominant role when consumers make purchase decisions. Indeed, the perceived quality differential between a PL and a NB has been found to influence the share of the PL (Erdem et al., 2004). H4a. Quality superiority of a PPL compared to a RPL, as reinforced by advertising, will have a positive effect on the purchase intention of the PPL. H4b. Quality superiority of a PPL compared to a NB, as reinforced by advertising, will have a positive effect on the purchase intention of the PPL. Image Congruity between a Store and a PPL At the individual level, a generalized store image is determined by each consumer’s beliefs about retailer-specific attributes (Lee & Hyman, 2008). If the positive store image can be transferred through a number of positive associations between the store image and a PL, it will help consumers evaluate a newly encountered PL more favorably (Collins-Dodd & Lindley, 2003). As Dubois, Laurent, and Czellar (2001) demonstrated, consistent value shared between a parent brand and an extension will further strengthen the luxurious position. H5a. Image congruity between a store and a PPL will have a positive effect on the perceived luxuriousness of the PPL. Furthermore, with congruity consumers will see a brand which maintains the standards and preserve its essence as authentic and are likely to form positive responses toward a brand (Choi, Ko, Kim & Mattila, 2015). Lee and Hyman (2008) illustrated that the congruity between beliefs about a store and a PL would lead to a relatively favorable attitude toward a PL product. H5b. Image congruity between a store and a PPL will have a positive effect on the purchase intention of the PPL. Perceived Luxuriousness and Purchase Intention Sethuraman et al. (2011) illustrated that both quality and non-quality values matter in purchase decisions of a PL. For a PPL aiming at signaling an outstanding position, representations of added value are critical to form purchase intentions (Fionda & Moore, 2008). Thus: H6. Perceived luxuriousness of a PPL will have a positive effect on the purchase intention of the PPL. Store type Effect Consumers evaluate retailers differently and their subjective evaluation of the retailer is also expected to affect evaluations of products sold in the retailer (Grace and O’cass, 2005; Pappu and Quester 2008). The more upscale image and positioning of department stores are regarded to allow products they sell to be perceived as luxurious through more diverse appeals. In turn, purchase intentions are to be facilitated with ease, relatively. Proposition 1: According to store type, relative perception of luxuriousness of a PPL will be different. Proposition 2: According to store type, relative purchase intention of a PPL will be different. Methods Experiments were conducted among undergraduate-level students (aged 20-29) at a large Korean university, as they have relatively common traits and increasing experience with private labels (Trendmonitor, 2015). A total of 339 self-administered questionnaires were distributed, out of which 324 were used for analysis: 166 for department stores, 158 for hypermarkets. A purchase scenario of a cashmere sweater as well as an advertisement of the PPL sweater with information about each brand’s product (i.e. the material, the manufacturer, the distributor, and the advertisement) was given. For robust results, the experiment was conducted via two media types, online and paper. Analysis and Results Structural Model Testing We used structural equation modeling (AMOS 21) to test the proposed theoretical framework and propositions (see Figure 1). All estimates indicate an acceptable fit. Individual Hypothesis Testing The results indicate that image similarity between a PPL and a RPL negatively influences the perceived luxuriousness of the PPL (supporting H1a), but image similarity between the PPL and a NB positively influences the perceived luxuriousness of the PPL (supporting H1b). Although image similarity between a PPL and a RPL has no direct influence on the purchase intention of the PPL (H2a is rejected), image similarity between the PPL and a NB positively influences the perceived luxuriousness of the PPL (supporting H2b). Quality superiority of the PPL compared to the RPL positively influences both the perceived luxuriousness and purchase intention of the PPL (supporting both H3a and H4a), but quality superiority of the PPL compared to the NB does not have a significant effect (H3b and H4b are rejected). Congruity between the PPL and store is found to influence the perceived luxuriousness of the PPL (supporting H5a) but has no direct influence on the purchase intention (H5b is rejected). Meanwhile, the hypothesized effect of the perceived luxuriousness of PPL on purchase intention is supported (H6). Proposition Testing The data for each store type, department store (n =166) and hypermarket (n=158), was analyzed separately via multi-group analysis to assess store type effects on the modeled relationships. The findings for department stores indicate that the effects of image similarity between a PPL and a RPL on perceived luxuriousness, image similarity between the PPL and a NB on the purchase intention, quality superiority of the PPL compared to the RPL on the perceived luxuriousness as well as the purchase intention, and image congruity between the PPL and the store on the perceived luxuriousness are significant. Meanwhile, the findings for hypermarkets represent that the effects of image similarity between the PPL and NB on perceived luxuriousness and quality superiority of the PPL compared to the RPL on the perceived luxuriousness of the PPL are significant. For both store types, overall perceived luxuriousness turned out to be positively related to purchase intention. Conclusion The findings of this study have implications for a PPL aiming at positioning itself in consumers’ minds as luxurious, vis-?-vis a RPL and a NB. In regard to the perceived brand images, using advertising, efforts to differentiate a PPL from a RPL and to equate a PPL with the top-tier NB appears to be a reasonable strategy. Moreover, using advertising to emphasize superior quality compared to the RPL is likely to be effective whereas to compare it to a NB will not. Also, image congruity between a store and a PPL would allow the PPL to be perceived as luxurious as it aims to be. Furthermore, the results lead to a rationale for disparate strategies between two store types. As a follow-up study, we are planning to examine how direct manipulation of the comparative advertising messages influences consumers’ perceived luxuriousness and purchase intentions of a PPL.

Design of HTS power cable with fault current limiting function

Dongmin Kim,Sungkyu Kim,Jeonwook Cho,Seokho Kim 한국초전도저온학회 (구 한국초전도저온공학회) 2020 한국초전도저온공학회논문지 Vol.22 No.1

열전 모듈의 정전압 출력 시스템을 위한 벅-부스트 DC-DC 변환기

조성규(Sungkyu Cho),박순서(Soonseo Park),김지곤(Jigon Kim),남기훈(Kihun Nam),김시호(Shiho Kim) 대한전기학회 2010 전기학회논문지 Vol.59 No.10

We have proposed and fabricated a Buck-Boost DC to DC Converter for Thermoelectric generator (TEG) with constant output voltage suitable for battery chargers or constant voltage supplies in the range of several watt. The experimental and simulation results have shown that the proposed method allows stable operation with maximum 86% power transfer efficiency. The proposed circuit has a merit in cost and miniaturization of a system compared to conventional MPPT algorithms, because the proposed method adopts only analog circuit without DSP or micro controller unit for calculating peak power point by iterative methods.