Dynamic Multimodal Holograms of Conjugated Organogels via Dithering Mask Lithography

Jiseok Lee(이지석) 한국고분자학회 2021 한국고분자학회 학술대회 연구논문 초록집 Vol.46 No.1

Complex holographic systems can be dynamically controlled through exposure to external stimuli, yet they usually contain only a single type of holographic mode. Here, we report a conjugated organogel that reversibly displays three modes of holograms in a single architecture. Using dithering mask lithography, we realized two-dimensional patterns with varying cross-linking densities on a conjugated polydiacetylene. In protic solvents, the organogel contracts anisotropically to develop optical and structural heterogeneities along the third dimension, displaying holograms in the form of three-dimensional full parallax signals, both in fluorescence and bright-field microscopy imaging. In aprotic solvents, these heterogeneities diminish as organogels expand, recovering the two-dimensional periodicity to display a third hologram mode based on iridescent structural colours. Our study presents a next-generation hologram manufacturing method for multilevel encryption technologies.

Predicting Cultural Values in Islamic Countries: The Six Cultural Dimensions of Hofstede’s Model

Jiseok Lee(이지석),Hongyan Zhao(조홍연),Jihyun Heo(허지현),Cui Long(최룡),Jongwook Kwon(권종욱) 연세대학교 경영연구소 2020 연세경영연구 Vol.57 No.1

본 연구의 목적은 홉스테드의 문화 모형에 포함되지 않은 57개 이슬람 국가의 문화적 가치 점수를 추정하는 것이다. 홉스테드는 현재까지 수행된 문화가치관에 연구 중에서 가장 많이 인용되고 있으며 가장 포괄적인 연구 중 하나로 간주되고 있다. 초기에는 40개 국가를 대상으로 조사하였으나 현재 100개 이상의 국가의 가치관 점수를 발표하고 있다. 이렇게 포괄적인 연구임에도 불구하고 놀랍게도 소수의 이슬람 국가를 포함하고 있다. 따라서 본 연구는 57개 이슬람 국가를 대상으로 홉스테드 모형의 6가지 문화차원별 가치관 점수를 분석한 첫 번째 연구라 할 수 있다. 분석 결과, 이슬람 국가들은 모두 높은 집단주의 경향과 큰 권력거리 차원에 밀집해 있다는 것을 보여주었다. 불확실성 회피와 남성성 차원에 대해서는 이슬람 국가들은 대부분 중간 점수에 몰려있었다. 이 두 가지 문화차원에 대해서 대부분의 이슬람 국가들은 동질적인 문화를 가지고 있다는 의미이다. 이슬람 국가들은 대부분 절제되고 단기지향적인 경향을 보였다. 또한 흥미로운 점은 보통 이슬람 국가들은 동질적인 문화를 가지고 있다고 생각하지만 본 연구에서는 이슬람 국가들 간의 문화차이가 이슬람국가와 비이슬람국가 간의 문화차이보다 더 큰 것을 발견하였다. 이러한 연구결과는 이슬람 국가진출 다국적기업에게도 시사점을 제공한다. 이슬람 진출 다국적기업은 이슬람을 하나의 동질적인 문화로 간주하여 표준화 전략을 수립하기 보다는 문화에 적합한 차별화된 경영관행의 수립이 필요함을 보여주고 있다. 예를 들면 개인주의 문화차원에서 개인주의가 강한 문화에서는 개인의 성과를 강조하는 경영관행이 강조되어야 하지만 집단주의 성향이 강한 국가에서는 집단의 조화를 고려하는 관행의 설계가 필요하다. The aim of this paper is to estimate and analyse the cultural value scores of the 57 Islamic countries that were not included in Hofstede’s model. Hofstede conducted one of the most comprehensive studies about how values in the workplace are influenced by culture. His data covered more than 100 countries, and the study included the largest group of respondents of any cross-cultural value survey at the time. Given its popularity and the large number of countries encompassed, Hofstede’s model includes surprisingly few Islamic countries. To the best of our knowledge, the present study is the first to analyse the cultural value scores of the 57 Islamic countries. The results reveal that the Islamic countries are all densely clustered in the collectivist and large power distance dimensions. Regarding the uncertainty avoidance and masculinity dimensions, the Islamic countries mostly have medium scores and are intensively clustered. Islamic countries are mostly clustered in the restrained and short-term orientation dimensions. The finding that the cultural distance among Islamic countries is much greater than that between Islamic countries and non-Islamic countries is interesting. We also summarized some implications of the characteristics of the cultural values of Islamic countries. Multinational corporations must seriously consider adjusting their management practice approaches to align with Islamic culture to maximize performance.

Universal process-inert encoding architecture for polymer microparticles

Lee, Jiseok,Bisso, Paul W.,Srinivas, Rathi L.,Kim, Jae Jung,Swiston, Albert J.,Doyle, Patrick S. Nature Publishing Group, a division of Macmillan P 2014 NATURE MATERIALS Vol.13 No.5

Polymer microparticles with unique, decodable identities are versatile information carriers with a small footprint. Widespread incorporation into industrial processes, however, is limited by a trade-off between encoding density, scalability and decoding robustness in diverse physicochemical environments. Here, we report an encoding strategy that combines spatial patterning with rare-earth upconversion nanocrystals, single-wavelength near-infrared excitation and portable CCD (charge-coupled device)-based decoding to distinguish particles synthesized by means of flow lithography. This architecture exhibits large, exponentially scalable encoding capacities (>10<SUP>6</SUP> particles), an ultralow decoding false-alarm rate (<10<SUP>−9</SUP>), the ability to manipulate particles by applying magnetic fields, and pronounced insensitivity to both particle chemistry and harsh processing conditions. We demonstrate quantitative agreement between observed and predicted decoding for a range of practical applications with orthogonal requirements, including covert multiparticle barcoding of pharmaceutical packaging (refractive-index matching), multiplexed microRNA detection (biocompatibility) and embedded labelling of high-temperature-cast objects (temperature resistance).

Flow around a flexible plate in a free stream

JiSeok Lee,이상환 대한기계학회 2011 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.25 No.2

This paper presents a numerical scheme for fluid-structure interaction, especially for flexible structures. The lattice Boltzmann method with an immersed boundary technique using a direct forcing scheme is used for the fluid , and a finite element method with Euler beam elements is used for the flexible plate. The direct forcing scheme of the lattice Boltzmann method was improved for the immersed boundary scheme by introducing the occupation ratio of fluid lattices among the interpolated lattices. We compared the results of our proposed scheme with the known results of conventional schemes. Using the proposed numerical scheme, the flow around the flexible plate in a free stream is simulated for the effect of flexibility. Our results show that the major role of the flexibility of the flexible plate is the reduction of the resistance from flow. From the unsteady flow around a flexible plate, we found that the St of the flexible plate up to Re < 80 increased regardless of plate flexibility, but the St in the range of Re > 120 was dependent on plate flexibility. In the range of Re > 120 , the St of very flexible plate increased with increasing Re, while the St of rigid plate decreased with increasing Re .

Scalable Fabrication of Dynamic Holographic Polymer Microstructures for Multi-level Encryption Technologies

Jiseok Lee(이지석) 한국고분자학회 2022 한국고분자학회 학술대회 연구논문 초록집 Vol.47 No.2

<i>Shank3</i> -mutant mice lacking exon 9 show altered excitation/inhibition balance, enhanced rearing, and spatial memory deficit

Lee, Jiseok,Chung, Changuk,Ha, Seungmin,Lee, Dongmin,Kim, Do-Young,Kim, Hyun,Kim, Eunjoon Frontiers Media S.A. 2015 Frontiers in cellular neuroscience Vol.9 No.-

<P>Shank3 is a postsynaptic scaffolding protein implicated in synapse development and autism spectrum disorders. The <I>Shank3</I> gene is known to produce diverse splice variants whose functions have not been fully explored. In the present study, we generated mice lacking <I>Shank3</I> exon 9 (<I>Shank3</I><SUP>Δ<I>9</I></SUP> mice), and thus missing five out of 10 known Shank3 splice variants containing the N-terminal ankyrin repeat region, including the longest splice variant, Shank3a. Our X-gal staining results revealed that Shank3 proteins encoded by exon 9-containing splice variants are abundant in upper cortical layers, striatum, hippocampus, and thalamus, but not in the olfactory bulb or cerebellum, despite the significant Shank3 mRNA levels in these regions. The hippocampal CA1 region of <I>Shank3</I><SUP>Δ<I>9</I></SUP> mice exhibited reduced excitatory transmission at Schaffer collateral synapses and increased frequency of spontaneous inhibitory synaptic events in pyramidal neurons. In contrast, prelimbic layer 2/3 pyramidal neurons in the medial prefrontal cortex displayed decreased frequency of spontaneous inhibitory synaptic events, indicating alterations in the ratio of excitation/inhibition (E/I ratio) in the <I>Shank3</I><SUP>Δ<I>9</I></SUP> brain. These mice displayed a mild increase in rearing in a novel environment and mildly impaired spatial memory, but showed normal social interaction and repetitive behavior. These results suggest that ankyrin repeat-containing Shank3 splice variants are important for E/I balance, rearing behavior, and spatial memory.</P>

Prediction of Selective Formation of Chair- and Boat-Type Hydrogenated Graphene via Birch Reduction

Lee, Tae Kyung,Lee, Jiseok,Kwak, Sang Kyu American Chemical Society 2019 Chemistry of materials Vol.31 No.12

<P>Practical electronic device applications using graphene-based materials dictate that their band gap must be tunable. The synthesis of hydrogenated graphene has received much attention due to the desirable effect of the gap opening in the electronic band structure. In this study, we present the reaction mechanism of graphene hydrogenation, especially through Birch reduction, and its favorable hydrogenated conformations (chair- and boat-type) on Cu(111). The reduction of graphene was achieved by the graphene π-electron delocalization in the presence of a [Li(NH<SUB>3</SUB>)<SUB>4</SUB><SUP>+</SUP>·<SUP>-</SUP>@(NH<SUB>3</SUB>)<I><SUB>n</SUB></I>] ion-pair. Li<SUP>+</SUP> played an indispensable role in the graphene hydrogenation reaction by facilitating thermodynamically and kinetically favorable reactions when it interacts with the alcohol. For the hydrogenation of graphene on the Cu surface, unlike the freestanding condition, the formation energy revealed that the boat-type was thermodynamically more favorable, and the transfer of unpaired electrons of nonhydrogenated carbon atoms to Cu supports the same prediction. Our findings indicate that this boat-type hydrogenated graphene can be synthesized on Cu(111) through the mechanism of Birch reduction. Also, control of graphene band gaps is achieved by the selective formation of the chair- and boat-type conformations of graphene as self-sustained or on the substrate.</P> [FIG OMISSION]</BR>

Rapid Light-Driven Color Transition of Novel Photoresponsive Polydiacetylene Molecules

Lee, Jiseok,Seo, Sungbaek,Kim, Jinsang American Chemical Society 2018 ACS APPLIED MATERIALS & INTERFACES Vol.10 No.4

<P>We developed new photoresponsive polydiacetylene (PR-PDA) molecules by incorporating a photocleavable moiety, 6-nitropiperonyl alcohol (NP) or 4,5-dimethoxy-2-nitrobenzyl alcohol (DMN), into a self-assembling diacetylene molecule. Inducing steric disordering of the assembled PDA molecules by the cleavage of the photoresponsive moiety under 365 nm UV irradiation results in color transition from blue to red and development of red fluorescence, allowing convenient photo patterning. Further writing and erasing of fluorescence patterns are demonstrated toward novel secure information communication and anticounterfeiting applications.</P>

Temperature and field-dependent MFM measurements of MnAs/GaAs(001)

Jiseok Yang,Jiyoung Jang,Kyung Jae Lee,Sanghoon Lee,Kab-Jin Kim 한국자기학회 2020 한국자기학회 학술연구발표회 논문개요집 Vol.30 No.2

Observation of Current-Driven Bloch Line Motion

Jiseok Yang,Taekhyeon Lee,Kyoung-Woong Moon,Albert Min Gyu Park,Soogil Lee,Mincheol Shin,Sanghoon Kim,Kab-Jin Kim 한국자기학회 2023 한국자기학회 학술연구발표회 논문개요집 Vol.33 No.1