Droplet-based microfluidic single-cell isolation for screening chemical-producing bacteria screening with riboswitch-induced diverse fluorescent signaling level

byungjin LEE,Sungho JANG,Gyoo Yeol JUNG,Chang-Soo LEE 한국생물공학회 2017 한국생물공학회 학술대회 Vol.2017 No.4

Conjugated Polyelectrolyte-Based Fluorescent Surfactants: Synthesis and Emulsion Formation

Byungjin Koo(구병진) 한국고분자학회 2021 폴리머 Vol.45 No.4

양극성 계면을 형광을 통해 시각화하는 것은 계면에서 발생하는 여러 과학적 현상을 이해하는 데에 중요하다. 하지만 양극성 및 형광 특성을 동시에 보여주는 고분자의 종류는 매우 적으며, 그 주된 이유는 형광을 보이는 소수성 고분자 주사슬과 강한 친수성을 가지는 곁사슬을 동시에 합성하는 것이 까다롭기 때문이다. 공액 고분자 전해질 구조를 기반으로, 폴리페닐렌 에타이닐렌을 주사슬로 하는 새로운 양극성 형광 고분자를 합성하였다. 각각 아민과 알킬그룹을 가지는 두 단량체를 소노가시라 중합법을 통해 고분자를 합성하고, 1,3-프로판설톤과의 반응을 통해 아민그룹을 양쪽성이온(zwitterion)으로 만들어 강한 극성을 가지도록 하였다. 공계면활성제를 함께 이용하여 안정적인 오일-물 에멀젼을 형성하였다. 고분자의 형태를 광물리학을 이용해 분석한 결과, 용액, 침전, 박막과 비교하여 에멀젼에서는 고분자의 형태가 크게 평면화되고 따라서 π-π 상호작용이 커짐을 발견하였다. 이러한 결과는 향후 다양한 콜로이드 및 생물학에서 나타나는 양극성 계면의 시각화에 응용될 수 있을 것으로 기대된다. Visualization of the amphiphilic interface through fluorescence is of importance to understand the interfacial phenomena in a non-invasive way. However, there is a scarcity of surfactant conjugated polymers with strong fluorescence owing to the difficulty of synthetic procedures employing a hydrophobic polymer backbone with strongly hydrophilic side-chains. Herein, we report novel fluorescent polymeric surfactants based on conjugated polyelectrolytes (CPEs) containing zwitterionic and alkyl side-chains. A fluorescent poly(phenylene ethynylene) (PPE) backbone with amine and alkyl groups was synthesized by Sonogashira-type polymerization. The amines on PPE were treated with 1,3-propanesultone, resulting in the formation of zwitterionic groups. Stable oil-in-water emulsion was successfully formed with co-surfactants. The conformations of polymers in different physical states were compared through photophysical analysis. It was found that the PPE backbone was highly planarized at the oil-water interface with extended π-π interactions, providing potential applications in the non-invasive visualization of amphiphilic interfaces found in colloids and biology.

Demonstration of Addressable Organic Resistive Memory Utilizing a PC-Interface Memory Cell Tester

Byungjin Cho,Sunghoon Song,Yongsung Ji,Ho-Gil Choi,Heung Cho Ko,Jae-Suk Lee,Gun-Young Jung,Takhee Lee IEEE 2013 IEEE electron device letters Vol.34 No.1

<P>We demonstrated nonvolatile 8 × 8 array organic memory devices utilizing a PC-interface memory cell tester. The organic memory devices composed of a Ag/poly(3-hexylthiophene-2,5-diyl) (P3HT)/p<SUP>+</SUP> poly-Si structure exhibited excellent memory performance properties, including stable switching behavior, proper statistical distribution, and long retention time. We succeeded in independently addressing and reading the data in the memory cell array using the PC-interface memory cell tester, opening an avenue toward more realistic organic memory device applications.</P>

A Spatial-Domain Joint-Nulling Method of Self-Interference in Full-Duplex Relays

Byungjin Chun,Hyuncheol Park IEEE 2012 IEEE communications letters Vol.16 No.4

<P>In this letter, a spatial-domain joint-nulling method is proposed as a new means of suppressing the self-interference (or echo) occurring in full-duplex relays. Both amplify-and-forward (AF) and decode-and-forward (DF) type relays are considered. While the conventional method searches for the relay processing matrix from a discrete set of basis vectors obtained from the singular value decomposition (SVD) of the echo channel, the proposed method directly solves the optimal relay processing matrix over a continuous domain. As a result, it is shown that the proposed approach gives better performance than the conventional one in terms of the achievable rate.</P>

An Efficient Attitude Reference System Design Using Velocity Differential Vectors under Weak Acceleration Dynamics

Byungjin Lee,Sukchang Yun,Hyung-Keun Lee,Young Jae Lee,Sangkyung Sung 한국항공우주학회 2016 International Journal of Aeronautical and Space Sc Vol.17 No.2

This paper proposes a new method achieving computationally efficient attitude reference system for low cost strapdown sensors and microprocessor platform. The main idea in this method is to define and compare velocity differential vectors, geometrically computed from INS and GPS data with different update rate, for generating attitude error measurements which is further used for filter construction. A quaternion based Kalman filter configuration is applied for the attitude estimation with the adapted measurement model of differential vector comparison. Linearized model for Extended Kalman Filter and low pass filtered characteristics of measurement greatly extend the affordability of the proposed algorithm to the field of simple low cost embedded systems. For performance verification, experiment are done employing a practical low cost MEMS IMU and GPS receiver specification. Performance comparison with a high grade navigation system demonstrated good estimation result.

A Consulting Case of Rural Development Project in Korea

ByungJin Kwak,Kyung-Soo Noh,Ho-Kyun Shin KINFORMS 2011 Management Review Vol.6 No.2

With digital convergence era, spreading trends in terms of green management in the agricultural sector has rapidly developed with various fusion technologies. Consulting industry has not neglected to take actions into flow of rural development as alternative engines of green growth policy. Thus, this study intends to introduce a successful consulting case of rural development project in Korea. This study summarizes how the actual consulting project afferent to reduce the waste of time centered on the background, difficulties and key success concepts. Some contributions of this study are first the article is a good benchmarking practice for other local governments and NonGovernment Organizations. Second is to prove that the consulting practices are also applicable in the agricultural section as well. Third, the study improves the general prejudice with respect to rural development projects caused by aging tendency of farming population. In the future studies, more focus on the role of consulting firms and their continuous support would advance the literature.

Maximum Likelihood Estimation of Parameters from a Multivariate Normal Sample with 2-step Monotone Missing Pattern

Byungjin Choi 고려대학교 통계연구소 2004 應用統計 Vol.19 No.-

A sample with special missing pattern called a monotone sample or a monotone missing data pattern occurs in many applications. The statistical methods for analyzing a monotone sample have been developed by several analysts. The purpose of this paper is to introduce the maximum likelihood estimation of parameters when there is a multivariate normal sample with 2-step monotone pattern, and to present the maximum likelihood estimates of parameters in closed forms. These estimates can be obtained by maximizing the overall likelihood function which is expressed in terms of the marginal and conditional likelihood functions with respect to parameters. The maximum likelihood estimates presented are expected to he used to develop statistical methods for analyzing a multivariate normal sample with 2-step monotone pattern in applications.

Time-resolved microfluidic sample preparation for cryo-EM structural analysis of biomolecular assemblies

Byungjin LEE,Enchev Radoslav IVANOV,Sung Sik LEE,Matthias PETER,Chang-Soo LEE 한국생물공학회 2019 한국생물공학회 학술대회 Vol.2019 No.4

Antioxidant and Bioactive Films to Enhance Food Quality and Phytochemical Production during Ripening

Byungjin Min,Paul L. Dawson,Kalidas Shetty 한국축산식품학회 2005 한국축산식품학회지 Vol.25 No.1

Antioxidant films are one active packaging technology that can extend food shelf-life through preventing lipid oxidation, stabilizing color, maintaining sensory properties and delaying microbial growth in foods. Because raw, fresh and minimal processed foods are more perishable during storage or under display conditions than further processed foods, they rapidly lose their original quality. Foods are susceptible to physical, chemical, and biochemical hazards to which packaging films can be effective barriers. Although films incorporated natural (tocopherols, flavonoids and phenolic acids) or synthetic antioxidants (BHT, BHA, TBHQ, propyl gallate) have been extensively tested to improve quality and safety of various foods, food applications require addressing issues such as physical properties, chemical action, cost, and legal approval. Increased interest in natural antioxidants as substitutes for synthetic antioxidants has triggered research on use of the new natural antioxidants in films and coatings. Use of new components (phytochemicals) as film additives can improve food quality and human health. The biosynthesis of plant phenolics can potentially be optimized by active coatings on harvested fruits and vegetables. These coatings can trigger the plants natural proline-linked pentose phosphate pathway to increase the phenolic contents and maintain overall plant tissue quality. This alternate metabolic pathway has been proposed by Dr. K. Shetty and is supported by numerous studies. A new generation of active food films will not only preserve the food, but increase food's nutritional quality by optimizing raw food biochemical production of phytochemicals.

Thermal Properties and Lifetime Comparison of Various Ceramic-Package Light-Emitting Diodes

Byungjin Ma,Yungjun Ahn,김제민,최성순,Kwanhoon Lee 대한금속·재료학회 2013 ELECTRONIC MATERIALS LETTERS Vol.9 No.4

We developed two thermal structures with heat-conducting paths at the bottom side of low temperature cofired ceramic (LTCC) LED packages and compared their thermal properties and reliability. Using a computational fluidic dynamics (CFD) simulation, we were able to anticipate the improvement of the thermal properties. In addition, we experimentally confirmed the expected thermal properties using a method based on thermal transient responses. The measured thermal resistances of the small-via structure and the thermalslug structure were about 50% and 40% of the value of a normal structure with no via or slug, respectively. Lifetime tests of each LED package over 4,000 hours were carried out to compare the lifetimes of the LTCC LED packages and to investigate the relationships between the thermal properties and the lifetimes of the LTCC LED packages. We were able to estimate a lifetime of over 32,000 hours for the LTCC LED packages with thermal paths while the lifetime of the normal LTCC LED packages was estimated to be about 18,200hours. Also, we verified the strong relationship between the thermal property and the lifetime in LTCC LED packages.