• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2005년도 추계학술대회 논문집
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• pp.272-274
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• 2005

A simple method for fabricating micro/nanoscale hierarchical structures is presented using a two-step temperature-directed capillary molding technique. This lithographic method involves a sequential application of molding process in which a uniform polymer-coated surface is molded with a patterned mold by means of capillary force above the glass transition temperature of the polymer. Using this approach, multiscale hierarchical structures for biomimetic functional surfaces can be fabricated with precise control over geometrical parameters and the wettability of a solid surface can be designed in a controllable manner.

• Current Optics and Photonics
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• 제5권2호
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• pp.155-163
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• 2021

We propose a novel optical encryption scheme for cipher-feedback-block (CFB) mode, capable of encrypting two-dimensional (2D) page data with the use of two-step phase-shifting digital interferometry utilizing orthogonal polarization, in which the CFB algorithm is modified into an optical method to enhance security. The encryption is performed in the Fourier domain to record interferograms on charge-coupled devices (CCD)s with 256 quantized gray levels. A page of plaintext is encrypted into digital interferograms of ciphertexts, which are transmitted over a digital information network and then can be decrypted by digital computation according to the given CFB algorithm. The encryption key used in the decryption procedure and the plaintext are reconstructed by dual phase-shifting interferometry, providing high security in the cryptosystem. Also, each plaintext is sequentially encrypted using different encryption keys. The random-phase mask attached to the plaintext provides resistance against possible attacks. The feasibility and reliability of the proposed CFB method are verified and analyzed with numerical simulations.

• International Journal of Computer Science & Network Security
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• 제21권12호
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• pp.21-28
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• 2021

In this paper, a novel data transferring method is introduced that can transmit sensor data without using data bandwidth or an extra-processing cycle in a delay insensitive network. The proposed method uses human devices as Mules, does not disturb the device owner for permission, and saves energy while transferring sensor data to the collection hub in a wireless sensor network. This paper uses IP addressing technique as the data transferring mechanism by embedding the sensor data with the IP address of a Mule. The collection hub uses the ARP sequence method to extract the embedded data from the IP address. The proposed method follows WiFi standard in its every step and ends when data collection is over. Every step of the proposed method is discussed in detail with the help of figures in the paper.

• ETRI Journal
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• 제41권3호
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• pp.298-307
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• 2019

This paper investigates the use of the inverse-free sparse Bayesian learning (SBL) approach for peak-to-average power ratio (PAPR) reduction in orthogonal frequency-division multiplexing (OFDM)-based multiuser massive multiple-input multiple-output (MIMO) systems. The Bayesian inference method employs a truncated Gaussian mixture prior for the sought-after low-PAPR signal. To learn the prior signal, associated hyperparameters and underlying statistical parameters, we use the variational expectation-maximization (EM) iterative algorithm. The matrix inversion involved in the expectation step (E-step) is averted by invoking a relaxed evidence lower bound (relaxed-ELBO). The resulting inverse-free SBL algorithm has a much lower complexity than the standard SBL algorithm. Numerical experiments confirm the substantial improvement over existing methods in terms of PAPR reduction for different MIMO configurations.

• Translational and Clinical Pharmacology
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• 제26권3호
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• pp.115-117
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• 2018

This tutorial explains the basic principles of mechanistic ligand-receptor interaction model, which is an operational model of agonism. A growing number of agonist drugs, especially immune oncology drugs, is currently being developed. In this tutorial, time-dependent ordinary differential equation for simple $E_{max}$ operational model of agonism was derived step by step. The differential equation could be applied in a pharmacodynamic modeling software, such as NONMEM, for use in non-steady state experiments, in which experimental data are generated while the interaction between ligand and receptor changes over time. Making the most of the non-steady state experimental data would simplify the experimental processes, and furthermore allow us to identify more detailed kinetics of a potential drug. The operational model of agonism could be useful to predict the optimal dose for agonistic drugs from in vitro and in vivo animal pharmacology experiments at the very early phase of drug development.

• ETRI Journal
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• 제44권4호
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• pp.695-707
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• 2022

As for the insufficient nature of the fossil fuel resources, the renewable energies as alternative fuels are imperative and highly heeded. To deliver the required electric power to the industrial and domestic consumers from DC renewable energy sources like fuel cell (FC), the power converter operates as an adjustable interface device. This paper suggests a new boost structure to provide the required voltage with wide range gain for FC power source. The proposed structure based on the boost converter and the quazi network, the so-called SBQN, can effectively enhance the FC functionality against its high operational sensitivity to experience low current ripple and also propagate voltage and current with low stress across its semiconductors. Furthermore, the switching power losses have been decreased to make this structure more durable. A full operational analysis of the proposed SBQN and its advantages over the conventional and famous structures has been compared and explained. Furthermore, a prototype of the single-phase converter has been constructed and tested in the laboratory.

• 한국수소및신에너지학회논문집
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• 제33권1호
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• pp.77-84
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• 2022

The experimental work has been carried out for the study of pyrolysis of oil samples used in industrial and utility boilers in Korea. For five oil samples, the characteristics of pyrolysis have been investigated with a thermogravimetric analyzer (TGA), and their kinetic parameters were obtained and compared each other. The rate order of pyrolysis rate for five oils were as follows: by-product fuel oil, pyrolysis oil, diesel, a heavy oil and refined oil. The pyrolysis of refined oil has been successfully described by the three step, first order reaction model while the single step reaction model has been used for other oils. For the reaction temperature over 550 K, the reactivity of refined oil was very poor compared with other oils.

• International Journal of Advanced Culture Technology
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• 제11권4호
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• pp.169-176
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• 2023

This study aims to assess the current status of career education at C University and to gather foundational data for developing a step-by-step career education curriculum and an integrated roadmap for curriculum and extracurricular career education. This research involves a comparative analysis of C University's enrolled students and external university students through a survey using the [University Career Exploration Model]. Data collection took place over one month in October 2023, and statistical analysis was conducted using the SPSS Statistics 25.0 program. The survey results enabled a comparative analysis of the career exploration processes and levels between enrolled students at C University and external university students. The proportion of enrolled students at C University responding positively to the career exploration process and level was high. Through this study, a better understanding of the career exploration processes and levels of university students was achieved. It is deemed necessary to conduct systematic research for continuous, tailored integration of curriculum and extracurricular career education at the university level.

• FOCUS: LIFE SCIENCE
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• 제1호
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• pp.9.1-9.5
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• 2024

Method development for complex low molecular mass (LMM) samples using reversed-phase (RP) separation conditions presents significant challenges due to the presence of many unknown analytes over wide concentration ranges. This guide aims to optimize method parameters-column length (L), temperature (T), flow rate (F), and final mobile phase conditions (Øfinal)-to maximize separation peak capacity. Validated by prior research, this protocol benefits laboratories dealing with metabolomics, natural products, and contaminant screening. This practical guide provides a structured approach to maximizing peak capacity for complex LMM separations. It complements computational optimization strategies and offers a step-by-step method development process. The Snyder-Dolan test is highlighted as essential for determining the need for gradient or isocratic elution and guiding column length decisions. The decision tree framework helps analysts prioritize variable optimization to develop effective separation methods for complex samples.

• 생물환경조절학회지
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• 제18권4호
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• pp.401-407
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• 2009

본 연구는 토마토의 도장 억제를 위하여 보다 안정적인 건묘를 생산하고자 육묘 기간 중 diniconazol 처리시기 처리농도에 따른 경엽처리와 침지 시간에 따른 종자처리가 묘 도장 억제에 미치는 영향을 알아보고 적정 방법을 구명하고자 수행하였다. Diniconazol 처리시기 및 처리농도에 따른 토마토의 초장 신장을 본 결과 1단계 2단계 3단계로 초장의 신장과 절간장 억제가 잘 나타났다. 이는 이른 시기가 늦은 시기보다 식물체가 받는 약제의 양이 더 많기 때문에 약제 효과가 잘 나타났다. 1단계는 4절, 2단계, 3단계는 각각 3절, 2절로 억제된 절간수가 줄어들었다. 약제 지속성이 초장의 신장에 미치는 영향을 본 결과 1단계, 2단계 $5mg{\cdot}L^{-1}$은 약제 처리 후 초장의 신장억제가 나타났으나 다른 처리구에 비해 일정한 시간이 지나면 빨리 회복하는 경향이 나타났다. 3단계에서는 초장 신장 억제 기간이 짧았고 빠른 회복을 보였다. 1단계는 5주, 2단계, 3단계는 각각 4주정도 약제 지속효과가 나타났다. 육묘 종료 후 정식한 결과 생체량이 빨리 증가 되어 생육에는 무처리와 유의차가 없었다.