• 한국세라믹학회지
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• 제35권12호
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• pp.1274-1279
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• 1998

The glass forming ability of the PbO-B2O3-TiO3-BaO system was investigated in relation to transitieon tem-peratures and the atomic ratio between constituents. Glass forming tendency was improved as the tem-peratures and the atomic ratio between constituents. Glass forming tendency was improved as the tem-perature differences between liquidus temperature and crystallization(or glass transition) temperature de-creased and the temperature difference between crystallization and glass transition temperature increases. The atomic ratio could be used as a criterion to deign glass systems. The interposition of B and Ba atoms between Pb and Ti atoms was one of important factors in glass formation.

• Bulletin of the Korean Chemical Society
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• 제33권3호
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• pp.980-986
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• 2012

In this paper we develop a minimalist model of single molecule spectroscopy in a dynamic environment. Our model is based upon a lattice system consisting of a probe molecule embedded in an Ising-model like environment. We assume that the probe molecule interacts with the Ising spins via a dipole-dipole potential, and calculate free energy curves and lineshapes of the system. To investigate fluctuation behavior of the system we exploit the metadynamics sampling method. In particular, using the method, we calculate the free energy curve of magnetization of the lattice and that of the transition energy of the probe molecule. Furthermore, we compare efficiencies of three different sampling methods used; unbiased, umbrella, and metadynamics sampling methods. Finally, we explore the lineshape behavior of the probe molecule as the system undergoes a phase transition from a sub-critical and to a super-critical temperature. We show that the transition energy of a probe molecule is broadly distributed due to the heterogeneous, local environments.

• 한국도로학회논문집
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• 제19권6호
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• pp.13-21
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• 2017

PURPOSES : In this research, an SB3-level roadside barrier for a highway transition zone that meets the newly established guide Installation and Management Guide for Roadside Safety Appurtenance is developed. Its performance is evaluated by a numerical simulation and real-scale vehicle impact test. METHODS : The commercial explicit dynamic software LS-DYNA is utilized for impact simulation. An FE model of a passenger vehicle developed and released by the National Crash Analysis Center (NCAC) at George Washington University and a heavy goods vehicle (HGV) model developed by the TC226/CM-E Work Group are utilized for impact simulation. The original vehicle models were modified to reflect the conditions of test vehicles. The impact positions of the passenger vehicle and truck to the transition guardrail were set as 1/2 and 3/4 of the transition region, respectively, according to the guide. RESULTS : Based on the numerical simulation results of the existing transition barrier, a new structural system with improved performance was suggested. According to the result of a numerical simulation of the suggested structural system, two sets of transition barriers were manufactured and installed for real-scale vehicle impact tests. The tests were performed at a test field for roadside safety hardware of the Korea Highway Corporation Research Institute. CONCLUSIONS : The results of both the real-vehicle impact tests and numerical simulations of the developed transition barrier satisfied the performance criteria, and the results of numerical simulation showed good correlation with the test results.

• 한국경제지리학회지
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• 제16권4호
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• pp.647-669
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• 2013

화석연료의 고갈과 국제 유가의 폭등, 기후온난화와 빈번한 환경 재난은 자원 및 환경 담론과 정책의 강화를 요청했으며, 이에 따라 지속가능한 발전의 개념이나 탄소 규제 전략에 바탕을 둔 정책들이 추진되어 왔다. 그러나 이러한 기존 개념이나 전략들은 신자유주의화 과정에 포섭되면서, 실효성이 있는 성과를 얻지 못했다. 이러한 점에서 새로운 전략적 규범적 개념으로 에너지 전환과 더불어 에너지 자립의 개념이 제시된다. 대구시는 비교적 일찍 에너지 문제에 관심을 가지고 솔라시티 정책을 추진해 왔지만, 거시적 배경에 편승하여 도시 에너지 문제를 제대로 대응하지 못했다. 이러한 점에서 이 논문은 대구시의 에너지 문제 실태와 정책의 의의와 한계를 살펴보고, 도시 에너지 전환과 자립을 위한 4가지 원칙, 즉 화석에너지 및 핵에너지에서 재생가능 에너지로의 전환, 공급주도형에서 수요관리 중심 정책으로의 전환, 중앙집중형에서 지역분산형 에너지 시스템으로의 전환, 그리고 시장의존적 관리에서 시민 참여적 에너지 거버넌스로의 전환 등을 제안하면서 이에 바탕을 둔 구체적 방안들을 제시하고 있다.

• Macromolecular Research
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• 제16권8호
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• pp.670-675
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• 2008

A series of pH and temperature-responsive (N,N-diethylacrylamide-co-methylacrylic acid) copolymers were synthesized by radical copolymerization and characterized by elemental analysis, Fourier-transform infrared (FT-IR), nuclear magnetic resonance (NMR) $^1H$, $^{13}C$ and LLS. The effects of salt and pH on the phase transition behaviors of the copolymers were investigated by uv. With increasing NaCl concentration, significant salt effects on their phase transition behaviors were observed. UV spectroscopic studies showed that the phase transition became faster with increasing NaCl concentration. In addition, the phase transition behaviors of copolymers were sensitive to pH. The pH and temperature sensitivity of these copolymers would make an interesting drug delivery system.

• 한국초전도ㆍ저온공학회논문지
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• 제21권3호
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• pp.6-12
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• 2019

Extended Drude model has been used to obtain information of correlations from measured optical spectra of strongly correlated electron systems. The optical self-energy can be defined by the extended Drude model formalism. One can extract the optical self-energy and the electron-boson spectral density function from measured reflectance spectra using a well-developed usual process, which is consistent with several steps including the extended Drude model and generalized Allen's formulas. Here we used a reverse process of the usual process to investigate the extended Drude analysis when an additional low-energy interband transition is included. We considered two typical electron-boson spectral density model functions for two different (normal and d-wave superconducting) material states. Our results show that the low-energy interband transition might give significant effects on the electron-boson spectral density function obtained using the usual process. However, we expect that the low-energy interband transition can be removed from measured spectra in a proper way if the transition is well-defined or well-known.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1993년도 한국자동제어학술회의논문집(국제학술편); Seoul National University, Seoul; 20-22 Oct. 1993
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• pp.18-23
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• 1993

In this paper, we attempt to estimate the state of a finite state system. In such system, we can observe time series data which has some significant behaviors corresponding to its system states. The behavior is characterized by feature parameters extracted from time series. Our thought is that the system output time series data is expressed as a sequence of behavior patterns which are represented by clusters in feature parameters space. An algorithm jointing fuzzy clustering to fuzzy finite state transition model is suggested.

• 제어로봇시스템학회논문지
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• 제14권3호
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• pp.248-253
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• 2008

This paper presents a sensing system for smart home which can detect an location transition events such as entrance/exit of a member and identify the user in a group at the same time. The proposed system is compose of two sub-systems; a wireless sensor network system and a database server system. The wireless sensing system is designed as a star network where each of sensing modules with ultrasonic sensors and a Bluetooth RF module connect to a central receiver called Bluetooth access point. We propose a method to discriminate a user by measuring the height of the user. The differences in the height of users is a key feature for discrimination. At the same time, the each sensing module can recognize whether the user goes into or out a room by using two ultrasonic sensors. The server subsystem is a sort of data logging system which read the detected event from the access point and then write it into a database system. The database system could provide the location transition information to wide range of context-aware applications for smart home easily and conveniently. We evaluate the developed method with experiments for three subjects in a family with the installation of the developed system into a real house.

• 한국인터넷방송통신학회논문지
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• 제17권6호
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• pp.27-31
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• 2017

본 논문에서는 낮은 삽입 손실을 가지는 광대역 DSPSL (double-sided parallel-stripline) - CPS (coplanar stripline) 전이구조를 제안하였다. 제안하는 전이구조는 자연스러운 전계분포의 필드 변환과 DSPSL과 CPS 사이의 임피던스 정합의 관점에서 설계되었다. 전이구조의 명확한 설계방법을 제시하여 바닥면 그라운드의 변화와 전이구조의 길이를 결정할 수 있게 하였다. 설계의 제작된 전이구조의 특성은 전이구조 당 6.2 ~ 18.2 GHz의 대역에서 0.7 dB의 낮은 삽입 손실을 가지고 있으며, 6.2 ~ 30 GHz 이상의 대역에서 1.25 dB의 삽입 손실을 가짐을 확인하였다.

• 전력전자학회논문지
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• 제27권4호
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• pp.356-366
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• 2022

This paper presents a mode transition method that applies frequency compensation technique of an LLC resonant converter for stable mode transition. LLC resonant converters used in various applications require high efficiency and high power density. However, because of circuit property, a wider voltage gain range equates to a greater circuit loss, so maintaining high efficiency at all voltage gain ranges is difficult. In this case, full bridge-half bridge mode transition method can be used, which maintains high efficiency even in a wide voltage gain range. However, this method causes damage to the circuit through overcurrent by the mode transition. This study analyzes the cause of the problem and proposes a mode transition method that applies frequency compensation technique to solve the problem. The proposed method verifies the stable transition through simulation analysis and experimental results.