• 한국세라믹학회지
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• 제47권4호
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• pp.308-311
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• 2010

Porous SiC samples were prepared with three types of wood (poplar, pine, big cone pine) by simply embedding the wood charcoal in a powder mixture of Si and $SiO_2$ at 1600 and $1700^{\circ}C$. The basic engineering properties such as density, porosity, pore size and distribution, and strength were characterized. The samples showed full conversion to mostly $\beta$-SiC with good retention of the cellular structure of the original wood. More rigid SiC struts were developed for $1700^{\circ}C$. They showed similar bulk density ($0.5{\sim}0.6\;g/cm^3$) and porosity (81~84%) irrespective of the type of wood. The poplar sample showed three pore sizes (1, 8, $60\;{\mu}m$) with a main size of $60\;{\mu}m$. The pine sample showed a single pore size ($20\;{\mu}m$). The big cone pine sample showed two pore sizes (10, $80\;{\mu}m$) with a main size of $10\;{\mu}m$. The bend strength was 2.5 MPa for poplar, 5.7 MPa for pine, 2.8 MPa for big cone pine, indicating higher strength with pine.

• 한국자동차공학회논문집
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• 제19권5호
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• pp.100-112
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• 2011

This paper studied on a theoretical approach to predict structural performances and weight -reduction rates of hybrid bodyshells in case that the material of underframe structure is substituted. To choose other light-weight materials to be substituted for the original underframe material, compressive, bending and twisting deformations are considered under constant stiffness and strength conditions, which derive some new weight-reduction indices from a structural performance point of view. Next, these weight-reduction indices were verified using the finite element analyses of some simplified examples. It is shown that the derived indices to estimate the weight-reduction can be utilized as a good criterion for material substitution of the underframe at a basic design stage.

• Current Research on Agriculture and Life Sciences
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• 제26권
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• pp.31-43
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• 2008

Introduction of construction cost estimating system is necessary to promote appropriate reflection of construction cost and simplified and efficient amount work. The results of this study are as follows. In the results of considering the basic concept and composition of a construction type estimating system, an example orders are concentrated on an apartment house in the country. The building appurtenant work of extension work is high(1.52) as compared with others. In regression analysis for a construction cost, the models are as follows. In a new construction work, (construction cost)=$12,004.8+4.09{\times}$(building area), and in extension work, (construction cost)=$-121.9+4.50{\times}$(building area). Accordingly, this study wishes to compare and analyzes main contents of original cost method and results cost method, and propose predetermined amount estimation device through existent literature study investigation for accumulation of the construction cost.

• Nuclear Engineering and Technology
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• 제51권6호
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• pp.1616-1625
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• 2019

Measuring occurrence times of random events, aimed to determine the statistical properties of the governing stochastic process, is a basic topic in science and engineering, and has been the subject of numerous mathematical modeling approaches. Often, true statistical properties deviate from measured properties due to the so called dead time phenomenon, where for a certain time period following detection, the detection system is not operational. Understanding the dead time effect is especially important in radiation measurements, often characterized by high count rates and a non-reducible detector dead time (originating in the physics of particle detection). The effect of dead time can be interpreted as a suitable rarefied sequence of the original time sequence. This paper provides a limit theorem for a high rate (diffusion-scale) counter with extendable (Type II) dead time, where the underlying counting process is a renewal process with finite second moment for the inter-event distribution. The results are very general, in the sense that they refer to a general inter arrival time and a random dead time with general distribution. Following the theoretical results, we will demonstrate the applicability of the results in three applications: serially connected components, multiplicity counting and measurements of aerosol spatial distribution.

• 대한화학회지
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• 제67권2호
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• pp.89-98
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• 2023

The cell membrane, also known as the biological membrane, surrounds every living cell. The main components of cell membranes are lipids and therefore called as lipid membranes. These membranes are mainly made up of a two-dimensional lipid bilayer along with integral and peripheral proteins. The complex nature of lipid membranes makes it difficult to study and hence artificial lipid membranes are prepared which mimic the original lipid membranes. These artificial lipid membranes are prepared from phospholipid vesicles (liposomes). The liposomes are formed when self-forming phospholipid bilayer comes in contact with water. Liposomes can be unilamellar or multilamellar vesicles which comprises of phospholipids that can be produced naturally or synthetically. The phospholipids are non-toxic, biodegradable and are readily produced on a large scale. These liposomes are mostly used in the drug delivery systems. This paper offers comprehensive literature with insights on developing basic understanding of lipid membranes from its structure, organization, and phase behavior to its potential use in biomedical applications. The progress in the field of artificial membrane models considering methods of preparation of liposomes for mimicking lipid membranes, interactions between the lipid membranes, and characterizing techniques such as UV-visible, FTIR, Calorimetry and X-ray diffraction are explained in a concise manner.

• 품질경영학회지
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• 제51권4호
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• pp.691-700
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• 2023

Purpose: This study aims to analyze the diffusion pattern of the Mongolian mobile phone market. In particular, we used a generalized diffusion model to explore the factors affecting market potenial. Methods: We used three diffusion models to estimate the number of mobile subscribers in Mongolia. Based on the Logistic model with the best fitness, we introduced time-varying market potential and explored the influence of various independent variables such as GDP and inflation. Results: Among the basic diffusion models, the Logistic model was the best in terms of estimation performance and statistical significance. The estimation results of the Generalized Logistic model confirm that investment in the telecommunication sector has a significant positive effect on market potential. The estimation of the Generalized Logistic model effectively describes the continuous growth of the Mongolian telecommunications market until recently. Conclusion: We have analyzed the diffusion pattern of the Mongolian telecommunications market and found that the amount of investment in the sector leads to the growth of the market size. This study is original in terms of its subject - Mongolian telecommunications market and methodology - time-varying market potential.

• 문화기술의 융합
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• 제10권5호
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• pp.673-679
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• 2024

최근 조선시대를 배경으로 한 여러 가지의 콘텐츠들이 등장하고 있지만, 한복의 기본 틀조차 지켜지지 않는 한복이 늘어나는 추세이다. 이에 본 연구에서는 문헌 고찰을 통해 한복의 기본적인 한복의 형태를 조사하고 본 게임 안에서의 DALL-E API를 활용하여 한복의 색상과 문양을 다양하게 표현하게 하는 시스템을 제작하고 게임에 구현하였다. 생성형 AI 서비스의 품질에 따라 결과가 일정하지 못하다는 단점과 전통한복 전문가의 고증을 통하지 못하였다는 한계가 있음에도 불구하고 본 연구의 결과는 전통 한복의 형태에 사용자의 창의력을 더해서 개인화하는 방법을 제안함으로써 조선시대 배경의 게임을 개발할 때 활용될 수 있는 기초 자료를 제시하였고, 게임을 통한 우리나라의 전통 한복의 아름다움과 가치를 전 세계로 알릴 필요성을 주장하였다는 의의가 있다. 향후 연구에서는 유저들의 선호도를 조사하여 인터페이스를 클릭하면 그에 맞는 이미지를 생성할 수 있는 시스템을 개발하고자 한다.

• 한국항행학회논문지
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• 제8권1호
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• pp.65-72
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• 2004

IEEE 802.11a 무선 LAN에서 사용하는 임의 접근 방식은 CSMA/CA(Carrier Sense Multiple Access/Collision Avoidance)에 기반한 DCF(Distributed Coordination Function)방식이다. 그러나, IEEE 802.11는 지수적 백오프 방식을 사용하기 때문에, 충돌이 일어났을 경우 경쟁 윈도우의 크기가 2배로 커진다. 따라서, 패킷 전송 지연 시간이 증가하게 되어, 효율성이 떨어진다. 본 논문에서는 제안된 수정된 백오프 알고리즘 방식을 사용하여 IEEE 802.11 MAC DCF 프로토콜의 TCP 패킷 전송 시간을 분석하였다. 결과로부터, OFDM/QPSK 변조 방식의 패킷 전송에 있어 패킷 전송 시간을 줄이기 위해서 TCP 패킷 크기가 증가해야 한다는 것을 알 수 있었고, 실험 결과로부터 TCP 계층 안 TCP 패킷 크기와 전체 메시지 전송 시간 상관관계에서 TCP 계층의 적당한 패킷 크기를 구할 수가 있었다.

• 한국인터넷방송통신학회논문지
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• 제23권2호
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• pp.103-111
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• 2023

본 논문은 시계열 데이터에 존재하는 이상값을 정상값으로 변환하는 새로운 데이터 보정기법을 제안한다. 최근 IT기술의 발전으로 센서를 통해 방대한 시계열 데이터가 수집되고 있다. 하지만 센서의 고장, 비정상적 환경으로 인해, 대부분의 시계열 데이터는 다수의 이상값을 포함할 수 있다. 이상값이 포함된 원천 데이터를 그대로 사용하여 예측모델을 구축하는 경우, 고신뢰도의 예측 서비스가 실현되기 어렵다. 이에 본 논문은 LSTM-GAN 모델을 활용하여 원천 시계열 데이터에 존재하는 이상값을 탐지하고, DTW(Dynamic Time Warping) 및 GAN 기법을 결합하여 분할된 윈도우 단위로 이상값을 정상값으로 보정하는 기법을 제안한다. 기본 아이디어는 탐지된 이상값이 포함된 윈도우에 인접한 정상 분포 데이터의 통계정보를 DTW에 적용하여 연쇄적으로 GAN 모델을 구축하여 정상적 시계열 데이터를 생성하는 것이다. 오픈 NAB 데이터를 활용한 실험을 통해, 우리는 제안 기법이 기존 2개의 보정기법보다 성능이 우수함을 보인다.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2005년도 ICCAS
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• pp.502-505
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• 2005

Researches about micro technology travel lively in these days. Such many researches are concentrated in the field of materials and a process field. But properties of micro materials should be known to give results of research developed into still more. In these various material properties, mechanical property such as tensile strength, elastic modulus, etc is the basic property. To measure mechanical properties in micro or nano scale, actuating must be very precise. PZT is a famous actuator which becomes a lot of use to measure very precise mechanical properties in micro research field. But PZT has a nonlinearity which is called as hysteresis. Not precision result is caused because of this hysteresis property in PZT actuator. Therefore feedback control method is used in many researches to prevent this hysteresis of PZT actuator. Feedback control method produce a good result in processing view, but cause a loss in a resolution view. In this paper, hysteresis is compensated by open loop control method. Hysteresis property is modeled in Mathematical function and compensated control input is constructed using inverse function of original data. Reliability of this control method can be confirmed by testing nickel thin film that is used in MEMS material broadly.