This is the research report concerned with the new stability concept and designing the controller of the time periodic systems. The periodic systems which is governed by time is very common in various type of dynamic systems. For example, the satellite is the large scale and the experimental test equipment as pendulum is also time periodic systems. The motion of the systems during the time interval is running repeatedly. While this periodic systems is running, the dynamic stability is important to behave the appropriate motion of the system's function. This research propose the new stability approach based on Lyapunov theorem which is analyzing the system's stability adapting the specific energy function. And also this research introduces the developing numerical procedures to retain the stability of time periodic system. Finally, the result of this research is very useful to judge the stability and design the controller of time periodic system.

목적 : 본 연구는 인공눈물과 습윤액에 대한 일반인의 올바른 사용법 인지 여부의 파악하고, 인공눈물 및 습윤 액 사용 시 시간 경과에 따라 눈물막 안정성(눈물띠 높이와 눈물막 파괴시간)에 미치는 영향을 측정하고자 하였다. 방법 : 첫 번째 실험은 온라인 설문조사로 안구점안액의 사용법에 대한 인지를 온라인 설문을 통하여 실시하였다. 두 번째 실험은 20명의 피실험자를 모집하여, OSDI 점수를 기준으로 건성안과 비건성안 그룹으로 나누고(건성안 그룹 10명, 비건성안 그룹 10명), 참가자에게 3개의 점안액(인공눈물(AT), 습윤액(CS), 식염수(SS)를 점안하도록 하였다. 점안 후 1분, 3분, 5분 단위로 눈물막 높이(TMH)와 눈물막 파괴 시간(TBUT)을 측정하여 눈물막 안 정성 변화를 확인하였다. 결과 : 127명의 온라인 설문 응답자 중 66.6%(N=82)가 인공눈물과 습윤액의 차이에 대해서 잘 모른다고 응답하였으며, 콘택트렌즈 착용자 중 68.1%(N=47)는 렌즈 착용 중 인공눈물을 점안한 경험이 있다고 답하였다. 점안 시 시간경과에 따라 눈물띠 높이는 통계적 유의성이 있었다.(Baseline<1 min and 3 min, p<0.050). 하지만 점안전과 5분경과시의 눈물띠의 차이는 없었다(p=0.720). 눈물막 파괴시간은 점안액 종류별로 유의적인 차이가 있었으며 (SS<AT, CS p<0.050) 시 간경과에 따른 유의적 차이도 있었다(baseline, 5 min after < 1 min after, p<0.050). 결론 : 많은 사람들이 올바른 사용법에 대한 인지가 부족하였으며, 올바른 사용법의 전달이 이루어져야 할 것 이다. 눈물띠 높이는 점안액에 따른 변화는 5분 이후에는 관찰되지 않았으며, 이는 일시적인 증상완화만을 의미할 수 있다. 눈물막 파괴시간은 인공눈물을 점안 시 1분경과시 가장 길게 나타났다. 식염수 점안 시 눈물막이 가장 불안정하게 되었으며, 특히나 눈물막 파괴시간에 미치는 영향이 가장 컸다.

In the present study, we investigate the effects of milling time and the addition of a process control agent (PCA) on the austenite stability of a nanocrystalline Fe-7%Mn alloy by XRD analysis and micrograph observation. Nanocrystalline Fe-7%Mn alloys samples are successfully fabricated by spark plasma sintering. The crystallite size of ball-milled powder and the volume fraction of austenite in the sintered sample are calculated using XRD analysis. Changes in the shape and structure of alloyed powder according to milling conditions are observed through FE-SEM. It is found that the crystallite size is reduced with increasing milling time and amount of PCA addition due to the variation in the balance between the cold-welding and fracturing processes. As a result, the austenite stability increased, resulting in an exceptionally high volume fraction of austenite retained at room temperature.

This paper focuses on the after synthesis of CdTe quantum dots(QDs) in aqueous solution. CdTe nanoparticles were prepared in aqueous solution using mercaptocarboxylic acid or thioglycolic acid(TGA) as stabilizing agents. QDs emit light smaller than the nano size. The contents of the mercaptocarboxylic acid, and a kind of raw material, were revealed for a period of time. We succeeded in synthesizing a very high quality QDs solution; we discussed how to make QDs better and to keep them stabilized. TGA is known as one of the best stabilizing agents. Many papers have mentioned that TGA is a good stabilizing agent. We dramatically confirmed the state of QDs after the experiments. The QDs solution can be influenced by several factors. Different content of TGA can influence the stability of the CdTe solution. Most papers deal with the synthesis of CdTe, so we decided to discuss the after synthesis process for the stability of the CdTe solution.

A study to analyze and solve problems of multi wire installation duct experiment has presented in this paper. We have taken Taguchi's parameter design approach, specifically orthogonal array, and determined the optimal levels of the selected variables through analysis of the experimental results using S/N ratio.

It has been widely recognized that accurate landslide susceptibility assessments are essential and effective to prevent disasters and minimize casualties as well as property damages. In recent decades, many slope stability assessment models have been developed and applied, including both steady and transient (time-variant) modeling approaches. None of them, however, solve well the relationship between rainfall and slope instability due to many simplifications in the boundary conditions and the flow in soil. As another slope stability modeling method, a new time-variant slope stability model is introduced in this study, the proposed model is then applied to 2011 Mt. Umyeon landslide event for model verification. The integrated surface and subsurface flow model is used to assess time-varying subsurface water amount governed by hydrological processes. In this flow model, a two-dimensional shallow water equation with diffusion wave approximation and a three-dimensional Richards’ equation are used to formulate the surface flow system and the saturated–unsaturated subsurface flow system, respectively. A widely used time-variant slope stability analysis model, TRIGRS, is also applied to the same event for comparison. The proposed model produced significantly improved results as compared with those of TRIGRS in terms of agreement with observation.

Methods for measuring or estimating of ground shape by a laser range finder and a vision sensor(exteroceptive sensors) have critical weakness in terms that these methods need prior database built to distinguish acquired data as unique surface condition for driving. Also, ground information by exteroceptive sensors does not reflect the deflection of ground surface caused by the movement of UGVs. Thereby, UGVs have some difficulties regarding to finding optimal driving conditions for maximum maneuverability. Therefore, this paper proposes a method of recognizing exact and precise ground shape using Inertial Measurement Unit(IMU) as a proprioceptive sensor. In this paper, firstly this method recognizes attitude of a robot in real-time using IMU and compensates attitude data of a robot with angle errors through analysis of vehicle dynamics. This method is verified by outdoor driving experiments of a real mobile robot.