Automatic Building and Floor Classification using Two Consecutive Multi-layer Perceptron

Jaehoon Cha,Sanghyuk Lee,Kyeong Soo Kim 제어로봇시스템학회 2018 제어로봇시스템학회 국제학술대회 논문집 Vol.2018 No.10

Key issues of indoor localization is taking full advantages and overcoming its disadvantages. Indoor localization based on Wi-Fi fingerprinting attracts researchers’ attentions since it does not require new infrastructure and devices. Many devices such as smart phones and laptops, which have a function to capture Wi-Fi signals, can be used for Wi-Fi fingerprinting. However, due to unreliable Wi-Fi signals, there are still difficulty to achieve high positioning accuracy. The unreliable signal disturbs devices to find their locations. As a result, getting localization with devices sometimes makes a wrong decision in building classification. It is useless for people to find a destination floor if they are in different building. In this paper, we propose two consecutive multi-layer perceptrons to get more precise localization. With sumple structure, we get better performance and show precise decision results in building classification, which is critical in Wi-Fi fingerprinting. We use UJIndoorLoc dataset which is open dataset.

북핵 위기 20년

차재훈(Jaehoon Cha) 한국국제정치학회 2011 한국국제정치학회 기타간행물 Vol.2011 No.6

한-미 정부의 대북인식과 핵정책 상관성연구

차재훈(Cha, Jaehoon) 한국정치정보학회 2014 정치정보연구 Vol.17 No.2

북핵 해결과 관련한 지난 20년 동안의 미국과 한국의 강온 정책은 모두 실패해왔다. 북핵문제와 같이 단일한 협상문제를 20년 이상 지속적으로 끌고 오는 사례는 국제 분쟁 및 협상사례에서 쉽게 예를 찾지 못한다. 북핵문제는 어느 특정 국가의 일방적인 정책으로는 쉽게 해결할 수 없는 복잡한 구조를 가지고 변화하고 있지만 구체적 전략운용과 복합적 협력구조를 제대로 형성하지 못했기 때문이다. 북핵문제는 기본적으로 한미관계, 북미관계와 같은 양자협상과 6자회담과 같은 다자협상의 협상틀로 진행되어 왔다. 남북관계와 북미관계는 서로 상호적이고 북핵문제 해결은 한미동맹과 북한이라는 다자적 관점을 내포하고 있어서 문제해결이 쉽지 않다. 이러한 관점에 기반 해 본 연구에서는 북핵문제와 관련한 시대별 구조적 문제와 쟁점에 따른 한미 정부의 인식의 차이를 분석하고 효율적 대북핵정책 요건을 검토하고자 했다. It has been failed to reach the finalized political solution against North Korea’s nuclear issue by The United States and South Korea"s administration for nearly 20 years. This is a peculiar case that has never reached any solution among international negotiation cases. They failed to formulate a concrete strategy management and complex cooperative structure even though the nuclear issue around North Korea can never be solved by a one-sided approach. Nevertheless the attempts toward managing the nuclear issue around North Korea has basically proceeded only with the bilateral framework such as the Seoul-Washington alliance, the U.S-North Korea relations, and multilateral frameworks like the six-party nuclear talks. It has inevitably been related to multi or tripartite relations between the U.S., South Korea, and North Korea since the relationship between the U.S. and South Korea is interactive with the relationship between the U.S and North Korea. Through this point of view, this research will point out political and strategy problems and suggest a more detailed strategy management by exploring the perception gap of the U.S, and South Korea administrations and the correlations between this gap and actual policies regarding to the nuclear issue that have been made depending upon the then structural problems and issues.

대통령 국정 어젠다와 정책화 과정 평가

차재훈(Cha Jaehoon) 한국정치정보학회 2012 정치정보연구 Vol.15 No.1

This study aims at two major focus points of concern. First of all, it analyzes presidential agenda of four regimes from Kim Young-sam, Kim Dae-jung, Roh Moo-hyun to Lee, Myung Bak, and their policy-making processes in order to realize the agenda. It involves how to select presidential agenda, whether order of priority is considered to select agenda, and which elements and reasons are considered in selecting agenda. The second focus of study lies in exploring into the relation between policy decision process and legalization of agenda. These days, we go through some changes which all kinds of political issues and media reports propose a wide variety of challenging tasks in setting agenda. Studies on setting presidential agenda has evaluated that the president has had greater influences upon agenda of national assembly and the press. When the president gives organized concern to the pending issues and set policy priorities on them, the chances become higher that the presidential agenda would be realized with success. 본 연구는 두 가지 초점을 가지고 연구를 하고자 한다. 우선, 민주화 이후 김영삼-김대중-노무현-이명박 네 개 정권의 국정 어젠다와 이를 실현하기 위한 정책화 과정을 분석하고자 했다. 국정 어젠다를 어떻게 선택하는지 어젠다 선택의 우선 순위를 가지고 있는지 정책 어젠다를 선택하는 요소와 이유 등에 대해 살펴보고자 했다. 두 번째 연구 초점은 어젠다의 정책결정과정과 입법화 관계를 살펴보는데 있다. 어젠다 설정에서 언론보도와 각종 정치적 이슈는 과거 모델에 대해 다양한 도전적 과제를 제시하는 시대적 변화를 겪고 있다. 대통령의 어젠다 설정에 관한 연구를 볼 때 대통령은 언론과 의회의 어젠다에 더 큰 영향력을 행사하고 있다고 평가하고 있다. 현안에 대한 체계적인 관심이 기울여지고 대통령이 그 현안에 대해 정책 우선 순위를 두게 되면, 대통령의 국정 어젠다 형성과정에서 성공할 가능성이 커지게 된다.

A STUDY OF FAILURE MODE, EFFECTS AND CRITICALITY ANALYSIS PROCESS FOR THE RAILROAD SYSTEM

Jaehoon Kim,Hyun-yong Jeong,Dong-Wook Cha,Kwon-Shik Park,Jun-Seo Park 대한기계학회 2008 대한기계학회 춘추학술대회 Vol.2008 No.11

This study investigates the Failure Modes, Effects and Criticality Analysis (FMECA) Method for the railroad vehicle. Recently, RAMS (Reliability, Availability, Maintainability and Safety) is one of the most important issues in the railroad industry. FMECA is prerequisite for the RAMS Analysis, and it is a procedure to identify the potential failure modes and their effects and to reduce or mitigate the critical effects on the system. FMECA is used in various industries and it is specialized in each industry. For instance, MIL-1629a and SAE-J1739 are specialized FMECA method for Military industry and Automotive industry, respectively. Although the railroad industry requires the high reliability system, it does not have a specialized FMECA yet. Thus, in this paper, an FMECA method specialized to the railroad vehicle was proposed through analyses and comparison of the MIL-1629a, SAE-J1739 and IEC-60812 standards.

렌즈의 온도 구배를 고려한 결상광학계의 초점 열화 영향 분석

안재훈(Jaehoon Ahn),김은진(Eunjin Kim),차종환(Jonghwan Cha),복기소(Kiso Bok) 대한기계학회 2023 대한기계학회 춘추학술대회 Vol.2023 No.11

In order to address the issue of thermal drift, which causes the focus of the imaging optical system to blur due to temperature changes, an athermal design was conducted. In this process, the influence of temperature gradients distributed across each lens on changes in back focal length (△BFL) was analyzed. As an athermal design approach, the Imaging optical system was functionally divided into a projection system and an image system. The projection system used an optical passive athermalization method, while the image system utilized a mechanical passive athermalization method. Functionally, the projection and image systems were designed so that the movement direction of their respective focal lengths changed in opposite directions, and they were designed to move only a certain distance to ensure that the combined effect after temperature changes would cancel each other out. Additionally, finite element analysis results from multiple physics fields such as optics, optomechanics and cooling field were utilized for a more precise analysis. The proposed athermal design enables the core component, the projection lens, to act as a temperature compensator across the entire system, while reducing tolerance sensitivity, contributing to improvements in optical performance and competitive pricing.

고속도로 자율주행을 위한 Road Bank Estimation

장재훈(Jaehoon Jang),정한별(Hanbyul Chung),황준연(Junyeon Hwang),김명준(Myoungjune Kim),차항병(Hangbyung Cha) 한국자동차공학회 2011 한국자동차공학회 학술대회 및 전시회 Vol.2011 No.11

This research proposes vehicle state and road bank angle estimators for autonomous driving in highway. Road bank angle has a direct influence on vehicle dynamics and lateral acceleration measurement. However road bank angle is not directly measureable in current vehicle systems due to economical reasons, the major challenge is to differentiate the bias induced by road bank disturbances from actual vehicle lateral dynamic. This paper proposes a method of road bank estimation and provides the theoretical background for the vehicle lateral dynamics.

자긴가공된 SCM440 고강도강의 잔류응력평가에 관한 연구

김재훈(Jaehoon Kim),심우성(Woosung Shim),윤용근(Youngkwen Yoon),이영신(Youngshin Lee),차기업(Kiup Cha),홍석균(Suckkyun Hong) 한국추진공학회 2010 한국추진공학회지 Vol.14 No.4

Thick-walled cylinders, such as a cannon or nuclear reactor, are autofrettaged to induce advantageous residual stresses into pressure vessels and to increase operating pressure and the fatigue lifetimes. As the autofrettage level increases, the magnitude of compressive residual stress at the bore also increases. The purpose of the present paper is to predict the accurate residual stress of SCM440 high strength steel using the Kendall model which was adopted by ASME Code. Hydraulic pressure process was applied in the inner part and thick-walled cylinders were autofrettaged up to 30% overstrain levels. Electro polishing on the surface of autofrettage specimen was performed to get more accurate residual stress. Residual stresses were measured by X-ray diffraction method. The autofrettage surface which was plastically deformed analyzed using a scanning electron microscope(SEM). Although there were some differences in measured residual stress and numerical results, it has a tendency to agree comparatively with each other.

강인한 다리 구조 설계에 따른 사족 보행 로봇 제어 안정성 연구

강호선(Hosun Kang),안재훈(Jaehoon An),차현제(Hyeonje Cha),안욱진(Wookjin Ahn),송화영(Hwayoung Song),이인호(Inho Lee) 한국로봇학회(논문지) 2023 로봇학회 논문지 Vol.18 No.2

단일 및 복합실린더에서 자긴가공 해석에 관한 연구

심우성(Woosung Shin),김재훈(Jaehoon Kim),이영신(Youngshin Lee),차기업(Kiup Cha),홍석균(Sukkyun Hong) 한국추진공학회 2008 한국추진공학회지 Vol.12 No.4

In manufacturing aircraft, safety and lightness of structure are important factors. Utilizing autofrettage technique, these benefits can be obtained. This technique is most frequently applied to a single cylinder. However, the Bauschinger effect reduces the benefits of autofrettage process Therefore, there is increasing interest in the use of compound cylinder that combine shrink fit and autofrettage. In this paper, single and compound cylinders that has same geometry were considered. It was found that compound cylinder which was autofrettaged has lower tangential hoop stress and plastic strain than single cylinder at bore. This means a reduction in the impact of the Bauschinger effect after shrink-fitting which produces the beneficial bore hoop stress.