• 한국정보통신학회:학술대회논문집
• /
• 한국정보통신학회 2022년도 춘계학술대회
• /
• pp.86-88
• /
• 2022

LoRa 통신 프로토콜은 근 10년간 사물인터넷 네트워크를 위한 유망 기술로 평가받고 있다. 이론적으로, 처프 대역 확산 프로토콜을 사용하여 장거리 통신에 강인하고 하나의 물리 채널에 서로 직교하는 여러 논리채널을 제공할 수 있으며 중첩 성형의 망구조로 공간 다양성을 활용할 수 있는 것이 대표적 이유이다. 최근의 몇몇 연구들은 이러한 특징 중 논리 채널 사이의 불완전한 실질적인 준직교성을 지적한다. 그러나 직교하는 논리 채널을 형성하는 것은 확산 인자와 대역폭 두 가지 설정 인자임에도 불구하고 대부분의 연구는 확산 인자만을 요소로 직교성을 평가한다. 본 연구에서는 두 설정 인자를 모두 고려하여 논리 채널 사이의 준 직교성을 정리한다. 또한, 이에 따른 논리 채널 사이의 간섭으로 인해 변화하는 통신 품질을 정리한다.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 2004년도 학술대회 논문집 정보 및 제어부문
• /
• pp.30-32
• /
• 2004

With 3-D vision measuring, camera calibration is necessary to calculate parameters accurately. Camera calibration was developed widely in two categories. The first establishes reference points in space, and the second uses a grid type frame and statistical method. But, the former has difficulty to setup reference points and the latter has low accuracy. In this paper we present an algorithm for camera calibration using perspective ratio of the grid type frame with different line widths. It can easily estimate camera calibration parameters such as lens distortion, focal length, scale factor, pose, orientations, and distance. The advantage of this algorithm is that it can estimate the distance of the object. Also, the proposed camera calibration method is possible estimate distance in dynamic environment such as autonomous navigation. To validate proposed method, we set up the experiments with a frame on rotator at a distance of 1, 2, 3, 4[m] from camera and rotate the frame from -60 to 60 degrees. Both computer simulation and real data have been used to test the proposed method and very good results have been obtained. We have investigated the distance error affected by scale factor or different line widths and experimentally found an average scale factor that includes the least distance error with each image. The average scale factor tends to fluctuate with small variation and makes distance error decrease. Compared with classical methods that use stereo camera or two or three orthogonal planes, the proposed method is easy to use and flexible. It advances camera calibration one more step from static environments to real world such as autonomous land vehicle use.

• 한국의류학회지
• /
• 제20권2호
• /
• pp.282-297
• /
• 1996

The effective construction for ready-made clothes is one of the central concerns of both consumers and manufactuers in today's apparel industry. In order to reduce the burden of stocks and increase clothing fitness, systematic information on typical body sizes and somatotypes is essential. The purpose of this study i-: to provide basic data on young women's somatotypes for form designers and pattern makers. The subjects of the survey were 310 women of 18 to 26 years old. The study collected 84 anthropometric data for each Person. The data was analyzed by using of the multivariate method. The factor analysis was utilized in regard to the 65 items obtained from anthropometric measurement respectively. The principal component analysis was applied to the data with orthogonal rotation after extraction. The factor scores used in the factor analysis became the basis of determining the value of each variable of the cluster analysis. The cluster analysis was applied for identifying typical somatotypes. Ward's minimum variance method was applied for the purpose of extracting distance metrix by the standardized Euclidean distance. The element forming each cluster can be subdivided into several sets by crosstabulation which is obtained by the fastclus of the SAS. This research has demonstrated 3 distinctive types of silhouette contour of the trunk. Incidentally it also identified 4 of the lower body from the waistline to thigh contour respectively. The discriminant analysis showed that the most significant discriminant factor of the trunk classification were side neck point -1 scapular -1 waistiline length and waist girth. In Korea, the average somatotype of female college students tends to be tall, slim and straight. Reviewing the relationship between the classifications of three parts of body, they are related to each other to some extent but their distribution are not constant. Therefore, in view of clothing construction, a proper separation of the body surface is a necessity.

• 한국임상보건과학회지
• /
• 제6권2호
• /
• pp.1126-1135
• /
• 2018

Purpose. The purpose of this study is to investigate the success model related to the hospital information system accomplishment. It is important to examine the success model of the hospital information system and to analyze the factors affecting the job satisfaction accomplishment. Methods. The method of this study is to 150 copies of the entire survey data were distributed and 135 copies were collected, showing a collection rate of 90%. In order to ensure the reliability of the questionnaire items, Cronbach's Alpha was used to test reliability, and exploratory factor analysis was conducted to determine the convergence of various items. In order to grasp the convergence of various items, exploratory factor analysis was performed. The results of exploratory factor analysis were used to analyze the correlations between variables that were proven to have a single dimensionality before calculating factor loadings and regression analysis by Orthogonal Rotation by Varimax method Results. The results of this study, first, the system quality of the hospital information system has a statistically significant effect on user satisfaction. Second, the information quality of hospital information system is statistically significant for user satisfaction, indicating that information quality improves user satisfaction. Third, service quality of hospital information system was statistically significant in user satisfaction. Finally, the higher the satisfaction of the users who use the hospital information system, the higher the accomplishment of the organization Conclusions. This study is based on the successful model of D & M information system. In addition, the hospital information system, the user satisfaction, and the organizational accomplishment in connection with it can be found significant.

• Journal of Plant Biotechnology
• /
• 제2권3호
• /
• pp.157-163
• /
• 2000

Optimization of chemicals in the large scale sea water medium and inoculum for biomass and natural colourants production in the marine cyanobacteria, Phomidium tenue BDU 46241 (phycoerythrin producer) and P.valderianum BDU 30501 (phycocyanin producer) was carried out by experiments in L8 orthogonal array. Mathematical analysis revealed the significance of these factors. The factor(s) that critically control the yield varied with the organism and the end-product further, the desirable level of these factors between the normal and a higher level tested was identified and improved media were evolved. In both cyanobacteria, higher level of $K_2$$HPO_4$, $NaNO_3$ and inoculum with normal level of ferric ammonium citrate was found to be desirable for biomass production and additionally, higher level of $MgSO_4$ for pigment production. The level of other factors varied with the organism and the end-product. Confirmation experiments showed that the clues obtained based on mathematical experimentation are valid. In P.tenue, the medium optimized for biomass production increased the yield of biomass by 495% and the medium optimized for phycoerythrin production increased the yield of biomass by 408% with 30% increase in phycoerythrin content of the biomass. Similarly in P.valderianum, the medium optimized for biomass production increased the yield of biomass by 224% and the medium optimized for phycocyanin production increased the yield of biomass by 143% with 44% increase in phycocyanin content of the biomass.

• 한국항행학회논문지
• /
• 제12권4호
• /
• pp.332-340
• /
• 2008

본 논문에서는 OFDM (Orthogonal Frequency Division Multiplexing) 시스템의 주파수 효율 증가를 목적으로 시간 영역에 추가적인 데이터 신호를 중첩시키는 방법들의 성능을 비교한다. 본 저자들이 제안하였던 시간 영역 데이터 중첩 전송 (TDSD : Time Domain Superimposition of Data) 시스템은 기존 중첩 전송 방식들 (SPPT : the Superimposed periodic pilot in the time domain, APSB : the Added Pilot Semi-Blind channel estimation)이 파일롯 신호를 데이터와 중첩하도록 하는 방법과 달리 시간 영역에서 추가 데이터를 중첩시킨다. 그러나 중첩 전송 방식들은 데이터 전송률을 증가시킬 경우, 주파수간 간섭 (ICI)이 증가하는 관계를 갖는다. 하지만 TDSD는 선처리 과정을 통해서 시간 영역 신호와 주파수 영역 신호간의 간섭을 제거함으로써 주파수 효율을 증가시킬 수 있다. 본 논문에서 기존에 제안된 OFDM에서의 중첩 전송 방식들과 여러 모의실험을 통하여 성능을 비교한다. TDSD는 주파수 효율 측면에서 일반적인 OFDM 시스템과 비교할 경우 특정 중첩 전송 변수 사용 (M=16) 시 약 20%의 주파수 효율을 증가 시키는 데 반해 SPPT는 일반적인 OFDM과 비슷한 성능을 갖는다. 그리고 APSB는 비교 대상 중에서 가장 낮은 효율을 보인다.

• KSII Transactions on Internet and Information Systems (TIIS)
• /
• 제10권1호
• /
• pp.152-167
• /
• 2016

This paper investigates the simultaneous wireless information and power transfer (SWIPT) for two-hop orthogonal frequency division multiplexing (OFDM) decode-and-forward (DF) relay network, where a relay harvests energy from radio frequency signals transmitted by a source and then uses the harvested energy to assist information transmission from the source to its destination. The power splitting receiver is considered at the relay. To explore the performance limit of such a SWIPT-enabled system, a resource allocation (RA) optimization problem is formulated to maximize the achievable information rate of the system, where the power allocation, the subcarrier pairing and the power splitting factor are jointly optimized. As the problem is non-convex and there is no known solution method, we first decompose it into two separate subproblems and then design an efficient RA algorithm. Simulation results demonstrate that our proposed algorithm can achieve the maximum achievable rate of the system and also show that to achieve a better system performance, the relay node should be deployed near the source in the SWIPT-enabled two-hop OFDM DF relay system, which is very different from that in conventional non-SWIPT system where the relay should be deployed at the midpoint of the line between the source and the destination.

• Journal of Communications and Networks
• /
• 제11권1호
• /
• pp.26-35
• /
• 2009

In this paper, we investigate how to do resource allocation to guarantee a minimum user data rate at low signaling overhead in multi-cell orthogonal frequency division multiple access (OFDMA) wireless systems. We devise dynamic resource allocation (DRA) algorithms that can minimize the QoS violation ratio (i.e., the ratio of the number of users who fail to get the requested data rate to the total number of users in the overall network). We assume an OFDMA system that allows dynamic control of frequency reuse factor (FRF) of each sub-carrier. The proposed DRA algorithms determine the FRFs of the sub-carriers and allocate them to the users adaptively based on inter-cell interference and load distribution. In order to reduce the signaling overhead, we adopt a hierarchical resource allocation architecture which divides the resource allocation decision into the inter-cell coordinator (ICC) and the base station (BS) levels. We limit the information available at the ICC only to the load of each cell, that is, the total number of sub-carriers required for supporting the data rate requirement of all the users. We then present the DRA with limited coordination (DRA-LC) algorithm where the ICC performs load-adaptive inter-cell resource allocation with the limited information while the BS performs intra-cell resource allocation with full information about its own cell. For performance comparison, we design a centralized algorithm called DRA with full coordination (DRA-FC). Simulation results reveal that the DRA-LC algorithm can perform close to the DRA-FC algorithm at very low signaling overhead. In addition, it turns out to improve the QoS performance of the cell-boundary users, and achieve a better fairness among neighboring cells under non-uniform load distribution.

• 한국산림과학회지
• /
• 제99권6호
• /
• pp.891-899
• /
• 2010

이 연구의 목적은 선택실험기법을 활용한 조건부 로짓 모델을 이용하여 산림경관기능이 가지는 경제적 가치를 추정하는데 있다. 이를 위해 산림경관의 속성과 수준을 선정하였는데, 속성은 산림형태, 임상, 소밀도, 휴양적 요소, 지불의사금액 등이 그것이다. 이를 토대로 SAS 9.1을 이용하여 Orthogonal과 Balanced를 이루는 96개 선택 집합을 4개 타입으로 구성하였으며, 서울을 포함한 7개 광역시 시민을 모집단으로 설정하여 연간 가구당 지불할 의사를 면접조사방법으로 총 280부를 조사하였다. 그 결과, Non-ASC 모형에서 Mcfadden' ${\rho}$는 0.21, 우도통계량은 -2,631로 나타났다. 그리고 산림경관에 대한 가구당 평균 지불의사금액은 266,723원으로 나타났다.

• 한국소음진동공학회:학술대회논문집
• /
• 한국소음진동공학회 2005년도 추계 학술대회논문집(수송기계편)
• /
• pp.134-139
• /
• 2005

This paper presents a robust design of vehicle interior noise using Taguchi method and a substructure synthesis method with a hybrid model. Firstly, the proposed method identifies the critical process of the concerned interior noise through a TPA (Transfer Path Analysis). Secondly, a strategy for a robust design is discussed, in which the major noise factor among uncertainties in the process is quality distribution of rubber bushes connecting a cradle and a trimmed body. Thirdly, a virtual test model fer the process is developed by applying a substructure synthesis method with a hybrid modeling approach. Fourthly, virtual tests are carried out according to the predefined tables of orthogonal array in Taguchi robust design process. The process was performed under 2 sub-steps. The first step is sensitivity analysis of 31 panels, and the other step is weight optimization of mass dampers on sensitive panels. Finally, two vehicles with the proposed countermeasures were validated. The proposed method reduces 87.5% of trials of measurements due to the orthogonal arrays and increases robustness by 8.6dB of S/N ratio and decreases $5\;dB(A){\sim}10\;dB(A)$ of interior noise in the concerned range of RPM.