건설신기술지정제도의 평가기준에 관한 연구

서용철,현창택 대한건축학회 1998 대한건축학회 학술발표대회 논문집 - 계획계/구조계 Vol.18 No.2

Building DSMs generation integrating Three Line Scanner (TLS) and LiDAR

서용철,Masafumi Nakagawa 대한원격탐사학회 2005 大韓遠隔探査學會誌 Vol.21 No.3

Aerodynamic losses for squealer tip with different winglets

서용철,이상우 대한기계학회 2019 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.33 No.2

Aerodynamic loss measurements and flow visualizations have been conducted for a squealer tip with different winglets. The present results for seven winglets indicate that winglet coverage along the pressure side has a negative effect in the loss reduction, whereas winglet coverage along the suction side has a positive effect. Winglet coverage along both sides performs better than that along the pressure side but worse than that along the suction side. The upstream half of the suction-side winglet plays a crucial role in the loss reduction. Thus, this portion needs to be included in the winglet for better aerodynamic performance. The pressure-side winglet brings additional flow disturbances similar to the ones existing over the plane tip back to the tip gap flow over the squealer tip. For the suction-side winglet, however, the tip gap flow is separated from the casing in a wide range between the leading edge and mid-chord.

Tip gap flow and aerodynamic loss generation in a turbine cascade equipped with suction-side winglets

서용철,이상우 대한기계학회 2013 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.27 No.3

The tip gap flow and aerodynamic loss generation over a plane tip equipped with a “constant-width suction-side” (CWSS) winglet and a “varying-width suction-side” (VWSS) winglet have been investigated in a turbine cascade. For a fixed tip gap of h/c = 2.0%, three different winglet widths of w/p = 5.28, 10.55, and 15.83% are tested for the CWSS winglet. The VWSS winglet is designed based on flow visualization and has almost the same winglet area as the CWSS winglet of w/p = 15.83%. In general, the suction-side winglets have a role to increase aerodynamic loss in the tip leakage vortex region but reduce aerodynamic loss in the passage vortex region. For the CWSS winglet, the total-pressure loss coefficient mass-averaged all over the measurement plane has no appreciable changes with increasing w/p from 0.0 to 10.55%, but tends to decrease with further increment of w/p. The VWSS winglet performs better in reducing aerodynamic loss in the passage vortex region than the CWSS winglet of w/p = 15.83% but leads to a little bit higher aerodynamic loss in the tip leakage vortex region. The aerodynamic loss reduction by the VWSS winglet is 7.4% in comparison with the plane tip without winglet, and is about 60% lower than that by the widest CWSS winglet.

지리정보시스템을 위한 고속 측지계 변환 모델 연구

서용철 한국지리정보학회 2004 한국지리정보학회지 Vol.7 No.3

본 연구에서는 실시간 측지계 변환 기법을 사용하는 지리정보시스템에 사용될 고속 변환 모델 개발을 수행하였다. 한 측지계에 준거하여 구축된 지리정보데이터를 다른 측지계에 준거하여 표시하는 경우 원 구축데이터의 좌표를 변환시키지 않고, 화면 표시나 출력 직전에 변환하여 표시하는 방법이 사용된다. 본 연구에서는 이러한 실시간 측지계 변환 작업의 속도를 향상시키고 높은 변환정확도를 유지하기 위한 방법으로, 지역 분할 변환 매개변수 계산에 의한 2차원 등각상사변환 모델의 적용 방안을 검토하였다. 연구 결과 일정한 범위 안에서는 비교적 많은 계산 시간을 필요로 하는 3차원 측지계 변환과 2차원 둥각싱사변환이 거의 동일한 변환 정확도를 나타내었으며, 영역분할에 의한 2차원 상사 변환 모델을 적용할 경우 높은 정확도를 유지하고 향상된 변환 속도를 나타내는 실시간 측지계 변환이 가능하다는 결과를 얻게 되었다. This research focuses on the development of a fast datum transformation model to be used in GIS that utilizes real-time data transformation. Instance, when a GIS data constructed according to a datum is conformed to another datum, instead of transforming the axes of the original data, the data is transformed right before the results are reflected on the monitor. In this research, the prospects of calculating transformation parameters for every grid cells on the area based on two-dimensional conformal transformation model in order to decrease real-time datum transformation time while maintaining a high accuracy has been investigated. Research results showed that for a fixed area, the accuracies of the two-dimensional conformal transformation and the three-dimensional datum transformation, which requires more computing time, were almost equal and fast transformation speed, high accuracy real-time datum transformation is made feasible by implementing the grid-divided two-dimensional conformal transformation model.

An Adjustment for a Regional Incongruity in Global Land Cover Map: case of Korea

서용철,박윤영,한경수,염종민 대한원격탐사학회 2006 大韓遠隔探査學會誌 Vol.22 No.3

Development of an INS Integrated Autonomous Positioning System for Assisting Effective Fire-fighting Activity

서용철 대한토목학회 2004 KSCE JOURNAL OF CIVIL ENGINEERING Vol.8 No.5

This paper describes the development of an INS (Inertial Navigation System) integrated autonomous positioning system, which can monitor and track the firefighter's position to assist a variety of fire-fighting activity and rescue services. By integrating an INS to the positioning system, it is also possible to obtain information of firefighter's position and physical state of posture (e.g. standing, collapsed or crouching), including velocity, without using external signal sources, since the INS consists of a highly accurate three-axis gyro sensor and a three-axis accelerometer. This complete system consists largely of three parts; the heart of the system, i.e., the INS integrated autonomous positioning system, a three - dimensional display system for displaying the firefighter's position and posture on a three - dimensional digital map, and a communication system using the laryngeal microphone to communicate with members outside the site of accident. Consequently, this research would obviously contribute to more efficient rescue activities as well as to the safety of the firefighters. Besides, we also summarize the overall system requirements and describe the architecture of hardware and software used in the prototype system in detail, and this paper presents results from field tests conducted at Tokyo University demonstrating its viability and utility.

단일 노드 인스턴스에서 키-값 저장소 기반 분산 NoSQL 데이터베이스 성능 비교

서용철(Yong-Cheol Seo),박성훈(Sung-Hoon Park),김영목(Yeong-Mok Kim),이재엽(Jae-Youp Lee),김윤(Yoon Kim) 한국디지털콘텐츠학회 2019 한국디지털콘텐츠학회논문지 Vol.20 No.11

With the recent proliferation of social networking and streaming services, the requirements for scalability and elasticity of distributed data repositories have become more important for developers in choosing a NoSQL database, an unstructured query language. Redis can cache database query results in memory through its caching system, reducing the number of database accesses. However, when there is a large amount of data that is not suitable for server memory, the Redis database has a limit on persistence and cannot guarantee safety. A new alternative to the memory-based Redis database is the disk-based Sorted Set DB (SSDB) database with Key-Value store. This paper evaluates and compares CRUD processing performance for Redis and SSDB using YCSB, a benchmark tool provided by Yahoo.

통합 GNSS 환경에서 도시공간 위성측위의 가용성 평가 시뮬레이션

서용철(Suh, Yong Cheol),이양원(Lee, Yang Won) 한국측량학회 2007 한국측량학회지 Vol.25 No.3

실내 환경에서의 3차원 공간데이터 취득을 위한 IMU, Laser Scanner, CCD 센서의 통합

서용철 ( Yong Cheol Suh ),장정정언 ( Masahiko Nagai ) 한국지리정보학회 2007 한국지리정보학회지 Vol.10 No.1

최근 들어 보행자 내비게이션을 위한 3차원 공간데이터의 요구가 급증하고 있다. 보행자 내비게이션에 있어서, 3차원 모델은 일반인의 시각에서 구체적으로 표현되어야 할 필요가 있다. 보행자 내비게이션을 위한 공간을 상세하게 구현하기 위해서는 실외 환경뿐만 아니라 지하쇼핑센터와 같은 실내 환경에서도 적용될 수 있는 3차원 모델을 개발하는 것이 필수적이다. 그러나 GPS 없이 모바일 맵핑만으로 3차원 데이터를 효율적으로 취득하기란 대단히 어렵다. 본 연구에서는 3차원 형상을 레이저 스캐너로 측정하고, 표면 텍스쳐는 CCD 센서로 취득하였으며, 계속적으로 변화하는 센서의 위치와 높이는 IMU를 통해 측정하였다. 또한 IMU의 위치데이터는 GPS의 위치보정 없이 CCD 이미지의 상대 표정을 통해 수정하였다. 연구결과로써, 디지털 카메라 및 레이저 스캐너와 IMU와의 통합을 통해 실내 환경에서 신뢰성 높고, 빠르며, 간편하게 3차원 공간 데이터를 취득할 수 있는 방법을 제안하였다. 3D data are in great demand for pedestrian navigation recently. For pedestrian navigation, we needs to reconstruct 3D model in detail from people`s eye. In order to present spatial features in detail for pedestrian navigation, it is indispensable to develop 3D model not only in outdoor environment but also in indoor environment such as underground shopping complex. However, it is very difficult to acquire 3D data efficiently by mobile mapping without GPS. In this research, 3D shape was acquired by Laser scanner, and texture by CCD(Charge Coupled Device) sensor. Continuous changes position and attitude of sensors were measured by IMU(Inertial Measurement Unit). Moreover, IMU was corrected by relative orientation of CCD images without GPS(Global Positioning System). In conclusion, Reliable, quick, and handy method for acquiring 3D data for indoor environment is proposed by a combination of a digital camera and a laser scanner with IMU.