• Journal of the Korean Institute of Telematics and Electronics B
• /
• v.33B no.3
• /
• pp.38-46
• /
• 1996

In this paper, a multi-velocity log system which uses ultrasonic pulsed doppler signal is developed. The output of the system is the absoluted velcocity of the ship. By using digitral signal processing, we get the vector velocity which displays the ship's speed about fore, aft, port and starboard. And this system give us the information about depth. This multi-velocity system has a large merit that is bottom and water track velocity. In addition, this has the high accuracy and can measure the water-depth according to the deep mode. And the fish finder, echo sounder or docking system will be made by applying the speed log system.

• Journal of the Korean Society of Costume
• /
• v.48
• /
• pp.83-100
• /
• 1999

Articles from leading daily newspapers dealing with costumes analyzed here dating back to oughly one year before the I.M.F. system came into place in korea. The values and esthetic consciousness of that period were studied through fashion. The major conclusions of the study are as follows: 1. The values of exhibition conformity and extravagance were emphasized. 2. The beauty of play the beauty of the extraordinary and the beauty of splendour were expressed as the esthetic consciousness 3. Preference of young people toward expensive high-grade and foreign-made brands was excessive Adults have to guide the young not to overconsume. Development of a sounder culture of clothing is needed for the establishment of economic prosperity for the nation.

• Journal of Korean Port Research
• /
• v.14 no.1
• /
• pp.47-55
• /
• 2000

In order to cope with the changes of container terminal situation in these days, many simulation studies for container terminal have been accomplished. But previous simulation studies using simulation language have limitations in model representation and difficulties in modeling of large scaled container terminal system. To make these problems better, this paper addresses an object-oriented simulation of container terminal system using a DEVS formalism. The DEVS(Discrete Event System Specification) formalism, developed by Zeigler, supports specification of discrete event system in a hierarchical and modular manner. The formalism provides a mathematical basis for studying discrete event systems with better understood and sounder semantics. In a step of system modeling, a DEVS formalism aims at the exact system modeling that has a basis of semantics and utilizing the object-oriented manner can flexibly cope with the changes of system environment. In this study a model is developed and verified through the simulation of some alternatives.

• Korean Journal of Fisheries and Aquatic Sciences
• /
• v.50 no.5
• /
• pp.605-615
• /
• 2017

A multi-resonant broadband acoustic transducer with six Tonpilz elements operating at different resonant frequencies in a transducer assembly was fabricated, tested, and analyzed. A compensated transducer, modified by adding series inductance to the developed multi-resonant broadband transducer, was shown to provide improved bandwidth performance with a relatively more uniform frequency response compared with the uncompensated transducer. By controlling the series inductance, flat frequency response characteristics at two frequency bands were obtained over the range 38-52 kHz with 1.1 mH inductance and 50-60 kHz with 0.4 mH inductance. These results suggest that the operating frequency of the developed multi-resonant broadband transducer in a chirp echo sounder can be shifted to a different frequency band that is optimized according to the environment for more effective echo surveys of fishing grounds.

• Journal of the Korean Institute of Navigation
• /
• v.3 no.2
• /
• pp.21-30
• /
• 1979

Echo sounder and Doppler sonar are to theultra-sonic transducers for measuring the depth and the ship's speed respectively. To measure the depth and speed with a single transducer, it is required to control the ultra-sonic beam to optional direction. In the past, the direction of the transducer itself is varied, but such a method provoked much problems in the mechanical design of the equipment. This paper deals with the method to control beam direciton by the phase control of the plural arrangement of transducers, and the results are studied by a computer simulation. The remarkable results of the study is condensed as follows; 1. The greater the interval of arrangement between transducers, the sharper the radiation pattern is, but in this case, the level of undesired sidelobe is also increased. 2. The control of radiation pattern up to 60 degree can be achieved by an adequate arrangement of more than 10 transducers. 3. It is shown that a simultaneous measurement of both depth and speed can be achieved by alternating directivity of the pulse by the method proposed in this paper.

• Journal of Institute of Control, Robotics and Systems
• /
• v.19 no.9
• /
• pp.774-781
• /
• 2013

The purpose of this paper is to design a DVL-RPM based VKF (Velocity Kalman Filter) design for a performance improvement underwater integrated navigation system. The proposed approach relies on a VKF, augmented by a altitude from Echo-sounder based switching architecture to yield robust performance, even when DVL (Doppler Velocity Log) exceeds the measurement range and the measured value is unable to be valid. The proposed approach relies on two parts: 1) Indirect feedback navigation Kalman filter design, 2) VKF design. To evaluate proposed method, we compare the results of the VKF aided navigation system with simulation result from a PINS (Pure Inertial Navigation System) and conventional INS-DVL method. Simulations illustrate the effectiveness of the underwater navigation system assisted by the additional DVL-RPM based VKF in underwater environment.

• Proceedings of the Korean Association of Geographic Inforamtion Studies Conference
• /
• 2003.04a
• /
• pp.300-304
• /
• 2003

기상위성은 그 특성상 다양한 Imager, Sounder, 그리고 여러 환경 테스트용 장비를 지니게 되며 일정한 시간동안 지구에 그 정보를 전송한다. 본 논문에서 제안된 수신 시스템은 현재 운영중인 아리랑위성 1호의 임무계획에 필요한 기상정보를 직접 획득하여 운영의 효율성을 높일 필요성에 의해서 GMS-5의 S-VISSR data 뿐만 아니라 2003년 4월 이후에 서비스를 할 것으로 예정된 GOES-9위성의 GVAR data도 역시 수신 및 처리를 할 수 있도록 설계되었다. Link budget 설계를 수행하여 최악의 경우에도 영상을 복원할 수 있는 통신링크가 제공되도록 설계하였고, 시스템 구성 모듈을 가능한 한 상용제품으로 사용하였다. 설치된 후에는 태양을 이용한 G/T의 값을 측정하여 설계치 보다 약1.608 향상된 시스템임을 검증하였고, 수신된 GMS-5의 S-VISSR 데이터를 성공적으로 처리함으로써 자체적으로 개발한 처리 소프트웨어를 검증하였다.

• 한국지구물리탐사학회:학술대회논문집
• /
• 2003.11a
• /
• pp.370-378
• /
• 2003

Continuous seismic refraction, reflection and echo-sounder surveys conducted at Koyna Project site provided geotechnical information which helped in choosing the alignment for Head race tunnel and in designing and choosing the site for Lake Tap. Seismic refraction survey both on land and in shallow water determined depths to bedrock and helped in inferring the bedrock quality. Seismic reflection survey mapped the subsurface stratigraphy with high resolution. Reservoir-bed and bedrock contours drawn from the results of the survey helped in choosing the tunnel alignment and the lake tap position cost effectively. It was inferred from the results of the survey that the geology and the quality of rock do not change unexpectedly around the site for extension of Head race tunnel and the lake tapping. The bedrock levels evaluated by seismic survey agreed remarkably well with those inferred in boreholes having Rock Quality Designation 90 percent or more.

• 한국지형공간정보학회:학술대회논문집
• /
• 2003.09a
• /
• pp.157-162
• /
• 2003

실시간 동적 GPS 측위를 이용한 해저수심측량은 GPS 수신기가 이동중인 상태에서 신호단절 없이 연속적인 수심측정이 가능하며 등수심도와 등고선 제작에 정확한 위치를 결정할 수 있고, 음향측심기는 발사파와 수신파의 도달시간을 측정하여 수심을 관측할 수 있기 때문에 실시간으로 정확한 3차원 측량이 가능하다. 본 논문에서는 해안지역에 대한 지형 분석을 하기 위하여 기준점에 대한 정지관측을 실시하여 좌표변환계수를 산출하고, 이로부터 실시간 동적 GPS 측량과 음향측심기를 이용하여 해운대 해수욕장과 해안을 관측하였다. 1:1,200 축척의 수치지도에서 추출한 수치표고모델에서의 체적은 $97953.9m^3$이며, 실시간 동적 GPS와 음향측심기를 이용하여 추출한 수치표고모델에서의 체적은 $95994.9m^3$로 나타났다. 이는 수치지도에서의 체적과 측량결과의 체적이 단지 2.0%정도로 나타나 실시간 동적 GPS와 음향측심기의 결합에 의한 해저수심측량이 매우 성공적임을 알 수 있었다.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 1994.11a
• /
• pp.183-186
• /
• 1994

Porous piezoelectric ceramics of P7T have been newly developed to apply for transducers in an echo sounder PZT powders were prepared by the molten salt synthesis method. The porous PZT was prepared from a mixture of PZT and polyvinylalcohol(PVA) powders by BURPS(Burnout Plastic Sphere) technique. The piezoelectric and acoustic properties with various PVA wt.% have studied. The density of porous PZT ceramics was decreased linearly with increasing the PVA sphere wt.%. Piezoelectric coefficient d$\_$33/ of porous PZT ceramics was almost same to that of single phase PZT ceramics. The thickness mode coupling factor k$\_$t/ was ranged over 0.53∼0.59 comparable with the single phase PZT ceramics(k$\_$t/=0.7).