• 한국신재생에너지학회:학술대회논문집
• /
• 2007.11a
• /
• pp.59-62
• /
• 2007

연료전지는 수소를 이용하여 전기를 생산하는 발전 시스템으로 운전 중 수소 누출과 폭발의 위험성을 항상 수반하고 있다. 따라서 안전성의 확보를 위해 연료전지 시스템 내부에서 수소 누출 시 유e동 특성으로 인한 특정 부근 농도 정체와 환기의 영향을 파악하는 것이 필요하다. 실험 장치와 전산유체역학 프로그램을 사용하여 챔버 내 수소의 유통 특성과 환기구에 따른 환기의 영향을 확인하였다. 수소의 누출 속도와 양에 따라 유동장의 형태는 크게 변하였으며 환기구의 위치와 크기는 특정 부근의 농도정체와 챔버 내 전체적인 수소 농도에 영향을 미침으로서 안정성을 확보하는 중요한 인자임을 알 수 있었다. 예측 결과를 실제 실험 모델과 비교하여 그 타당성을 검토하였으며 차후 가정용 연료전지 모듈의 환기구 설계에 적용할 수 있다.

• Journal of the Korea Institute of Military Science and Technology
• /
• v.9 no.3
• /
• pp.48-55
• /
• 2006

This paper describes the antenna based GPS anti-jamming technology called CRPA(Controlled Reception Pattern Antenna), which used $2{\times}2$ array elements. In this system, the main functions are the antenna complex weight control and the GPS digital I/Q VM(Vector Modulator). To update the VM's I/Q complex weights, the PC based DAC(Digital to Analog Converter) module was also used and the two analog output voltages were applied to the $2{\times}2$ array elements to synthesize the null pattern. In the study, we also simulated the $2{\times}2$ GPS array null patterns to compare the null depth with experimental results. The VM was also modified at the frequency of 1.575GHz for the GPS L1 and controlled by the PC based VM software.

• Journal of the Korea Institute of Military Science and Technology
• /
• v.7 no.2 s.17
• /
• pp.48-56
• /
• 2004

This paper presents the GPS receiver's inherent interference effectiveness based on the receiver's internal processing gain. This research is to verify the weakness of the GPS satellite signals and evaluate the receiver's vulnerability in an interference situation. The experiment for the narrow band interference effectiveness for the L1 C/A code GPS receiver has been performed by using the Spirent GSS4765 jamming simulator. After analyzing the experimental result, it is compared with the calculated J/S value of the two different L1 C/A code GPS receivers. By the above result, the narrowband jamming effectiveness of the each jamming source and the jamming margin for the each receiver are to be analyzed in detail. Finally, we could utilize the result to analyze the jamming effectiveness on the GNSS receiver.

• Journal of the Korea Institute of Military Science and Technology
• /
• v.9 no.1 s.24
• /
• pp.5-12
• /
• 2006

This study describes an SDINS/GPS/ZUPT integration algorithm for land navigation systems. The SDINS error can be decoupled in two parts. The first part is the the Schuler component which does not depend on object motion parameters, and the other is the Non-Schuler part which depends on the product of object acceleration and azimuth error. Azimuth error causes SDINS error in proportion to the traversed distance. The proposed system consists of a GPS/SDINS integration system and an SDINS/ZUPT integration system, which are both realized by an indirect feedforward Kalman filter. The main difference between the two is whether the estimate includes the Non-Schuler error or not, which is decided by the measurement type. Consequently, subtracting GPS/SDINS outputs from SDINS/ZUPT outputs provide the Non-Schuler error information which can be applied to improving azimuth accuracy. Simulation results using the raw data obtained from a van test attest that the proposed SDINS/GPS/ZUPT system is capable of providing azimuth improvement.

• Journal of the Korean Society for Aeronautical & Space Sciences
• /
• v.44 no.9
• /
• pp.781-788
• /
• 2016

In this paper, a real-time on-board orbit determination algorithm using the high precise orbit propagator is suggested and its performance is analyzed. Orbit determination algorithm is designed with the Extended Kalman Filter. And it utilizes the orbit calculated from the Pseudo-range as observed data. The performance of the on-board orbit determination method implemented in the GPS-12 receiver is demonstrated using the GNSS simulator. Orbit determination performance using high precise orbit propagator was analyzed in comparison to the orbit determination result using $J_2$ orbit propagator. The analysis result showed that position and velocity error are improved from 43.61 m($3{\sigma}$) to 23.86 m($3{\sigma}$) and from 0.159 m/s($3{\sigma}$) to 0.044 m/s($3{\sigma}$) respectively.

• Journal of the Korean Society for Aeronautical & Space Sciences
• /
• v.45 no.2
• /
• pp.106-113
• /
• 2017

Attitude determination algorithms for aircraft and land vehicles use earth gravitational vector and geomagnetic vector; hence, magnetometers and accelerometers are employed. In dynamic situation, the output from accelerometers includes not only gravitational vector but also motional acceleration, thus it is hard to determine accurate attitude. The acceleration compensation method treated in this paper solves the problem to compensate the specific force vector for motional acceleration calculated by a GPS receiver. This paper analyzed the error from the corrected vector regarded as a constant by conventional acceleration compensation method, and improve the error by rederivation from measurements. The analyzed error factors and improvements by the proposed algorithm are verified by computer simulations.

• Korean Journal of Heritage: History & Science
• /
• v.44 no.1
• /
• pp.52-71
• /
• 2011

This study was initiated with the intent to consider the features of Gugokwonlim and to compare Gabsagugok(甲寺九曲) to Yongsangugok(龍山九曲) against the backdrop of Mt. Gyeryong by revealing their nature and confirming the names and exact locations. A literature review, interviews with local people and field studies confirmed that Gabsagugok and Yongsangugok are each composed of 9 seasonal features. The former is made up of Yongyuso(龍遊沼) - Iilcheon(二一川) - Baengnyonggang(白龍岡) - Dalmuntaek(達門澤) - Geumgyeam(金鷄?) - Myeongwoldam(明月潭) - Gyemyeongam(鷄鳴巖) - Yongmunpok(龍門瀑) - Sujeongbong(水晶峰) while the latter is made up of Simyongmun(尋龍門) - Eunnyongdam(隱龍潭) - Waryonggang(臥龍剛) - Yuryongdae(遊龍臺) - Hwangnyongam(黃龍岩) - Hyeollyongso(見龍沼) - Ullyongtaek(雲龍澤) - Biryongchu(飛龍湫) - Sillyongyeon(神龍淵). Both Gabsagugok and Yongsangugok are part of Gugokwonlim built in the valleys of Mt. Gyeryong in the late Joseon Dynasty by Byeoksu Yun Deok-yeong (1927) and Chwieum Gwon Jun-myeon (1932), respectively, with a 5 year difference. Gabsagugok was supposedly designed to reflect an individual taste for the arts and to admire principles of Juyeok (ch. Zhouyi) and the beauty of nature. On the contrary, Yongsangugok appears to be the builder's expression of his longing for independence day, likened to the life of a dragon after receiving the sad news of Japan's annexation of Korea. Such differences show that these two builders had very different intentions from one another. The letters of Gabsagugok have a semi cursive style and were deeply engraved on the rock in a square shape. Consequently they have not been worn away except for those in Yongyuso, the first Gok. In contrast, the letters in Yongsangugok have an antiquated, cursive-Yija style but because they were engraved relatively lightly, serious wear and damage occurred. In terms of location, Gabsagugok was built around Ganseongjang adjacent to the 5th Gok while Yongsangugok was set up around the 5th Gok, Hwangnyongam. Meanwhile, the important motif which forms the background of Gabsagugok seemingly highlights the geographic identity of Mt. Gyeryong using the dragon and the chicken as themes. It also appears to symbolize the principles of Juyeok focusing on Kan of the Eight Trigrams for divination; this requires an in-depth study for confirmation. The main motif and theme of Yongsangugok is the dragon. It infuses the builder's intentions in Sangsinri Valley by communicating with nature through a story of a dragon's life from birth to ascension. It is assumed that he tried to use this story to express his hope for restoring the national spirit and reconstructing the country.