• 수산해양기술연구
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• 제41권1호
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• pp.70-77
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• 2005

연근해 어선에서 사용되는 저가이면서 고정도의 GPS 컴퍼스는 위성 신호의 차단 및 선박이 고속 선회시 선수방위의 산출이 불안정해지는 문제점을 지니고 있어 전자자기 컴퍼스를 이용하여 안정된 선수방위 검출이 가능하도록 고안한 하이브리드 GPS-전자자기 컴퍼스를 시작(試作)하여, 그 성능을 평가하고 고찰한 결과는 다음과 같다. 스텝모터를 이용한 선회각속도별 실험에서 GPS 컴퍼스는 선회각속도 25^{\circ}$/sec 이하에서는 1회/sec 씩 0.1^{\circ}$ 단위로 안정된 선수방위를 검출하였으나, 그 이상의 선회각속도에서는 선수방위를 검출하지 못하였다. 한편, 전자자기 컴퍼스는 선회각속도에 상관없이 항상 선수방위를 나타내었으나, 컴퍼스 오차를 내포하고 있어 GPS 컴퍼스에 비해 정밀도는 낮음을 알 수 있었다. 고정점과 차량으로 이동 중에 하이브리드 GPS-전자자기 컴퍼스의 선수방위 정보를 출력한 결과, GPS 컴퍼스가 정상적으로 작동한 경우에는 GPS 컴퍼스의 선수방위 정보가 출력되고, 그렇지 못할 경우에는 선수방위 정보가 출력되고, 그렇지 못할 경우에는 전자자기 컴퍼스의 선수방위에 컴퍼스 오차를 가감하여 출력됨으로써 선수방위가 안정적으로 제공되었다. 또한, GPS 컴퍼스와 전자자기 컴퍼스에 의한 선수방위의 유사성을 검증하기 위하여, 두 데이터의 이동거리에 대한 선수방위를 이용하여 공분산분석을 행한 결과, 두 컴퍼스의 선수방위는 95%의 신뢰수준으로 유사성이 검증되었다.

• 수산해양기술연구
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• 제22권1호
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• pp.1-5
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• 1986

In order to improve the net-mouth height of dragged gears, the authors devised models of floatingcollars of nylon cloth instead of floats and experimented with 4 types-A type (length 65em, breadth 3em), B type (length 65em, breadth 4em), C type (length 65em, breadth 5em) and D type (length 65 em, breadth 6em) attached respectively to the front edge of square of a model net after preliminary experimentation. These various types of floating collars were experimented in a circulating water channel to evaluate the characteristics of net-mouth height and hydrodynamic resistance and the effect of the length of bridles were also examined. The results obtained were as follows: 1. In case of attaching floats, the model net-mouth height reduced from 80 em to 20 em when current velocity was increased from 0.25m/see to 1m/sec. 2. In case of attaching floating collars, the model net-mouth heights were maintained 70 em, 71 em, 80 em, 78 em in maximum and 55 em, 63 em, 69 em, 73 em in minimum respectively even the current volocity was increased from 0.25 m/see to 1 m/see. 3. The model net-mouth height was reduced to 10 em maximum according to the current velocity and types of floating collars when the bridles were shortened 3~4 mm in length. 4. Hydrodynamic resistance of D type only was increased to 700 g in maximum and those of A, B, C type were reduced to 460 g in maximum at current velocity beyond 0.5 m/ see when bridles were shortened 3-4 mm in length. 5. But the model net-mouth heights became higher in accordance with breadth of floating coliars, B type was the best for this model net in case that hydrodynamic resistance was taken into account.

• 대한전기학회논문지:전기물성ㆍ응용부문C
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• 제48권6호
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• pp.436-441
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• 1999

Joule heating effect in EM(Electromigration) test were performed on a bend test structure. EM test is done under high current densities(1.0-2.5MA/cm2), which leads to joule heating. Since joule heating is added to the controlled oven(stress) temperature, themetal line temperature is higher than the stress temperature. The increase in the stress temperature due to joule heating is important because EM phenomena and metal line failure are related to the stress temperature. In this paper, metal line was stressed with a current density of 1.0 MA/$cm^2$, 1.5MA/$cm^2$, 2.0MA/$cm^2$, 2.5MA/$cm^2$, for 1200 sec and temperature increase due to joule heating was less than $10^{\circ}C$. Also it took 30 minutes for the metal line to equalized with oven temperature. Recommendations are given for the EM test to determine the initial resistance of EM test structure under stress temperature and current density.

• The Korean Journal of Ecology
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• 제3권1_2호
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• pp.31-39
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• 1980

지상에 떨어진 Opuntia bigelovii 선인장의 줄기에 있어서 광 energy의 이용한계와 함수량과의 관계를 연구하였다. 이들 떨어진 선인장의 줄기는 주.야로 줄기확산저항이 256.0~310.4 sec $cm^{-1}$인 것으로 보아 기공은 주.야를 통하여 폐공하고 있음을 알 수 있었다. 또한 축적된 산의 감소율은 PAR이 1000${\mu}Em^{-2}sec^{-1}$인 조건 하에서 4시간이면 steady state로 감소하였다. 조직내의 산감소율은 조직의 함수량에 따라 감소하며 그 함수량이 56.4~46.8% 일때에는 4시간 동안의 광조사와 본실험방법으로는 거의 산감소율을 확인할 수 없었다. 일주기 rhythm에 의하여 나타나는 산도의 oscillation도 조직의 함수량으 감소에 따라 감소하였다. 한마디의 선인장줄기가 사막의 땅에 떨어져 두마디의 선인장이 되는 생존율을 22.7%였으며 그동안은 외부로 부터 $CO_2$와 물의 흡수없이 광energy를 이용하여 생존하고 비가 내리자 않는 긴 건조기에도 선인장은 똑같은 방법으로 생활한다는 것은 알 수 있었다. 이와 같이 외부로 부터 들어오는 광과 호흡에 의하여 내생되는 $CO_2$만을 이용하는 보상광합성의 대사과정을 model로 제시하였다.

• 자원환경지질
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• 제31권1호
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• pp.53-57
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• 1998

Transient electromagnetic (TEM) method is also affected by cultural and natural electromagnetic (EM) noises, since it uses part of the broadband ($10^{-2}$ to $10^5Hz$) spectrum. Especially, predominant EM noise which affects a moving transmitter-receiver TEM system is sensor motion-induced noise. This noise is caused by the sensor motion in the earth magnetic field. The technique for reducing the sensor motion-induced EM noise presented in this paper is based on Halverson stacking. This Halverson stacking is generally used in a time-domain induced polarisation (IP) system to reject DC offset and linear drift. According to spectrum analysis of the vertical component of sensor motion-induced noise, the frequency range affected by the motion of an EM sensor is less than about 700 Hz in this study. With the decrease of the frequency, the spectral power caused by the motion of a sensor increases. For example, at the frequency of 200 Hz, the spectral power of the sensor motion-induced noise is $-90dBVrms^2$ while the spectral power of the EM noise measured with a fixed sensor on the ground is $-105dBVrms^2$, and at the frequency of 100 Hz, the spectral power of the sensor motion-induced noise is $-70dBVrms^2$ while the spectral power of the EM noise measured with a fixed sensor on the ground is $-105dBVrms^2$. With applying Halverson stacking to an artificial noise transient generated by adding a noise-free transient to sensor motion-induced noise measured without pulsing, it is shown that the filtered transient is nearly consistent with the noise-free transient within a delay time of $0.5{{\mu}sec}$. The inversion obtained from this filtered transient is in accord with the true model with an error of 5%.

• 한국동물번식학회:학술대회논문집
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• 한국동물번식학회 2003년도 학술발표대회 발표논문초록집
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• pp.29-29
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• 2003

The objective of this study is to examine an effective cryopreservation method and various vitrification containers on the survival vates of embroys. For the vitrification, in vitro produced embryos at blastocyst stage were exposed to ethylene glycol 5.5 M freezing solution (EG5.5) for 20 sec, loaded on containers such as grid, straw and paper and then immediately plunged into - 196$^{\circ}C$ L$N_2$. The blastocysts were thawed serially in 0.5, 0.25 and 0.125%; P < 0.05). Therefore, this study suggests that bovine embryos can be easily, effectively and successfully cryopreserved by grid, straw, and paper in the presence of freezing solution. Furthermore, vitrification using paper may be used as a no M sucrose in CR1aa, each for 1 min, and cultured in CR1 an medium supplemented with 10% FBS. After thawing, there were not significant differences in recovery rates of EM grid, straw and paper as 84.6, 88.3, and 93.7%, respectively (Table 1). However, survival rates of EM grid (78.1%) and paper (77.1%) showed significantly higher than straw (52. 1w method for bovine embryos.

• 한국정보과학회:학술대회논문집
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• 한국정보과학회 1999년도 가을 학술발표논문집 Vol.26 No.2 (2)
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• pp.548-550
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• 1999

무인 주행 차량에 있어서, 포장 또는 비포장 도로의 시각적 추적은 매우 중요한 문제중의 하나이다. 따라서, 비디오 이미지로부터 비포장 도로를 추적할 수 있는 신속한 비젼 알고리즘의 개발이 필요하다. 이 논문에서는 칼만 필터와 EM(Expectation Maximization) 이론을 이용해 도로를 예측하고 시스템 파라미터를 갱신하는 방법을 제시한다. 시스템 파라미터, 도로 state, 도로 경계선, 그리고 모든 과거 데이터들을 각각 EM 파라미터, hidden data, incomplete data와 complete data로 정의함으로서 도로 state를 예측하고 시스템 파라미터를 추정할 수 있는 시간 회귀적 수식을 유도해 낼 수 있다. 이러한 방법을 이용하여 도로 state는 칼만 필터에 의해 매 프레임마다 예측되며, 시스템 파라미터들은 주기적으로 갱신되는 것이다. 결과적으로 이 방법은 주변환경과 날씨에 많은 영향을 받는 도로의 모양과 특징을 잘 찾아낼 수 있다. 또한 도로의 다음 state를 예측할 수 있는 점을 이용하면 계산량을 줄일 수 있으므로 실시간 구현에 용이하다. 이와 같은 방법으로 우리는 0.1 sec/frame 처리속도를 보장하는 도로추적 시스템을 구현하였다.

• 한국동물번식학회:학술대회논문집
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• 한국동물번식학회 2001년도 춘계학술발표대회
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• pp.76-76
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• 2001

The objective of this study was to optimize the vitrification method of in vitro produced bovine embryos. Thus, in vitro produced embryos at 8 cell, morula and blastocyst stages were vitrified on electron microscope grids (EM grids) or in open pulled straws (OPS) with EG5.5 (5.5 M ethylene glycol, 1.0 M sucrose and 10% FBS in m-DPBS medium) freezing solution and their survival rates after thawing were compared. The embryos on EM grids or in OPS were briefly exposed to EG5.5 freezing solution and plunged directly into liquid nitrogen within 30 to 35 sec. Post-thawed embryos were serially diluted in 0.5, 0.25 and 0.125 M sucrose in m-DPBS, each for 1 min, and then cultured in CRI aa medium supplemented with 10% FBS. Embryonic survival rate was assessed as re-expanded and hatched rates of those embryos after warming. The rates of re-expansion embryos did not significantly different between EM grid (8 cell: 42.10%, morula: 66.66% and blastocyst: 77.08%) and OPS (8 cell: 47.36%, morula: 61.90% and blastocyst: 83.33%) methods. In addition, the hatched rates in EM grid (8 cell: 31.57%, morula: 57.14% and blastocyst: 72.91%) were similar to those in OPS (8 cell. 34.21%, morula: 50.00% and Blastocyst: 77.08%). Interestingly, even at the same blastocyst stage, the in vitro survival of day 7 embryos (EM grid: 79.48 and OPS: 87.18%) was higher than those of day 8 embryos (EM grid: 72.10 and OPS: 82.06%). The total cell number of blastocyst developed in vitro after vitrification was examined with Hoechst 33342 staining to compare the embryo quality among different treatment groups. The total cell number of blastocyst was not significantly different between vitrified groups (EM grid: 162.4$\pm$8.0 and OPS: 158.4$\pm$7.1) and unvitrified control (168.0$\pm$5.6). These results indicate that both vitrification containers can provide the high rate of embryo survival. Moreover, the OPS container may not need a cap to protect the container from floating after immersion in L$N_2$. Therefore, this study suggest that bovine embryos can be cryopreserved easily, effectively and successfully by vitrification method using EM grid or OPS with EG5.5 freezing solution. In the future, the Pregnancy rate would be investigated after transfer of our vitrified embryos into the appropriated recipients.

• 수산해양기술연구
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• 제33권4호
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• pp.360-369
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• 1997

We calculated the residual current forced by buoyancy, wind stress, and tidal stress in the Chinhae Bay using a three-dimensional diagnostic model. The calculated current was also compared with the observation. The flow directs outward from the central area of the Bay in the upper layer, and also forms eddy-shape stucture in the upper and middle layers. The flow of bottom layer shows an opposite pattern compared to those of top and middle layers. The maximum speed was 6.05 em/see (September) and 3.49 cm/sec (November) in the upper layer, and 4.39 cm/sec on both month in the middle layer. The Kinetic energy of November (8.39xlO' W) was larger than that of September (1.24xlO 'W), mainly resulting from larger buoyancy effect in September. In spite of the roughness of the grid size(1 km) and wind date, the calculated flow shows eorrelation(r=0.71) with the observation. We expect that the correlation be increased by increased by adopting the fine grid and the variable coefficients of diffusion and viscosity.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2004년도 제22회 춘계학술대회논문집
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• pp.205-210
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• 2004

The pulse detonation engine (PDE) has recently expected as a new aerospace propulsion system. The PDE system has high thermal efficiency because of its constant-volume combustion and its simple tube structure. We measured thrust of single-tube pulse detonation rocket (PDR) by two methods using the PDR-Engineering Model (full scale model) for ground testing. The first involved measuring the displacement of the PDR-EM by laser displacement meter, and the second involved measuring the time-averaged thrust by combining a load cell and a spring-damper system. From these two measurements, we obtained 130.1 N of time-averaged thrust, which corresponds to 321.2 sec of effective specific impulse (ISP). As well, we measured the heat flux in the wall of PDE tubes. The heat flux was approximately 400 ㎾/$m^2$. We constructed the PDR-Flight Mode] (PDR-FM). In the vertical flight test in a laboratory, the PDR-FM was flying and keeping its altitude almost constant during 0.3 sec.