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이성기,이광재,유강수,곽훈성,Lee Sung-ki,Lee Kwang-jae,You Kang Soo,Kwak Hoon Sung 한국통신학회 2005 韓國通信學會論文誌 Vol.30 No.11A
본 논문에서는 기존 단극성 원 빔(one beam) 레이저 방식의 단점을 개선한 차량용 듀얼 빔 레이저 레이더 시스템을 설계하였다. 양극성 m-시퀀스를 두 개의 레이저 파장에 할당함으로써 2차원 OOC(orthogonal optical codes)와 유사한 특성을 갖도록 하고 수신부에서 두 개의 단극성 신호를 차동구조를 이용하여 양극성 신호로 합성하는 방법을 이용한 SNR 개선 방안을 제시하고 이의 성능을 분석하였으며, 시뮬레이션 결과, 제안하는 듀얼 빔 방식이 기존 원 빔 단극성 신호방식의 레이저 레이더 시스템에 비해 3dB의 SNR 개선이 가능함을 확인하였다. 또한 차등구조를 이용한 간단한 간섭제거 기법을 제시하였다. 제안한 방식은 단극성 광 신호를 기반으로 제안된 최근의 우수한 연구 결과들에 적용함으로써 3dB의 SNR 이득을 추가로 확보할 수 있는 장점이 있다. In this paper, we develop a dual beam automotive laser radar system which improve the defect of conventional unipolar one beam laser scheme. We introduce an SNR improving method using bipolar signal synthesizing scheme from two unipolar signals at the receiving unit via differential structure by allocating bipolar m-sequence into the two laser wavelengths, which have similar property like 2-D OOC, and investigate its performance. Simulation results show that the proposed dual beam scheme can have 3dB SNR improvement as compared with conventional unipolar signaling laser radar system. Also, we show the simple interference rejection scheme using differential structures. The proposed scheme have a merit to obtain additional 3dB SNR gain applied into the excellent results based on unipolar optical signal studied lately.
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이성기,김기성,신동화,강통삼,송계원 ( S . K . Lee,K . S . Kim,D . H . Shin,T . S . Kang,K . W . Song ) 한국축산학회 1986 한국축산학회지 Vol.28 No.10
The ripening characteristics of country-style ham were compared with one another among various curing formula. Raw meats were cured with 20, 30, 40, 50% sucrose content of curing mixtures. Hams were prepared by curing 5℃ for 1 month followed by holding at 11℃±1℃ for 1 month and then ripened 4 months at 27℃±1℃ and RH 65-80%. pH of all samples showed an increase from 5.52-5.87 to 6.37-6.44 during ripening. It increased remarkably for the sample with the higher sucrose content. Free amino nitrogen (NH₂-N) increased to 48.9-61.0 ㎎% at the end of the ripening period. Its concentration was also higher as the sucrose content increased. Residual nitrate and nitrite were sharply depleted during the first month of ripening, then changed slowly. At the second month ripening, they were 80 ppm and 50 ppm, respectively. Almost all of ATP, AMP disappeared in various samples although the initial contents were very low. But the remaining amount of ADP was considerably high (1.1-7.4 μmole/g meat) while the other nucleotides almost entirely disappeared. IMP tended to degrade rapidly during ripening. Hypoxanthine accumulated about 5.0-9.3μmole/g at the first month ripening then degraded slowly. Microbial counts generally increased as storage temperature increased. Total plate count and lactic acid bacteria count increased during the first month of ripening (1.8×10^7 and 2.8×10^6 cells/g, respectively), then decreased slowly.
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BB절리모델을 활용한 절리암반속 터널안정성의 수치해석적 연구
이성기,정형식,Lee, Sung-Ki,Chung, Hyung-Sik 한국터널지하공간학회 2001 터널기술 Vol.3 No.3
For the pertinent use of NMT method, both characteristics of joints (JRC, JCS and ${\phi}_r$) and characteristics of rock mass (Q-Value) must be investigated carefully. The main objective of the study presented is to investigate how sensitive the predicted behaviour of an underground excavation is to various realistic assumptions about some input parameter for the jointed rock mass. Joint pattern in the tunnel is predicted by statistical approach (chi-square test). In this paper, sensitivity studies involving in joint characteristics were carried out. The parametric studies involving change in Barton-Bandis joint model have shown that JCS is relatively insensitive to JRC and ${\phi}_r$. An increase in JRC value may not, according to the Barton-Bandis model, necessarily lead to a decrease in displacement. The importance of dilation in predicting the behaviour of a rock mass around an excavation is emphasized from a comparison of the Barton-Bandis joint behaviour model with the Mohr-Coulomb model. The Barton-Bandis model predicted higher stress, which allow for the build-up of stress caused by dilatant behaviour. NMT 공법의 올바른 적용을 위해선 암반속 절리면 거동분석이 선행되어야함을 인식하고 절리면의 전단특성 및 구성모델을 검토하였다. 특히, Barton-Bandis 모델로 대변되는 비선형 절리 모델의 정확한 이해와 모델을 구성하고 있는 제반 물성치의 합리적인 산출을 위하여 암반의 불연속체 거동을 지배하는 중요인자인 절리면 거칠기(JRC), 절리면 압축강도(JCS) 및 잔류마찰각(${\phi}_r$)에 대한 매개변수 분석을 수행하여 합리적인 입력값 산정이 가능하도록 하였다. 또한 Barton-Bandis 모델과 Mohr-Coulomb 모델과의 비교분석을 통하여 불연속체 거동 특성파악을 위한 구성모델을 검토하고자 하였다. 본 연구 결과 JRC 및 ${\phi}_r$의 영향이 JCS에 비해 상대적으로 큰 것으로 평가되었으며, 터널안정 해석시에 낮은 JRC 값을 채택하는 것이 반드시 불안전측을 고려하는 것은 아님을 알 수 있었으며, ${\phi}_r$은 암반의 거동에 큰 영향을 주는 매우 중요한 요소이므로 ${\phi}_r$값에 대한 합리적인 산정이 필요한 것을 알 수 있었다. 아울러 전단시 절리면의 팽창효과가 암반의 거동에 중요한 역할을 하는 경우, 전단변형 진행에 따라 절리면의 거동을 효과적으로 구현할 수 있는 Barton-Bandis 모델이 Mohr-Coulomb 모델에 비해 더욱 적절함을 알 수 있었다.
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합차신호를 이용한 차량용 듀얼 빔 레이저 레이더의 견고한 탐지 능력 향상 방안
이성기,유승선,유강수,김삼택,Lee Seung-Gi,Yoo Seung-Sun,You Kang-Soo,Kim Sam-Tek 한국통신학회 2006 韓國通信學會論文誌 Vol.31 No.7C
본 논문에서는 두 개의 다른 밀리미터 파장을 적용하는 광전계통의 구조 변경을 시도하고 신호 흡수나 환경적 간섭 왜곡에 취약한 싱글 빔(single beam) 레이저 방식의 단점을 보완한 듀얼 빔(dual beam) 방식의 레이저 레이더 시스템을 제안한다. 본 논문에서 제한 한 듀얼 빔 방식 레이더 시스템은 적은 신호 검파의 신뢰성 측면에서 통계적이며 분석적인 방법으로 제안하여 시스템의 우수성을 입증하고 AWGN 배경 잡음과 흡수 또는 간섭에 의해 레이저 신호의 왜곡이 발생하는 채널환경에서 시뮬레이션을 수행함으로써 신호 검파의 신뢰성 향상이 가능하다는 분석적 결과에 대한 정량적 재검증을 한다. In the proposed method, two regular laser working at two different wavelengths perform moving object detection alternatively in time. The laser intensity and the beaming period of each laser is equally maintain as to the single laser radar, hence, externally, dual beam lasers radar works exactly same as the single beam laser radar except that the proposed dual lasers radar needs additional post-processing of received signals in the receiver. To verify the robustness of the proposed method, a set of computer simulation has been performed. The communication channel is assumed to be additive white Gaussian noise, and the perfect synchronization is assumed. All other simulation parameters such as signal power and signalling period are equally maintain in both systems while the signal processing time such as spreading and filtering are expected to be trivial in call cases.
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아질산염 , 아스코르부산 및 소금의 첨가수준이 세절육 ( 細切肉 ) 의 특성에 미치는 영향
이성기,송계원 ( Sung Ki Lee,Kai Won Song ) 한국축산학회 1983 한국축산학회지 Vol.25 No.4
This experiment was carried out to determine the effect of sodium nitrite, ascorbic acid and sodium chloride on the characteristics of ground meat model systems. The fresh pork was ground and mixed with or without sodium nitrite (0, 68, 136, 180 ppm), ascorbic acid (0, 545 ppm) and sodium chloride (0, 2.0, 3.5, 5.0%). The results obtained were summarized as follows. 1. The pH of all the samples was in the range of pH 5.5-6.1. Samples mixed with sodium nitrite had a lower pH than those mixed with salt alone. Samples with sodium nitrite or ascorbic acid (AS) had a pH lower than no added samples. 2. Nitrite was more rapidly decrease when ascorbate (545 ppm) was added. After 5 days of storage, 14-38% of the originally added nitrite remained in ascorbate free samples but only 2.2-2.9% remained in treated ascorbate samples, Residual nitrite was higher in the presence of large amounts of sodium chloride. 3. The color intensity of nitrite added samples increased in proportion to its concentration. An increase in color development with length of storage period also apparent. Especially, color intensity was superior in NaNO₂ (182 ppm)+AS (545 ppm) sample. 4. Inhibition of microbial growth did not appear to remarkably influence the concentrations of sodium nitrite or ascorbic acid. However, salt concentration had highly inhibitory effect on aerobic bacteria counts. 5. Samples with nitrite revealed a remarkable reduction in TBA number. Especially, NaNO₂ (182 ppm)+Salt (3.5%) and NaNO₂ (136 ppm)+Salt (3.5%) samples were noticeable retardation of the natural oxition. Salt alone concentrations promoted greater rate of rancidity development.
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