• Asian-Australasian Journal of Animal Sciences
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• v.30 no.7
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• pp.985-993
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• 2017

Objective: The objective of this study was to evaluate increasing doses of a novel microbial phytase (Cibenza Phytaverse, Novus International, St. Charles, MO, USA) on standardized total tract digestibility (STTD) of P in canola meal (CM), corn, corn-derived distiller's dried grains with solubles (DDGS), rice bran (RB), sorghum, soybean meal (SBM), sunflower meal (SFM), and wheat. Methods: Two cohorts of 36 pigs each (initial body weight = $78.5{\pm}3.7kg$) were randomly assigned to 2 rooms, each housing 36 pigs, and then allotted to 6 diets with 6 replicates per diet in a randomized complete block design. Test ingredient was the only dietary source of P and diets contained 6 concentrations of phytase (0, 125, 250, 500, 1,000, or 2,000 phytase units [FTU]/kg) with 0.4% of $TiO_2$ as a digestibility marker. Feeding schedule for each ingredient was 5 d acclimation, 5 d fecal collection, and 4 d washout. The STTD of P increased (linear or exponential $p{\leq}0.001$) with the inclusion of phytase for all ingredients. Results: Basal STTD of P was 37.6% for CM, 37.6% for corn, 68.6% for DDGS, 10.3% for RB, 41.2% for sorghum, 36.7% for SBM, 26.2% for SFM, and 55.1% for wheat. The efficiency of this novel phytase to hydrolyze phytate is best described with a broken-line model for corn, an exponential model for CM, RB, SBM, SFM, and wheat, and a linear model for DDGS and sorghum. Based on best-fit model the phytase dose (FTU/kg) needed for highest STTD of P (%), respectively, was 735 for 64.3% in CM, 550 for 69.4% in corn, 160 for 55.5% in SBM, 1,219 for 57.8% in SFM, and 881 for 64.0% in wheat, whereas a maximum response was not obtained for sorghum, DDGS and RB within the evaluated phytase range of 0 to 2,000 FTU/kg. These differences in the phytase concentration needed to maximize the STTD of P clearly indicate that the enzyme does not have the same hydrolysis efficiency among the evaluated ingredients. Conclusion: Variations in enzyme efficacy to release P from phytate in various feedstuffs need to be taken into consideration when determining the matrix value for phytase in a mixed diet, which likely depends on the type and inclusion concentration of ingredients used in mixed diets for pigs. The use of a fixed P matrix value across different diet types for a given phytase concentration is discouraged as it may result in inaccurate diet formulation.

• Proceedings of the IEEK Conference
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• 2004.06a
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• pp.79-82
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• 2004

In this paper, we analyze the performance of high-rate OFDM(Orthogonal Frequency Division Multiplexing) in the JTC(Joint Technical Committee) channel models using transmit diversity. In this thesis, each independent channel characteristic antennas in the transmitter are analyzed. Also, Equalization method through the channel estimation in the realistic fading channel environments is applied for BEE 802.11a WLAN system performance. From the simulation results, BER through transmit diversity of WLAN system is evaluated in AWGN channel and multipath channel environments.

• Proceedings of the Korean Information Science Society Conference
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• 2003.10c
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• pp.172-174
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• 2003

송신단에 다중안테나를 사용하는 송신 다이버시티 기법에 대한 연구가 최근 활발히 이루어지고 있다. 본 논문에서는 CDMA(Code Division Multiple Access)2000과 3GPP(The third generation partnership project)에서 고려한 개루프 송신 다이버시티 기법인 STTD(Space time transmit diversify), OTD (Orthogonal transmit diversity), STS(Space time spreading)를 다수 반송파 CDMA 시스템에 적용시킬 경우 하향링크 (Downlink)에서의 성능을 평가한다. STS와 STTD방식은 동일한 성능을 보이지만 STS방식은 복잡도와 높은 PAR(Peak to average ratio)의 단점을 보이며, OTD는 이 두 방식에 비해 성능이 떨어지는 것을 보여준다.

• Animal Bioscience
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• v.36 no.2
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• pp.167-174
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• 2023

Phosphorus (P) is a macro mineral needed for bone mineralization and cell membrane structure and P is also involved in several fundamental pathways of metabolism in the body. Because of the low concentration and digestibility of P in plant ingredients that are the main components of diets for poultry and pigs, feed phosphates are usually included in diets in addition to the P contributed by plant ingredients. The most widely used feed phosphates in poultry and swine diets are dicalcium phosphate (DCP) and monocalcium phosphate (MCP), but tricalcium phosphate (TCP), monosodium phosphate (MSP), and magnesium phosphate (MgP) may be used as well. Because feed phosphates are mostly produced from rock phosphate, feed phosphates have impurities that contain minerals other than P. Concentrations of P in feed phosphates range from 14.8% (MgP) to 25.7% (MSP). The standardized total tract digestibility (STTD) of P in pigs ranges from 71% (TCP) to 95% (MSP). The STTD of Ca and the standardized ileal digestibility (SID) of P and Ca in feed phosphates fed to pigs and poultry have been determined only in a few experiments. Available data indicate that the STTD of Ca and SID of P in MCP are greater than in DCP in both poultry and pigs, but the SID of Ca is similar between DCP and MCP fed to broilers. Information on mineral concentrations and digestibility values in feed phosphates is needed in diet formulation for pigs and poultry, but if diets are formulated to contain equal concentrations of digestible P and Ca, it is unlikely that animal performance will be impacted by the source of feed phosphates used in the diet.

• Proceedings of the IEEK Conference
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• 2001.06a
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• pp.73-76
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• 2001

A key requirement for packet based wireless communication systems is to provide a high data rate packet service and improved throughput. To achieve a high throughput, adaptive methods for adjustment of the modulation and coding can be used. In this paper, we propose and analyze a scheme which is a combination of an adaptive modulation and coding(AMC) and transmit diversity(TD). Two different TD schemes are analysed: STTD and STD. Proposed system provides significant improvement in the average throughput.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.25 no.12A
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• pp.1796-1805
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• 2000

고속무선 이동 통신에서 가장 문제가 되는 것이 다중전송로에 의한 페이딩잡음이며, 이러한 페이딩의 문제점을 이동성을 보장하면서도 효율적으로 해결할 수 있는 방법이 최근 제안된 STTD(Space Time Transmitter Diversity) 기법이다. 본 논문에서는 상관된 Nakagami 페이딩 채널환경에서 적용될 수 있는 수신신호의 확률밀도함수를 유도하고 이 유도된 새로운 화률밀도함수를 이용하여 비동기 송신 다이버시티 시스템의 성능을 비교 분석한다.

• Asian-Australasian Journal of Animal Sciences
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• v.27 no.1
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• pp.1-9
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• 2014

Calcium (Ca) and phosphorus (P) are minerals that have important physiological functions in the body. For formulation of diets for pigs, it is necessary to consider an appropriate Ca:P ratio for an adequate absorption and utilization of both minerals. Although both minerals are important, much more research has been conducted on P digestibility than on Ca digestibility. Therefore, this review focuses on aspects that are important for the digestibility of Ca. Only values for apparent total tract digestibility (ATTD) of Ca have been reported in pigs, whereas values for both ATTD and standardized total tract digestibility (STTD) of P in feed ingredients have been reported. To be able to determine STTD values for Ca it is necessary to determine basal endogenous losses of Ca. Although most Ca is absorbed in the small intestine, there are indications that Ca may also be absorbed in the colon under some circumstances, but more research to verify the extent of Ca absorption in different parts of the intestinal tract is needed. Most P in plant ingredients is usually bound to phytate. Therefore, plant ingredients have low digestibility of P due to a lack of phytase secretion by pigs. During the last 2 decades, inclusion of microbial phytase in swine diets has improved P digestibility. However, it has been reported that a high inclusion of Ca reduces the efficacy of microbial phytase. It is possible that formation of insoluble calcium-phytate complexes, or Ca-P complexes, not only may affect the efficacy of phytase, but also the digestibility of P and Ca. Therefore, Ca, P, phytate, and phytase interactions are aspects that need to be considered in Ca digestibility studies.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.60 no.4
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• pp.200-205
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• 2011

In multipath fading channel, diversity is essential to mitigate the impairments. In this paper, we have proposed the angle diversity scheme called ATTD(Angle Time Transmit Diversity) instead of Alamouti's STTD(Space Time Transmit Diversity) and have analyzed the performance of the proposed scheme when signal powers caused by the transmission to different angles are different. Based on it, we have measured the wireless vector-channel in the urban area, which has lots of high-story buildings, using the data collected from the 8 by 4 smart array antenna system that we made. According to the measured data, the received signals from different angles have different signal powers. Our performance analysis results show that the proposed scheme has better performance than the space diversity scheme when the received path signal power is at least -7dB compare to the strongest path signal power.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.8 no.2
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• pp.276-280
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• 2004

본 논문에서는 Matlab Tool을 이용하여 적응변조 OFDM 시스템 GUI 시뮬레이터를 설계하였다. 설계된 시뮬레이터를 이용하여 적응변조 기법을 위한 채널 추정 알고리즘과 무선 채널환경에서 시스템에 미치는 영향을 분석하고 추정된 결과를 이용하여 적응형 등화기를 적용한 적응변조 OFDM 시스템의 성능을 BER과 성좌도를 통하여 분석한다. 분석결과, 기존의 고정된 변조 방식을 사용하는 시스템인 경우 고속의 데이터 전송을 위해 높은 지수의 변조모드(64QAM)를 사용함으로써 채널 환경에 민감하게 심볼오류 발생률이 증가함을 알 수 있었다. 하지만 채널상태에 따라 가변을 취하는 적응변조 OFDM 시스템의 경우 64QAM방식에 비해 (BER=10-2)를 기준으로 약 8㏈ 성능의 이득이 있음을 알 수 있고 적응형 등화기를 적용함에 따라 왜곡을 받은 신호 파형의 보상이 가능함을 알 수 있다. 무수한 장애의 요인을 갖은 무선 채널환경에서 효율적인 데이터 전송을 위해 적응변조시스템이 요구되어짐을 알 수 있었다.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.41 no.7
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• pp.55-61
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• 2004

This paper proposes an antenna selection and switching system between spatial multiplexing and diversity techniques. The proposed system overcomes spatial correlation by using antenna selection method and improve bit error performance with switching encoding nudes between a spatial multipexing encoder and a diversity encoder. Therefore, in a 4 transmit and 2 receive antenna system first, the proposed system selects 2 transmit antennas, and next, switches encoding modes between Space-Time Transmit Diversity and BLAST according to instantaneous channel information. Computer simulations showed that the proposed system improves about 2 or 3 ㏈ SNR in low correlated channel and about 3 ㏈ SNR in highly correlated channel rather than a 2 by 2 antenna switching system.