• Clinical and Experimental Reproductive Medicine
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• 제27권3호
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• pp.283-289
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• 2000

Objective: The study was performed to compare the survival rate and the development of day 2 mouse embryos which had freezing procedures done. Methods: We used three different vitrification solutions (EFS, VS14, DPS) and a ultrarapid freezing solution (UFS) for cryopreservation of day 2 mouse embryo. Results: We tested toxicity by exposing embryos to vitirification solutions and a ultrarapid freezing solution. The survival rates are 100%, 97.8%, 95.6% and 100% (EFS, VS14, DPS and UFS). After cultured for 96 hours, hatching rates of each group are 93.5% (no freezing), 95.6% (EFS), 86.4% (VS14), 93.0% (DPS), and 93.0% (UFS). There is no significant differences among groups. The survival rates after thawing cryopreserved embryos are 80.2%, 91.7%, 69.5%, 0% and 91.8% (slow freezing, EFS, VS14, DPS and UFS). Also cultured for 96 hours, the hatching rates are 93.5% (no freezing), 84.1% (slow freezing), 93.9% (EFS), 48.5% (VS14) and 70.1% (UFS). Conclusion: The survival rates of vitrification in EFS solution and ultrarapid freezing are higher than slow freezing (p<0.05). The hatching rate of vitrification in EFS solution cultured for 96 hours is highest, so vitrification of day 2 mouse embryos in EFS solution considered as more effective for cryopreservation.

• 한국통신학회논문지
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• 제28권3B호
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• pp.191-199
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• 2003

본 논문에서는 무선 ATM망에서 rt_VBR 서비스와 ABR 서비스를 위한 채널 접속제어 알고리즘과 동적 슬롯할당 알고리즘을 제안한다. 제안된 방식에서 실시간 서비스를 요구하는 rt_VBR 단말기는 RAS 미니슬롯을 통하여 예약요청을 하고, 예약에 성공한 단말기는 DPS 미니슬롯을 통하여 경쟁 없이 동적 매개변수를 전송한다. 반면, 비실시간성의 버스트 트래픽을 위한 ABR 단말기는 트래픽 버스트가 발생할 때마다 RAS 미니슬롯을 통하여 경쟁 기반으로 슬롯을 요청한다. 기지국의 스케줄러는 예약에 성공한 rt_VBR 단말기에게 예약요청 시 전송한 요청 슬롯 수와 잔여수명을 기반으로 상향 데이터 슬롯을 할당함과 동시에 DPS 미니슬롯도 할당한다.

• Journal of Power Electronics
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• 제15권1호
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• pp.18-30
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• 2015

This paper focuses on a systematical and in-depth analysis of the reactive power and soft-switching regions of Dual Active Bridge (DAB) converters with dual-phase-shift (DPS) control to achieve high efficiency in a wide operating range. The key features of the DPS operating modes are characterized and verified by analytical calculation and experimental tests. The mathematical expressions of the reactive power are derived and the reductions of the reactive power are illustrated with respect to a wide range of output power and voltage conversion ratios. The ZVS soft-switching boundary of the DPS is presented and one more leg with ZVS capability is achieved compared with the CPS control. With the selection of the optimal operating mode, the optimal phase-shift pair is determined by performance indices, which include the minimum peak or rms inductor current. All of the theoretical analysis and optimizations are verified by experimental tests. The experimental results with the DPS demonstrate the efficiency improvement for different load conditions and voltage conversion ratios.

• Journal of Microbiology and Biotechnology
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• 제16권6호
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• pp.933-938
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• 2006

Decaprenyl diphosphate synthase (DPS) is the key enzyme for the production of coenzyme $Q_{10}$ ($CoQ_{10}$). A dps gene from Sinorhizobium meliioti KCCM 11232 (IFO 14782) was isolated by PCR and then cloned in Escherichia coli. DNA sequencing analysis revealed an open reading frame of 1,017 bp encoding a 338-amino-acid protein. The protein was identical at the 98% level to the putative octaprenyl diphosphate synthase (IspB) of S. meliloti 1021. The deduced amino acid sequence included the DDxxD domains conserved in the majority of the prenyl diphosphate synthases. Heterologous expression in E. coli BL21 (DE3) was carried out, and the $CoQ_{10}$ produced was then analyzed by HPLC. E. coli BL21 (DE3) harboring the dps gene from S. melioti produced CoQ$_{10}$ in addition to endogenous coenzyme Q$_8$ (CoQ$_8$), whereas wild-type E. coli BL21 (DE3) host did not have the ability of producing CoQ$_{10}$. The results suggest that the putative dps from S. meliloti KCTC 2353 encoded the DPS.

• 한국통신학회논문지
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• 제33권12A호
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• pp.1209-1216
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• 2008

무선통신 시스템에 있어서 스펙트럼 효율성과 전송속도의 극대화를 위해 MIMO(Multiple Input Multiple Output) 기술을 시스템에 적용하는 노련이 계속되고 있다. 최근 대두되고 있는 WiMAX와 LTE는 OFDM 기반 기술로서 CDMA보다 MIMO기술을 적용하기 쉽다는 장점에 의해 MIMO 기술을 기본으로 채택하고 있다. 하향 링크에서는 STC(Space Time Coding) 방식과 SM(Spatial Multiplexing) 방식을 사용하여 MIMO 방식을 기본 기술로 적용하였으며 상향링크에서는 C-MIMO(Collaborative MIMO) 기술이 사용된다. 특히, 상향링크는 양방향 데이터 통신을 활용한 다양한 신규 서비스가 제안되고 있어 전송 성능을 개선시킬 수 있는 C-MIMO의 성능향상이 기술 쟁점이 되고 있다. 본 논문에서는 C-MIMO 성능 향상을 위하여 기존에 사용되고 있는 신호간 직교성(OF: Orthogonal Factor)의 성질을 이용하여 단말 조합을 선택하는 방식(DPS: Determinant Pairing Scheduling)과 신호간 직교성을 사용하지 않고 단말 조합을 선택하는 방식(RPS: Random Pairing Scheduling)을 분석하였다. 또한 DPS와 RPS 방식을 보완한 새로운 알고리즘을 제안 하여 스펙트럼 효율을 높이는 방법을 고안하였다. 결과에 의하면 새로운 알고리즘을 통하여 RPS 대비 $2{\sim}3dB$ 이득을 보았으며 DPS에 비하여 현격하게 복잡도를 감소 시켰다.

• 한국항공우주학회지
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• 제40권6호
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• pp.467-474
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• 2012

무인항공기의 정찰 및 정보 수집 능력을 효율적으로 수행하기 위해 장기 체공 능력이 요구된다. 분산 추진 장치는 대형 추진 장치를 복수의 소형 추진 장치들로 대체하여 추력을 얻는 장치이다. 날개의 스팬 길이를 따라 넓게 분포하여 효율이 증가하며, 유동의 흡입을 통해 경계층을 제어하고 출구에서 분사되는 흐름이 항공기에 부착되어 흐르기 때문에 양항비가 증가한다. 본 연구에서는 전익기 융합익기와 분산 추진 장치가 장기 체공 성능을 향상시키는 점에 착안하여 연구를 수행하였다. Eppler 337 에어포일 유닛에 추진 장치의 위치 및 입 출구 가로세로비 변화에 따라 나타나는 공력특성을 분석했다. CFD를 사용하여 공력해석을 수행하였고, 빠른 해석 결과를 얻을 수 있도록 팬 영역에 작동판 이론을 적용하였다. 양항비와 모멘트 비교를 통해 추진 장치의 위치 및 형상을 결정하고자 한다.

• 열처리공학회지
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• 제32권6호
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• pp.249-255
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• 2019

This study is intended to clarify the main microstructural factors that contribute to an increase of hardness during isothermal aging in Mg-Al alloy. For this work, Mg-9.3%Al alloy specimens were solution-treated at 688 K for 24 h followed by water quenching, and then aged at 473 K for up to 24 h. The aging at 473 K yielded nodular discontinuous precipitates (DPs) with (${\alpha}+{\beta}$) lamellar morphology at the grain boundaries, and the volume fraction of DPs increased from 0% to ~30% with increasing aging time up to 12 h. For the aging times longer than 12 h, further formation of DPs was substantially inhibited owing to the occurrence of significant continuous precipitation within the ${\alpha}-(Mg)$ matrix, and the density of continuous precipitates (CPs) becomes greater with increasing aging time. Hardness of the specimen was steadily increased with aging time up to 24 h. Microstructural examination on the aged specimens revealed that the increased overall hardness at the early stage of aging is associated with the increased volume fraction of DPs, but at the later stage of aging, where the amount of DPs was hardly changed, the increased hardness of the ${\alpha}-(Mg)$ matrix in response to the higher density of CPs within the matrix, plays a key role in increasing the overall hardness value.

• 분석과학
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• 제37권2호
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• pp.98-113
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• 2024

The current investigation entails the characterization of five degradation products (DPs) formed under different stress conditions of loteprednol using liquid chromatography-tandem mass spectrometry (LC-MS/MS). In addition, this study developed a stable high-performance liquid chromatography (HPLC) method for evaluating loteprednol along with impurities. The method conditions were meticulously fine-tuned which involved the exploration of the appropriate solvent, pH, flow of the mobile phase, columns, and wavelength. The method conditions were carefully chosen to successfully resolve the impurities of loteprednol and were employed in subsequent validation procedures. The stability profile of loteprednol was exposed to stress degradation experiments conducted under five conditions, and DPs were structurally characterized by employing LC-MS/MS. The chromatographic resolution of loteprednol and its impurities along with DPs was effectively achieved using a Phenomenex Luna 250 mm C18 column using 0.1 % phosphoric acid, methanol, and acetonitrile in 45:25:30 (v/v) pumped isocratically at 0.8 mL/min with 243 nm wavelength. The method produces an accurate fit calibration curve in 50-300 ㎍/mL for loteprednol and LOQ (0.05 ㎍/mL) - 0.30 ㎍/mL for its impurities with acceptable precision, accuracy, and recovery. The stress-induced degradation study revealed the degradation of loteprednol under basic, acidic, and photolytic conditions, resulting in the formation of seven distinct DPs. The efficacy of this method was validated through LC-MS/MS, which allowed for the verification of the chemical structures of the newly generated DPs of loteprednol. This method was appropriate for assessing the impurities of loteprednol and can also be appropriate for structural and quantitative assessment of its degradation products.

• 한국국방경영분석학회지
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• 제17권2호
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• pp.123-134
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• 1991

one of the problems the users of DPS-6/45 used to face in the course of having access to work stations was that a telephone call has to be made manually every time to have receiver's modem on or off, and naturally it meant the waste of manpower as well as of time. A program has been worked out to automatically operate and control. utilizing the system clock within the main computer (DPS-6/45), the on/off switch on the modems. It has resulted in; 1) promotion in operability of the main computer, DPS-6/45 2) prevention of unnecessary telephone calls 3) curtailment of expenditure and manpower

• 한국항해항만학회:학술대회논문집
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• 한국항해항만학회 2015년도 춘계학술대회
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• pp.57-59
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• 2015

심해에서의 유전개발이 활성화되면서 이러한 개발에 필수적인 장비인 동적위치제어시스템 (Dynamic Positioning System, DPS)을 설치한 선박 또는 해양구조물의 수요도 폭발적으로 증가하고 있으며, 이에 따라 DPS 운영에 필수적인 DPO (Dynamic Positioning Operator) 자격증을 취득하고자 하는 지원자도 매년 급속하게 증가하고 있다. 그러나 DPO 교육훈련과정은 강제요건이 아니며, 따라서 엄정한 자격증명 및 검증이 어려운 실정이다. 특히 매년 2000건 이상의 신규면허를 심사하고 발급하는 것은 물론 기존 면허자에 대한 재검증 절차도 수행하여야 하는 현재의 상황으로 볼 때 효율적인 DPO 양성을 기대하기는 어려운 실정이다. 이 연구에서는 보다 이러한 문제점을 개선하여 보다 더 효율적이면서도 엄정한 DPO 양성을 위한 제도개선을 제안한다.