• KSII Transactions on Internet and Information Systems (TIIS)
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• 제13권3호
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• pp.1311-1324
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• 2019

In the traditional cellular network communication, the cellular user and the base station exchange information through the uplink channel and downlink channel. Meanwhile, device-to-device (D2D) users access the cellular network by reusing the channel resources of the cellular users. However, when cellular user channel conditions are poor, not only D2D user cannot reuse its channel resources to access the network, but also cellular user's communication needs cannot be met. To solve this problem, we introduced a novelty D2D communication mechanism in the downlink, which D2D transmitter users as half-duplex (HD) relays to assist the downlink transmission of cellular users with reusing corresponding spectrum. The optimization goal of the system is to make the cellular users in the bad channel state meet the minimum transmission rate requirement and at the same time maximize the throughput of the D2D users. In addition, i for the purpose of improving the efficiency of relay transmission, we use two-antenna architecture of D2D relay to enable receive and transmit signals at the same time. Then we optimized power of base station and D2D relay separately with consideration of backhaul interference caused by two-antenna architectures. The simulation results show that the proposed HD relay strategyis superior to existing HD and full-duplex (FD) models in the aspects of system throughput and power efficiency.

• 대한화학회지
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• 제41권12호
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• pp.645-652
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• 1997

클로로착물 Cp*Ru(CO)(PR3)H (Cp*=η5-C5Me5, PR3=PMe3, PEt3, PMePh2, PPh3, PCy3)을 출발물질로 사용하여 다양한 히드리드화시약(NaBH4, LiAlH4, LiBEt3H)이나 NaOMe를 반응시켜서 대응하는 히드리드착물 Cp*Ru(CO)(PCy3)H(5)를 합성하였다. Cp*Ru(CO)(PCy3)H(5)착물의 C6D6ㅇ용액에 UV를 조사하면 분자간 및 분자내 C-H결합 활성화반응을 통하여 용매의 중수소와 착물의 배위 리간드인 Cp*, PCy3, Ru-H의 수소 사이에 H/D 교환반응이 진행되었으며 그 반응기구를 설명하였다.

• 음성과학
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• 제14권2호
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• pp.23-33
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• 2007

This study examined the aerodynamic functions (mean airflow rate MFR, subglottal pressure Psub) and closed quotients (CQs) in the fixed pitch (C3, E3, G3, C4) with the variable loudness (70 and 80 dB) as well as in the fixed loudness at 70 dB and 80 dB with the variable pitch (C3, E3, G3, C4) in five classic male singers (Baritone). Results showed that MFR significantly increased at C3, E3, and G3 and Psub significantly increased at C4 when the loudness increased from 70 to 80 dB. At 70 dB, MFR and Psub significantly increased and CQ significantly decreased when the pitch increased from C3 to C4. At 80 dB, MFR significantly decreased when the pitch increased from C3 to G3. However, Psub showed the significant decrease with the pitch increased at 80 dB. In conclusion, as the loudness increases, the aerodynamic loss is getting higher and vocal efficiency becomes lower at low pitch than at higher pitch. At a low loudness level, the main mechanism to control loudness is the amount of medial compression of the vocal folds rather than the aerodynamic function. In addition, the aerodynamic function and medial compression of the vocal folds have a significant role in increasing the loudness level.

• 한국가스학회지
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• 제2권3호
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• pp.18-24
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• 1998

본 연구에서는 한계비용 이론에 바탕을 둔 램지가격결정방식과 효율적요소가격결정방식을 이용하여 천연가스 가격체계의 이론적 모형을 도출함으로써 사회후생의 최적화를 달성하기 위한 국내 가스가격결정방식의 개선방향을 제시하였다. 사례연구를 통하여 국내 가스산업의 현행 원가보상방식, 램지가격결정방식과 효율적요소가격결정방식에 의한 가격간에 배분효율성과 사회후생을 비교 분석하였다. 배분효율성은 도시가스용의 경우에 원가보상방식이 램지가격결정방식 및 효율적요소가격결정방식에 비하여 높게 나타났으나, 발전용의 경우는 원가보상방식이 두 방식에 비하여 낮음을 알 수 있었다. 반면에 사회후생효과는 현행의 원가보상에 의한 가격결정방식보다 램지가격결정방식과 효율적요소가격결정방식을 적용하는 것이 보다 더 향상되는 것으로 나타났다.

• 대한조선학회논문집
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• 제57권5호
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• pp.287-296
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• 2020

The present study aims to improve the accuracy of the maneuvering simulations based on captive model test results. To derive the hydrodynamic coefficients in a self-propelled condition, a mathematical maneuvering model using a whole vehicle model was established. Captive model tests were carried out using the Vertical Planar Motion Mechanism (VPMM) equipment. A motor controller was used to control the constant propeller revolution rate during pure motion tests. The resistance tests, self-propulsion tests, static drift tests, and VPMM tests were performed in the towing tank of Seoul National University. When the vertical drift angle changes, the gravity load on the sensors were changed. The hydrodynamic forces were deduced by subtracting the gravity load from the measured forces. The hydrodynamic coefficients were calculated using the least-square method. The simulation of the turning circle test was compared with the free-running model test result, and the error of the turning radius was 8.3 % compared to the free-running model test.

• 한국자동차공학회논문집
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• 제24권5호
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• pp.527-537
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• 2016

Recent automakers are trying to be more precise with the dimension check and moving parts to guarantee high quality and satisfy customer requirements. The aim of this paper is to investigate the design tolerance suitability of door operating mechanism linked arms, lever, and cam-shaft in a mobile air handling unit. These parts are complicated because doors, arms, lever and cam-shaft are connected nonlinearly in 3D. The current tolerance analysis method poses problems in design analysis because the moving doors are reasonably suitable for the AHU function. The 3-DCS analysis method provided useful results not only in establishing the inspection criteria for the quality control of products but also in enabling economical production. As a result, the vent door had $1.62^{\circ}{\sim}1.72^{\circ}$ and the defrost door had $0.84^{\circ}{\sim}0.9^{\circ}$ for the directly connected arms operating-type. For the lever connected arm operating-type, the foot door had $2.0^{\circ}{\sim}2.24^{\circ}$ tolerance, while the tolerance values satisfied the air flow volume distribution rate criteria in the AHU. Finally, the results have confirmed the design's tolerance suitability by using 3-DCS analysis at the early design stages. Reliability can be achieved by analyzing accumulated tolerance during the sub-parts assembly process and the moving mechanism linked especially by arms, lever, and cam-shaft.

• Biomolecules & Therapeutics
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• 제10권1호
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• pp.50-58
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• 2002

lt had been reproted previously that (${\pm}$)6-chloro-7,8-dihydroxy-1-phenyl 2,3,4,5-tetra-hydro -lH-3benzazepine (SKF 81297), dopamine $D_1$ receptor agonist, produced diuresis by both Indirect action through central function and direct action being induced in kidney. This study was attempted in order to examine the diuresis mechanism of such SKF 81297 Diuretic action of SKF 81297 given into the vein or the carotid artery was not affected by renal denervation, whereas diuretic action of SKF 81297 administered into a renal artery was blocked completely by renal denervation, and then diuretic action of SKF 81297 injected into carotid artery was inhibited by SCH 23390, dopamine $D_1$ receptor antagonist, given into carotid artery. Above results suggest that indirect diuretic action of SKF 81297 elicites through central dopamine $D_1$ receptor and direct diuresis in kidney by influence of renal nerves.

• The Korean Journal of Physiology and Pharmacology
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• 제28권3호
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• pp.265-273
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• 2024

This study aims to explore possible effect of RNA polymerase I subunit D (POLR1D) on proliferation and angiogenesis ability of colorectal cancer (CRC) cells and mechanism herein. The correlation of POLR1D and Yin Yang 1 (YY1) expressions with prognosis of CRC patients in TCGA database was analyzed. Quantitative realtime polymerase chain reaction (qRT-PCR) and Western blot were applied to detect expression levels of POLR1D and YY1 in CRC cell lines and CRC tissues. SW480 and HT-29 cells were transfected with si-POLR1D or pcDNA3.1-POLR1D to achieve POLR1D suppression or overexpression before cell migration, angiogenesis of human umbilical vein endothelial cells were assessed. Western blot was used to detect expressions of p38 MAPK signal pathway related proteins and interaction of YY1 with POLR1D was confirmed by dual luciferase reporter gene assay and chromatin immunoprecipitation (ChIP). TCGA data showed that both POLR1D and YY1 expressions were up-regulated in CRC patients. High expression of POLR1D was associated with poor prognosis of CRC patients. The results showed that POLR1D and YY1 were highly expressed in CRC cell lines. Inhibition or overexpression of POLR1D can respectively suppress or enhance proliferation and angiogenesis of CRC cells. YY1 inhibition can suppress CRC progression and deactivate p38 MAPK signal pathway, which can be counteracted by POLR1D overexpression. JASPAR predicted YY1 can bind with POLR1D promoter, which was confirmed by dual luciferase reporter gene assay and ChIP. YY1 transcription can up-regulate POLR1D expression to activate p38 MAPK signal pathway, thus promoting proliferation and angiogenesis ability of CRC cells.

• 한국세라믹학회지
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• 제53권3호
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• pp.349-353
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• 2016

We prepared a number of reaction-bonded silicon carbides (RBSCs) made from various mixing ratios of raw SiC particles, and investigated their microstructure and etch characteristics by Reactive Ion Etch (RIE). Increasing the amount of $9.5{\mu}m$-SiC particles results in a microstructure with relatively coarser Si regions. On the other hand, increasing that of $2.6{\mu}m$-SiC particles produces much finer Si regions. The addition of more than 50 wt% of $2.6{\mu}m$-SiC particles, however, causes the microstructure to become partially coarse. We also evaluated their etching behaviors in terms of surface roughness (Ra), density and weight changes, and microstructure development by employing Confocal Laser Scanning Microscope (CLSM) and Scanning Electron Microscope (SEM) techniques. During the etching process of the prepared samples, we confirmed that the residual Si region was rapidly removed and formed pits isolating SiC particles as islands. This leads to more intensified ion field on the SiC islands, and causes physical corrosion on them. Increased addition of $2.6{\mu}m$-SiC particles produces finer residual Si region, and thus decreases the surface roughness (Ra.) as well as causing weight loss after etching process by following the above etching mechanism.

• 대한기계학회논문집B
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• 제29권9호
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• pp.997-1005
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• 2005

The extinction characteristics of low strain rate normal gravity (1-g) nonpremixed methane-air flames were studied numerically and experimentally. A time-dependent axisymmetric two-dimensional (2D) model considering buoyancy effects and radiative heat transfer was developed to capture the structure and extinction limits of 1-g flames. One-dimensional (1D) computations were also conducted to provide information on 0-g flames. A 3-step global reaction mechanism was used in both the 1D and 2D computations to predict the measured extinction limit and flame temperature. A specific maximum heat release rate was introduced to quantify the local flame strength and to elucidate the extinction mechanism. Overall fractional contribution by each term in the energy equation to the heat release was evaluated to investigate the multi-dimensional structure and radiative extinction of 1-g flames. Images of flames were taken for comparison with the model calculation undergoing extinction. The two-dimensional numerical model was validated by comparing flame temperature profiles and extinction limits with experiments and ID computation results. The 2D computations yielded insight into the extinction mode and flame structure of 1-g flames. Two combustion regimes depending on the extinction mode were identified. Lateral heat loss effects and multi-dimensional flame structure were also found. At low strain rates of 1-g flame ('Regime A'), the flame is extinguished from the weak outer flame edge, which is attributed to multi-dimensional flame structure and flow field. At high strain rates, ('Regime B'), the flame extinction initiates near the flame centerline due to an increased diluent concentration in reaction zone, which is the same as the extinction mode of 1D flame. These two extinction modes could be clearly explained with the specific maximum heat release rate.