• KSII Transactions on Internet and Information Systems (TIIS)
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• 제9권6호
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• pp.2271-2288
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• 2015

The emerging high efficiency video coding (HEVC) standard adopts the quadtree-structured transform unit (TU) in the residual quadtree (RQT) coding. Each TU allows to be split into four equal sub-TUs recursively. The RQT coding is performed for all the possible transform depth levels to achieve the highest coding efficiency, but it requires a very high computational complexity for HEVC encoders. In order to reduce the computational complexity requested by the RQT coding, in this paper, we propose a fast TU size decision method incorporating an adaptive maximum transform depth determination (AMTD) algorithm and a full check skipping - early termination (FCS-ET) algorithm. Because the optimal transform depth level is highly content-dependent, it is not necessary to perform the RQT coding at all transform depth levels. By the AMTD algorithm, the maximum transform depth level is determined for current treeblock to skip those transform depth levels rarely used by its spatially adjacent treeblocks. Additionally, the FCS-ET algorithm is introduced to exploit the correlations of transform depth level between four sub-CUs generated by one coding unit (CU) quadtree partitioning. Experimental results demonstrate that the proposed overall algorithm significantly reduces on average 21% computational complexity while maintaining almost the same rate distortion (RD) performance as the HEVC test model reference software, HM 13.0.

• 한국인터넷방송통신학회논문지
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• 제18권2호
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• pp.111-116
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• 2018

본 논문은 Multilevel QAM 신호의 전송시 채널에서 발생되는 부호간 간섭을 최소화시키기 위한 RMMA (Region-based MMA)와 SCA (Square Contour Algorithm) 적응 등화 알고리즘의 성능 비교에 관한 것이다. RMMA는 Multilevel QAM 신호의 등화시 기존 MMA 알고리즘에서 안정성과 4-level의 constant modulus로 변환하여 성능을 개선키 위하여 사용되며, SCA는 기존 CMA와 RCA을 조합하여 등화 성능을 개선키 위하여 사용된다. 이들은 서로 상이한 원리를 적용하여 등화 성능을 개선하고 있으므로, 논문에서는 이들의 성능을 동일한 채널 환경에 적용하여 비교하였다. 이를 위한 성능 지수로는 등화기 출력 성상도, 잔류 isi, 최대 찌그러짐을 적용하였다. 컴퓨터 시뮬레이션 결과 모든 성능에서는 RMMA가 SCA보다 신호점 군집 능력과 수렴 속도에서 우월하며, misadjustment에 의한 등화 잡음이 감소함을 알 수 있었다.

• Food Science and Biotechnology
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• 제18권4호
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• pp.939-947
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• 2009

In order to produce vinegar using onions, 12 acetic acid bacteria were screened from the juice of fallen peaches, and a strain showing the highest acetic acid productivity among them was selected and identified as Acetobacter tropicalis No. 22. The culture broth containing 2.5%(w/v) of initial sugar concentration showed maximum acetic production after 10 days of cultivation, and the acetic acid was produced at the highest rate and reached the maximum acidity after 2 to 6 days of cultivation when the residual sugar and the ethanol concentration were in the range of 1.6 to 2%(w/v) and 0.6 to 1.8%(v/v), respectively. Also optimum conditions for acetic acid production by response surface method using the fractional factorial design with 3 variables and 5 levels were involved with initial ethanol content of 4.67%(v/v), initial acidity of 0.03%, and initial glucose concentration of 2.35%(w/v) and predicted level of acetic acid production at these conditions was 3.77%.

• Advances in concrete construction
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• 제7권1호
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• pp.31-37
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• 2019

This paper evaluates the workability and hardened properties of self-compacting concrete (SCC) containing silica fume as the partial replacement of cement. SCC mixtures with 0, 2, 4, 6, 8 and 10% silica fume were tested for fresh and hardened properties. Slump flow with $T_{500}$ time, L-box and V-funnel tests were performed for evaluating the workability properties of SCC mixtures. Compressive strength, splitting tensile strength and modulus of rupture were performed on hardened SCC mixtures. Experiments revealed that replacement of cement by silica fume equal to and more than 4% reduced the slump flow diameter and increased the $T_{500}$ and V-funnel time linearly. Compressive strength, splitting tensile strength and modulus of rupture increased with increasing the replacement level of cement by silica fume and were found to be maximum for SCC mixture with 10% silica fume. Further, residual hardened properties of SCC mixture yielding maximum strengths (i.e., SCC with 10% silica fume) were determined experimentally after heating the concrete samples up to 200, 400, 600 and $800^{\circ}C$. Reductions in hardened properties up to $200^{\circ}C$ were found to be very close to normal vibrated concrete (NVC). For 400 and $600^{\circ}C$ reductions in hardened properties of SCC were found to be more than NVC of the same strength. Explosive spalling occurred in concrete specimens before reaching $800^{\circ}C$.

• Steel and Composite Structures
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• 제49권3호
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• pp.257-270
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• 2023

In this study, the feasibility and applicability of a friction damper with a vertical installation scheme are investigated. This device is composed of a steel section and two friction hinges at both ends which dissipate seismic energy. Due to its small width and vertical installation scheme, the proposed damper can minimize the interference with architectural functions. To evaluate the performance of the proposed damper, its mechanical behavior is theoretically evaluated and the required formulas for the yield strength and elastic stiffness are derived. The theoretical formulas are verified by establishing the analytical model of the damper in the SAP2000 software and comparing their results. To further investigate the performance of the developed damper, the provided analytical model is applied to a 4-story reinforced concrete (RC) structure and its performance is evaluated before and after retrofit under the Maximum Considered Earthquake (MCE) hazard level. The seismic performance is thoroughly evaluated in terms of maximum interstory drift ratio, displacement time history, residual displacement, and energy dissipation. The results show that the proposed damper can be efficiently used to protect the structure against seismic loads.

• Steel and Composite Structures
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• 제16권6호
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• pp.595-609
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• 2014

The paper is reporting some comparisons between experimental and numerical results in terms of failure mode, failure time and ballistic properties of mild steel sheet. Several projectile shapes have been considered to take into account the stress triaxiality effect on the failure mode during impact, penetration and perforation. The initial and residual velocities as well as the failure time have been measured during the tests to estimate more physical quantities. It has to be noticed that the failure time was defined using a High Speed Camera (HSC). Thanks to it, the impact forces (average and maximum level), were analyzed using numerical simulations together with an analytical description coupled to experimental observations. The key point of the model is the consideration of a shape function to define the pulse loading during perforation.

• Journal of Electrical Engineering and Technology
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• 제13권3호
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• pp.1052-1059
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• 2018

This paper deals with commutation failure of the line-commutated converter high voltage direct current (LCC HVDC) system caused by a three phase fault in the ac power system. An analytic calculation method is proposed to estimate the maximum permissible voltage drop at the LCC HVDC station on various operating point and to assess the area of vulnerability for commutation failure (AOV-CF) in the power system based on the residual phase voltage equation. The concept is extended to multi-infeed HVDC power system as the area of severity for simultaneous commutation failure (AOS-CF). In addition, this paper presents the implementation of a shunt compensator applying to the proposed method. An analysis and simulation have been performed with the IEEE 57 bus sample power system and the Jeju island power system in Korea.

• International Journal of Internet, Broadcasting and Communication
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• 제11권4호
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• pp.43-48
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• 2019

We design a reconfigurable optical node for metropolitan WDM networks, and numerically study the capability of the node in the optical signal level. Unlike a long-haul WDM system, major limitations of metropolitan WDM systems are power loss, fiber dispersion and optical signal-to-noise ratio(OSNR) degradation due to EDFAs. Therefore, we include the behaviors of transmitter and receiver, and fiber, EDFAs, and optical filters(MUX/DeMux) in numerical simulations with varying parameters over wide range. From simulation results, we can identify the maximum span numbers for OC-48 and OC-192 to achieve $BER<10^{-12}$ using the node structure at various received powers and residual dispersions.

• Journal of Applied Biological Chemistry
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• 제56권1호
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• pp.29-35
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• 2013

This study was performed to analyze 48 kinds of pesticide residues using gas chromatography (GC)/nitrogen phosphorous detector, GC/micro electron capture detector, GC/mass selective detector, and high performance liquid chromatograph/diode array detector in 186 fresh ginseng samples collected in the Seoul area from 2010 to 2011. Fresh ginseng dietary intakes were estimated using the data from the 2009 Korea National Health and Nutrition examination survey. Residual pesticides were detected in 79 samples (42.5%) with eight different fungicides. Only 20 samples (10.8%) exceeded the maximum residue limits (MRLs) for pesticides registered by the Korea Food & Drug Administration. Among them, tolclofos-methyl residues (10.2%) exceeded the MRL for fresh ginseng in 18 ginseng seedlings and one of the two-year old fresh ginseng plants, and the residual level in just one ginseng seedling violated the MRL for pyrimethanil. The results showed that residual pesticides levels in marketable fresh ginseng around Seoul were relatively safe. The percent acceptable daily intake (%ADI) was calculated using pesticide residues in fresh ginseng and dietary intakes of fresh ginseng. The risk caused by pesticide residues in fresh ginseng was very low.

• 한국식품영양과학회지
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• 제44권7호
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• pp.1035-1040
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• 2015

껍질을 제거하지 않은 새우의 경우 10일 동안 저장하는 과정에서 갈변이 심각하게 진행된 것을 확인할 수 있었다. 갈변은 두흉부, 등껍질 그리고 꼬리 순서로 진행되었으며, 4-hexylresorcinol 침지액에 의해 갈변이 억제될 경우 꼬리, 등껍질 그리고 두흉부 순서로 억제되었다. 껍질을 제거하지 않은 새우의 경우 10, 20 mg/L 4-hexylresorcinol 침지액 농도에서 72시간 침지한 새우로부터 각각 1.36, 2.33 mg/kg의 잔류농도를 확인하였으며, 해외에서 규정하고 있는 최대잔류수준 이상의 4-hexylresorcinol이 검출되어 갈변억제 효과는 있었지만 사용방법으로 부적합한 것으로 나타났다. 껍질을 제거한 새우의 경우에는 가식부위가 직접 침지액에 침지되기 때문에 대부분의 새우에서 1 mg/kg 이상의 4-hexylresorcinol 잔류량이 확인되었으며, 껍질을 제거한 새우를 20 mg/L 4-hexylresorcinol 침지액에 72시간 동안 침지한 처리군에서 13.46 mg/kg으로 가장 높은 4-hexylresorcinol 잔류량이 확인되었다. 이러한 결과는 캐나다 및 중국뿐만 아니라 유럽에서 규정하고 있는 최대잔류수준을 초과함에 따라서 새우의 침지 조건으로 새우 껍질을 제거한 뒤 침지하는 방법은 적합하지 않은 것으로 판단되며, 갈변억제 효과는 20 mg/L 4-hexylresorcinol 침지액에서 24시간 동안 침지한 처리군에서 가장 높은 억제 효과를 나타내었다. 본 연구 결과 4-hexylresorcinol 침지액 농도와 침지 시간에 따라 4-hexylresorcinol 잔류량 및 갈변억제 효과에 높은 상관관계를 나타내었으며, 규정에 제시되어 있는 최대잔류허용량을 초과하지 않고 효율적인 갈변억제 효과를 얻기 위한 방법으로는 껍질을 제거하지 않은 새우에서 20 mg/L 4-hexylresorcinol 침지액에서 24시간 동안 침지처리하는 방법이 가장 적절한 것으로 확인되었다.