• 대한수학회보
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• 제54권2호
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• pp.359-373
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• 2017

In this paper, we propose the Stancu type generalization of a kind of modified q-Gamma operators. We estimate the moments of these operators and give the basic convergence theorem. We also obtain the Voronovskaja type theorem. Furthermore, we obtain the local approximation, rate of convergence and weighted approximation for these operators.

• 한국안전학회지
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• 제5권3호
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• pp.27-32
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• 1990

Standardization of solar collector test method is desirable for improvement solar collector quality and Valuation of collector thermal performance. In the present work, test loop proposed by Chun, is modified for convenience of test and obtained accurate collector thermal performance. An experimental investigation hat been carried out with a modified collector test loop under a real sun condition in order to confirm the utility of modified test loop and study the effect of variation of flow rate on thermal efficiency, the range of optimum flow rate and critical incident angle.

• Korean Journal of Radiology
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• 제22권9호
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• pp.1579-1586
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• 2021

Objective: To evaluate the diagnostic performance of the modified Korean Thyroid Imaging Reporting and Data System (K-TIRADS), and compare it with the 2016 version of K-TIRADS using the Thyroid Imaging Network of Korea. Materials and Methods: Between June and September 2015, 5708 thyroid nodules (≥ 1.0 cm) from 5081 consecutive patients who had undergone thyroid ultrasonography at 26 institutions were retrospectively evaluated. We used a biopsy size threshold of 2 cm for K-TIRADS 3 and 1 cm for K-TIRADS 4 (modified K-TIRADS 1) or 1.5 cm for K-TIRADS 4 (modified K-TIRADS 3). The modified K-TIRADS 2 subcategorized the K-TIRADS 4 into 4A and 4B, and the cutoff sizes for the biopsies were defined as 1 cm for K-TIRADS 4B and 1.5 cm for K-TIRADS 4A. The diagnostic performance and the rate of unnecessary biopsies of the modified K-TIRADS for detecting malignancy were compared with those of the 2016 K-TIRAD, which were stratified by nodule size (with a threshold of 2 cm). Results: A total of 1111 malignant nodules and 4597 benign nodules were included. The sensitivity, specificity, and unnecessary biopsy rate of the benign nodules were 94.9%, 24.4%, and 60.9% for the 2016 K-TIRADS; 91.0%, 39.7%, and 48.6% for the modified K-TIRADS 1; 84.9%, 45.9%, and 43.5% for the modified K-TIRADS 2; and 76.1%, 50.2%, and 40.1% for the modified K-TIRADS 3. For small nodules (1-2 cm), the diagnostic sensitivity of the modified K-TIRADS decreased by 5.2-25.6% and the rate of unnecessary biopsies reduced by 19.2-32.8% compared with those of the 2016 K-TIRADS (p < 0.001). For large nodules (> 2 cm), the modified K-TIRADSs maintained a very high sensitivity for detecting malignancy (98%). Conclusion: The modified K-TIRADSs significantly reduced the rate of unnecessary biopsies for small (1-2 cm) nodules while maintaining a very high sensitivity for malignancy for large (> 2 cm) nodules.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 1999년도 학회창립 10주년 기념 1999년도 가을 학술발표회 논문집
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• pp.155-158
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• 1999

This paper discusses the validity of models to predict the compressive strength of concrete subjected to various temperature histories and the shortcomings of existing rate constant model and apparent activation energy concept. Based on the discussion, a modified rate constant model is proposed. The modified rate constant model, in which apparent activation energy is a nonlinear function of curing temperature and age, accurately estimates the development of the experimental compressive strengths by a few researches. Also, the apparent activation energy of concrete cured with high temperature decreases rapidly with age, but that cured with low temperature decreases gradually with age. Finally a generalized model to predict apparent activation energy and compressive strength is proposed, which is based on the regression results.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2014년도 추계 학술논문 발표대회
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• pp.21-22
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• 2014

The purpose of this study is to ascertain strengths and hardening rate of epoxy-modified mortar with wood-tar contents. The polymer-modified mortars (PMMs) using epoxy resin with wood-tar are prepared with various polymer-binder ratios of 1, 3, 5% and wood-tar contents of 0, 5, 10, 15 and 20%. The PMMs using epoxy resin are tested for compressive, flexural and tensile strengths and hardening rate of epoxy resin. As a result, the strengths and hardening rate under polymer-binder ratio 1% and wood-tar content of 5% are more excellent than those of other specimens.

• 산업기술연구
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• 제20권A호
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• pp.179-184
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• 2000

The surface of porous alumina membrane was modified with silane coupling agent in order to enhance hydrophobicity. The contact angle of water to the surface-modified alumina membrane was greater than $90^{\circ}$. The surface-modified membrane was tested in vapor permeation for the concentration of aqueous ethanol. With the increase of ethanol concentration in the feed, permeation flux increased due to the greater affinity of ethanol with surface-modified alumina membrane than that of water. The experimental results showed that the permeation rate of surface-modified alumina membrane was 15~1000 times greater than that of polymer membranes.

• ETRI Journal
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• 제29권2호
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• pp.143-152
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• 2007

In this paper, we propose a time-varying modified minimum mean-squared error (MMSE) detector for the detection of higher data rate signals in a multirate asynchronous code-division multiple-access (CDMA) system which is signaled in a fast Rayleigh fading channel. The interference viewed by a higher data rate symbol will be periodic due to the presence of a lower data rate symbol which spans multiple higher data rate symbols. The detection is carried out on the basis of a modified MMSE criterion which incorporates differential detection and the ratio of channel coefficients in two consecutive observation intervals inherently compensating the fast variation of the channel due to fading. The numerical results obtained by the MMSE detector with time-varying detection show around 3 dB (M=2) and 6 dB (M=4) performance improvement at a BER of $10^{-3}$ in the AWGN channel, while introducing more computational complexity than the MMSE detector without time-varying detection. At a higher $E_b/N_0$, the proposed scheme can achieve a BER of approximately $10^{-3}$ in the presence of fast channel variation which is an improvement over other schemes.

• 한국지반공학회논문집
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• 제26권1호
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• pp.55-62
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• 2010

진동타입기에 의해 시공되는 강널말뚝의 관입속도를 예측하고자 수정 Ramberg-Osgood 모델을 적용하여 진동타입기의 주기운동에 따른 지반의 동적 저항력을 모사하고자 하였다. 수정 Ramberg-Osgood 모델을 규정짓는 다양한 인자는 현장시험을 통해 구한 동적 지반저항력곡선의 양상을 반영하여 결정하였는데 이때 매개변수로는 표준관입시험값(N값)을 이용하였다. 관입속도는 해석결과가 현장시험결과에 비해 작게 계산되었으며 관입깊이에 따른 관입 소요시간은 해석결과가 현장시험결과에 비해 크게 계산되어 해석결과가 현장시험결과에 비해 보수적인 값을 보여주었다.

• 한국가축번식학회지
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• 제10권2호
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• pp.204-210
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• 1986

As a part of in vitro fertilization(IVF) for farm animals, IVF experiment was conducted using New Zealand white rabbits with their sperm capacitated in vivo. The effect of uterine conditions on sperm capacitation and effect of sperm concentration and fertilization media on IVF rate and implantation of in vitro fertilized ova were studied. The results obtained are summarized as follows; 1. Acrosomal reaction, noted after staining, of sperm recovered from ligated and intact uterus of capacitators was 83.0% and 65.7%, respectively. 2. IVF rate of ova inseminated with sperm from ligated uterus tended to be higher in DM or with higher concentration of sperm than in the modified F12 medium or with lower sperm concentration. Cleavage rate of fertilized ova for 48hr in DM was 31.5% for 106/ml and 30.0% for 104/ml of sperm and that in modified F12 medium was 26.0% for 106/ml and 22.3% for 104/ml of sperm. 3. Using the sperm from intact uterus, cleavage rate of fertilized ova showed same tendency as those shown with ligated uterus. The rate was 82.0% for 106/ml and 66.5% for 104/ml of sperm in DM and was 69.0% for 106/ml and 56.5% for 104/ml of sperm in the medium. 4. When normal ova up to 48hr after IVF were cultured for 4 days in either DM or modified F12 medium, ova developed to blastocyst stage showed higher rate in the groups of higher sperm concentration in the both media. The rate was 80.9% and 60.0% for 106/ml and 104/ml of sperm in DM and 91.7% and 71.4% for 106/ml and 104/ml of sperm in the modified F12 medium, respectively. 5. Rate of implantation after transfer of 4- or 8-cell embryos was 36.8%.

• 한국환경과학회지
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• 제32권1호
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• pp.57-65
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• 2023

The advanced oxidation treatment using persulfate and zero-valent iron (ZVI) has been evaluated as a very effective technology for remediation of soil and groundwater contamination. However, the high rate of the initial reaction of persulfate with ZVI causes over-consumption of an injected persulfate, and the excessively generated active species show a low transfer rate to the target pollutant. In this study, ZVI was modified using selenium with very low reactivity in the water environment with the aim of controlling the persulfate activation rate by controlling the reactivity of ZVI. Selenium-modified ZVI (Se/ZVI) was confirmed to have a selenium coating on the surface through SEM/EDS analysis, and low reductive reactivity to trichlroethylene (TCE) was observed. As a result of inducing the persulfate activation using the synthesized Se/ZVI, the persulfated consumption rate was greatly reduced, and the decomposition rate of the model contaminant, anisole, was also reduced in proportion. However, the final decomposition efficiency was rather increased, which seems to be the result of preventing persulfate over-consumption. This is because the transfer efficiency of the active species (SO4-∙) of persulfate to the target contaminant has been improved. Selenium on the surface of Se/ZVI was not significantly dissolved even under oxidation conditions by persulfate, and most of it was present in the form of Se/ZVI. It was confirmed that the persulfate activation rate could be controlled by controlling the reactivity of ZVI, which could greatly contribute to the improvement of the persulfate oxidation efficiency.