• Applied Chemistry for Engineering
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• v.8 no.2
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• pp.308-314
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• 1997

The effects of catalyst and blocking reagents(BR) on the blocking reactions of TDI and MDI in the preparation of polyurethane varnishes have been studied. It was found that certain types of catalysts, such as 1,4-diazabicyclo[2.2.2]octane(DABCO) and tetramethyl guanidine(TMG), were necessary to complete the NCO blocking reactions. Blocking rate of TMG was shown much faster than that of DABCO. Reactivity increased with the increase of TMG concentration, at least to the concentration of 1%. In case of DABCO, the 0.25% concentration of catalyst showed the highest reactivity. In order to study the steric effects of BR on the blocking reactions, phenol, p-cresol, m-cresol, o-cresol, 2,4-xylenol were used as blocking reagents. As expected, BR which has less steric hindrance showed higher reactivity. The increase in BR concentration and reaction temperature increased the productivity of polyurethanes in this reaction system.

• Atmosphere
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• v.33 no.1
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• pp.49-59
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• 2023

Blocking refers to a class of weather phenomena appearing in the mid and high latitudes, whose characteristics are blocked airflow of persistence. Frequently found over the Pacific and Atlantic regions of the Northern Hemisphere, blocking affects severe weather in the surrounding areas with different mechanisms depending on the type of blocking patterns. Along with lots of studies about persistent weather extremes focusing on the specific types of blocking, a new categorization using Rossby wave breaking has emerged. This study aims to apply this concept to the classification of blockings over the Pacific and examine how different wave breakings specify the associated cold weather in the Korean peninsula. At the same time, we investigate a strongly developing ridge around the Pacific by designing a new detection algorithm, where a reversal method is modified to distinguish ridge-type blocking patterns. As result, Kamchatka blocking (KB) and strong ridge over the Central Pacific are observed the most frequently during 20 years (2001~2020) of the studied period, and anomalous low pressures with cold air over the Korean Peninsula are accompanied by blocking events. When it considers the Rossby wave breaking, cyclonic wave-breaking is dominant in KB, which generates low-pressure anomalies over the Korean Peninsula. However, KB with anticyclone wave breaking appears with the high-pressure anomalies over the Korean Peninsula and it generates the warm temperature anomaly. Lastly, the low-pressure anomalies are also generated by the strong ridge over the Central Pacific, which persists for approximately three days and give a significant impact on cold surge on the Korean Peninsula.

• ETRI Journal
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• v.10 no.4
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• pp.127-139
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• 1988

전전자교환기에서 가장 많이 이용되고 있는 T-S-T three-stage 스위치 네트워크의 blocking 확률에 대한 대표적인 세가지 모형에 대해 살펴보고 스위치 네트워크의 구조 또는 통화로 탐색수에 따라 그 적용이 제한된 blocking 확률식에 대해 일반적으로 적용할 수 있는 확장된 표현식으로 유도하여 보았으며 각각에 대한 비교분석을 수행하였다. 또한 blocking 확률에 따른 three-stage 스위치 네트워크의 통화처리용량을 산출하는 방법을 설명하고 수리적인 예로서 위에서 제안된 blocking 확률모형들을 이용하여 TDX-1B 스위치 네트워크의 통화처리용량을 산출하여 보았다. 끝으로 T-S-T three-stage 스위치 네트워크에서의 blocking 확률모형들에 대한 전반적인 검토와 함께 blocking 확률을 줄일 수 있는 방법을 제안하였다.

• Proceedings of the Korean Society for Language and Information Conference
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• 2007.11a
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• pp.275-284
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• 2007

Among the languages that allow long-distance reflexives, some languages have blocking effects, whereas others don't. The goal of this paper is to provide computational algorithms that can handle presence and absence of blocking effects of long-distance reflexives. We will examine the blocking effects in Chinese and Korea and develop computational algorithms for handling blocking effects in those two languages. The algorithms will be developed by incorporating Chierchia's Binding Theory into Steedman's Combinatory Categorial Grammar (CCG). Through the analyses and implementations, this paper illustrates how blocking effects can be implemented computationally.

• Transactions on Electrical and Electronic Materials
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• v.1 no.4
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• pp.16-19
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• 2000

Power transistors to be used in Power Integrated Circuits(PIC) are required to have low on resistance, fast switching speed, and high breakdown voltage. The lateral IGBTs(LIGBTs)are promising power devices for high voltage PIC applications, because of its superior device characteristics. In this paper, dual cathode LIGBT(DCIGBT) for high voltage is presented. We have verified the effectiveness of high blocking voltage in the new device by using two dimensional devices simulator. We have analyzed the forward blocking characteristics , the latch up performance and turn off characteristics of the proposed structure. Specially, we have focused forward blocking of LIGBT. The forward blocking voltage of conventional LIGBT and the proposed LIGBT are 120V and 165V, respectively. . The forward blocking characteristics of the proposed LIGBT is better than that of the conventional LIGBT. This forward blocking comparison exhibits a 1.5 times improvement in the proposed LIGBT.

• Proceedings of the IEEK Conference
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• 2002.07a
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• pp.619-622
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• 2002

In this paper, we propose a new blocking method, multiple blocking, and examine the efficiency of the method in basic matrix operations. In the best case for the matrix multiplication C=AB＋C, the multiple blocking improves the performance by more than 10%, compared to the conventional single blocking method.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2020.11a
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• pp.202-204
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• 2020

We explored the blocking framework for regulating harmful content flooding the Internet. The procedure for obtaining content using the Internet was analyzed, and the technology for blocking content that can be applied at each stage of the acquisition process was investigated. Also, the characteristics and limitations of each blocking method were analyzed.

• Journal of Korean Ophthalmic Optics Society
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• v.19 no.2
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• pp.135-143
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• 2014

Purpose: To evaluate the blue-light blocking ratio and luminous transmittance of blue-light blocking lenses using the blue-light hazard function as specified in international standard. Methods: In order to calculate the blue-light blocking ratio and luminous transmittance for a total of 41 blue-light blocking lenses from 8 manufacturers, UV-Vis spectrophotometer was used for measuring the spectral transmittance of wavelengths from 380 to 780 nm. Blue-light blocking ratio was calculated using blue-light hazard function as specified in ANSI Z80.3:2010 and ISO 13666(or Korean Standard KS B ISO 13666:2004). Results: The range of the blue-light blocking ratio was from 9.3 to 96.8%, the range of the transmittance from 53.5 to 92.7%, and the range of the luminous transmittance from 58.0% to 98.1%. In general the blue-light blocking lens prepared by coating tended to have a higher luminous transmittance, while those prepared by tinting a higher blue-light blocking ratio. Conclusions: The behavior of the spectral distribution of lenses showed the possibility of the performance improvement in the blue-light blocking lenses. Manufactures need to acquire their own technology that can evaluate the performance of blue-light blocking lens based in international standard.

• Korean Journal of Applied Biomechanics
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• v.17 no.4
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• pp.57-64
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• 2007

The purpose of this study was to investigate comparative analysis of the vertical ground reaction force variables during landing from vertical jump blocking in volleyball through GRF analysis system. The subjects participated in this study were 6 male university volleyball player and 6 male acted as a control group. The results are as follows: 1. The skilled group was longer than the unskilled group in flight time during vertical jump blocking. 2. The skilled group was faster than the unskilled group in tFz2 during landing from vertical jump blocking. 3. The skilled group was higher than the unskilled group in Fz2 during landing from vertical jump blocking. 4. The skilled group was higher than the unskilled group in Fz2LR during landing from vertical jump blocking. 5. The skilled group was higher than the unskilled group in impulse during landing from vertical jump blocking. Consequently, during landing from vertical jump, the landing strategy of the skilled group was found as a form of a stiff landing. Therefore, this landing strategy will be required to strengthen of hip and knee extensors and ankle plantar flexors for injury prevention.

• The Journal of the Korea Contents Association
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• v.4 no.2
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• pp.1-6
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• 2004

This paper proposes on the acoustic signal processing blocking method of Internet pornographicl sites by calculating correlation values between prototype acoustic signals and input acoustic signals. Pre-existing blocking methods mainly focused on directory-based bled(fin and pornographic related words-based blocking. But these methods are not completely blocked the Internet harmful pornographicl sites by several situations. For this, this paper proposes the content-based blocking method which composes of the image-based blocking and the acoustic-based blocking. This paper, mainly, deals with the acoustic -based blocking method. Finally, the effectiveness of this system is demonstrated by several experiments.