• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2003년도 가을 학술발표회 논문집
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• pp.252-255
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• 2003

Recently, there is a growing trend in the United States toward replacing latex additives in polymer-modified cement mortars with redispersible polymer powders. This movement is relatively new in the U.S. but is further advanced in Europe due to the more extensive use of cement and concrete in residential construction. Hitherto, in Korea - there is a very diminutive movement towards this growing trend. Thus, there is limited availability of data on redispersible polymer powders. This study investigates the effectiveness of redispersible polymer powder on improvement of the mechanical properties of modified mortar. It was concluded from the results of the experiments that the size of the dispersed polymer particles, variations in glass transition points (Tg), and variations in minimum film formation temperature (MFT) influenced the strength development of the modified mortars, and optimum strength in modified mortars using redispersible powders can be achieved when the Tg which accounts for the degree of powder flexibility is considered.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2011년도 추계 학술논문 발표대회
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• pp.107-108
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• 2011

The purpose of present study is to examine the application of effective curing to hardener-free epoxy-modified mortars. The epoxy-modified mortars are prepared with polymer-cement ratios, subjected to two types of curing conditions, and tested for compressive, flexural and tensile strengths. As a result, hardener-free epoxy-modified mortars with steam curing is markedly improved with increasing air-dry curing period. High strength development of the epoxy-modified mortars may be achieved by the dense microstructure by cement and the hardener of the epoxy resin in the mortars.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2001년도 합동 추계학술대회 논문집 정보 및 제어부문
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• pp.187-190
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• 2001

A new ultrasound imaging technique based on simultaneous multiple transmit focusing using orthogonal modified Golay codes is presented. modified Golay codes are used to increase signal-to-noise-ratio(SNR) and maximize the transmit power efficiency(TPE). Conventional Golay codes consist of a pair of complementary codes with same length and can be compressed into a delta-like signal due to their complementary property. In the present work, two modified Golay codes focused at different depths are transmitted at the same time, which are mutually orthogonal. On receive, these orthogonal modified Golay codes are separately compressed into two short pulses and individually focused. These two focused beam are combined to form a frame of image with improved lateral resolution. Computer simulations are performed to verity the proposed method improves the lateral resolution of image compared with the conventional echo system.

• 한국세라믹학회지
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• 제27권7호
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• pp.833-840
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• 1990

For the development of multi-functional materials which has water reducing power, air entraining power and waterproofing power as well as blending additive in cement mortar the coal ash was modified with asphalt-stearic acid or asphalt-boiled oil mixtures by mechanical treatment. And the physical properties of cement mortar blended with modified coal ashes were compared with those of the water-tightness-cement mortar and the ordinary-portland-cement mortar added with AE.water reducing agent. The mortar of coalash-blend-cement modified with asphalt-stearic mixture was increased acid about 20% in initial strengths and decreased about 20% in water absorption ratio than those of ordinary coalash-blend-cement. The mortar of coalash-blend-cement modified with asphalt-bolied oil mixture was similar to the cement mortar added with AE.water reducing agent in water reduction ratio, air entraining conents and the initial strengths, also was similar to the water-tightness-cement mortar in water absorption and water permeability ratios.

• 대한전자공학회논문지SD
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• 제48권4호
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• pp.1-5
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• 2011

변형된 modified double weight code를 사용하여 효율적인 spectral-amplitude-coding optical CDMA를 구현하였다. 수신단의 optical decoder 앞에 fiber Bragg grating(FBG)을 사용하여 이 시스템의 주된 잡음인 phase-induced intensity noise(PIIN)를 대폭 줄여 향상된 시스템의 특성을 보일 수 있었다.

• 대한전자공학회논문지SD
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• 제48권8호
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• pp.5-9
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• 2011

Hadamard code를 이용한 spectral-amplitude-coding optical code-division multiple-access(OCDMA) 시스템은 $2^n$개의 code length만을 갖는 특성을 지니어 최대 사용자 수의 조절이 어렵고 phase-induced intensity noise(PIIN)가 커서 효율적인 시스템 구성이 어렵다. 이의 한계성을 극복할 수 있는 modified Hadamard codes를 제안하고 잡음 분석을 통하여 향상된 시스템 특성을 보인다.

• 한국환경과학회지
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• 제22권10호
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• pp.1287-1294
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• 2013

In this study, thermoplastic starch (TPS), cross-linked starch (CS), and cross-linked starch modified with glycerol (CTPS) were prepared, and the mechanical properties of the compatibilized low-density polyethylene (LDPE) blends (LDPE/TPS, LDPE/CS, and LDPE/CTPS) were investigated and compared with those of uncompatibilized LDPE/TPS, LDPE/CS, and LDPE/CTPS blends. Maleic-anhydride-grafted polyethylene was used as the compatibilizer. The enhanced tensile strength and elongation at break for the compatibilized LDPE/modified starch blends are a result of the improved compatibility between LDPE and the modified starch, which was confirmed by torque measurements and scanning electron microscopy.

• 한국공간구조학회논문집
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• 제16권4호
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• pp.117-123
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• 2016

The blast load is classified into free-air blast and surface blast following the location of explosion and surface. In this paper, several equations for blast load calculation are explained briefly and a modified equation for free-air blast load is suggested. The modified equation is based on Kingery-Bulmash equation which is used in UFC 3-340-02 and Conwep model. In this modified equation, the process of calculation is simplified against the original equation, and the number of coefficients is reduced under 5. As a result, each parameter of estimated data by modified equation has less than 1% of error range comparing with Kingery-Bulmash equation.

• 전자공학회논문지C
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• 제34C권5호
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• pp.33-42
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• 1997

In this paper, the modified inverse chebyshev low-pass function is analyzed in the frequency domain, time domain, and sensitivity characteristics as compared with the classical inverse chebyshev function. Unlike the classical function, the modified function exhibits progressively diminishing ripples in the stopband. So, the modified function has a great attenuation throughout the stopband except at the vicinity of a stop frequency and can be realizable in the passive doubly-terminated ladder network for the even order. The poles of the modified function move towards real axis by the effect of diminishing ripples. Thus the pole-Q, which is one of the valuable measurements to estimage the function characteristics, is reduced without increasing order. In the frequency and can be realizable in the passive doubly-terminated ladder network to examine the magnitude and pole-Q sensitivities.

• 한국주조공학회지
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• 제17권2호
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• pp.135-144
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• 1997

The relative machinability of the invar-type cast alloys, such as invar cast steel, invar-type cast iron, Meehanite cast iron, and the modified Invar-type cast iron containing Mo and V was evaluated based on the tool life test, the surface roughness test and the chipping test. Tool life and surface roughness were measured under various cutting conditions. The tool lives of Invar cast steel, Meehanite cast iron, the modified Invar cast iron and Invar cast iron was 12 min, 8 min, 1 min, 41 min, respectively. The surface finish of Invar cast steel and the modified Invar cast iron was better than that of Meehanite cast non, and the chip breakability of invar cast iron and Meehanite cast iron was better than that of invar cast steel. The Taylor's equations of invar cast steel and the modified invar cast iron were $VT^{0.3076}=154.479$ and $VT^{0.3880}=102.326$, respectively. As the cutting speed increases, the surface finish of the modified invar cast iron was improved.