• 펄프종이기술
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• 제32권3호
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• pp.25-31
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• 2000

It is required to use substantial amount of wet strength resin for producing multi-functional mulch papers since these paper products shold maintain its strength properties when they exposed to outdoor weather for several months. While producing mulch papers it is usual to observe significant amount of foam at white water silo. Thus it is imperative to use defoaming or antifoaming agents. In this study diverse defoaming and antifoaming agents have been tested for their effective-ness in eliminating foams that produced. It was shown that combined use of a silicone type defoamer and a fatty acid type anti-foaming agent was msot effective in eliminating foams. These chemicals were used in trial production of mulch papers and their influence on paper-making wet end system was examined including one pass retention cationic demand con-ductivity pH etc. It was found that the defoaming agents were very effective for removing foams in trial production. Tensile strengths of the mulch papers produced were significantly greater than commericial mulch papers produced in Japan.

• 한국의류학회지
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• 제28권1호
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• pp.112-118
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• 2004

Recently, as the percentage of women employment has been growing, the demand for various facilities and services regarding household duties and infant rearing is increasing and so do the amount of the disposable diaper used. Among the components of disposable diaper, the top sheet contacting with infant skin directly is usually made with nonwoven textiles. Therefore, the mechanical and surface characteristics of the nonwovens used in disposable diaper are important for the skin health of infants. In this study, we have explored the mechanical and surface properties, such as friction coefficient, fluid permeability and strength, of the nonwovens used for disposable diaper top sheet and observed the variation of their properties with abrasion cycles. Nonwoven materials examined in this study are 100% cotton spunlace, 100% tencel spunlace, 100% polypropylene (PP) thermal bonding and 100% PP air through (Thru-air bonded carded web). From the result of KES-F analysis, we've found that 100% PP air through type nonwoven had a low friction coefficient and showed a little change in surface properties as increasing abrasion cycles. Moreover, it revealed superior fluid permeability and quick-drying character. On the other hand, though showing an excellent absorption force, the spun lace type nonwoven made of 100% cotton and 100% tencel displayed relatively low abrasion strength especially in wetting condition.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2005년도 추계 학술논문 발표대회
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• pp.29-32
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• 2005

Recently, for the problem solution of demand and supply imbalance of fine aggregate due to the shortage of natural fine aggregate and the environment regulation on sea sand extraction in the construction field, the studies for the application of recycled fine aggregate using waste concrete are being progressed versatilely. The purpose of this study is to investigate quality of recycled fine aggregate manufactured by drying manufacturing system which is the manufacture method of high duality recycled fine aggregate, and to analyze on thehardened and durability properties of recycled concrete using it. Therefore it is to present the fundamental data for application and utilization of recycled concrete. The results of this study are as follows; Quality of recycled fine aggregate by drying manufacturing system is improved, and compressive strength, carbonation depth and chloride ion penetration depth of recycled concrete using high quality recycled fine aggregate are similar to those of normal concrete using natural and crashed sand. But, resistance to $H_{2}SO_{4}$ show decreased somewhat.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2018년도 춘계 학술논문 발표대회
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• pp.228-229
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• 2018

In the construction industry, we have set goals such as reduction of greenhouse gas emissions and reduction of energy use. In particular, reduction of CO₂ emissions in the concrete manufacturing process, reduction of industrial waste and industrial wastes into concrete The zero-emission level of reuse as a resource is under review. On the other hand, the cost of stone is expensive due to small quantity production of domestic stone production in order, it is difficult to carry and construct with heavy material, and it takes long time to construct. In order to solve the shortage of supply and demand of natural stone, various kinds of stone powder, artificial stone made by putting stone texture on the surface of mortar or concrete, fiber reinforced plate, tiles and the like are increasingly used. In this study, the artificial stone using slag and recycled aggregate instead of natural stone was fabricated and the strength characteristics were evaluated for its applicability and feasibility.

• Earthquakes and Structures
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• 제8권6호
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• pp.1277-1297
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• 2015

Post-tensioned precast segmental bridge columns have shown high level of strength and ductility, and low residual displacement, which makes them suffer minor damage after earthquake loading; however, there is still lack of confidence on their lateral response against severe seismic loading due in part to their low energy dissipation capacity. This study investigates the influence of major design factors such as post-tensioning force level, strands position, columns aspect ratio, steel jacket and mild steel ratio on seismic performance of self-centring segmental bridge columns in terms of lateral strength, residual displacement and lateral peak displacement. Seismic analyses show that increasing the continuous mild steel ratio improves the lateral peak displacement of the self-centring columns at different levels of post-tensioning (PT) forces. Such an increase in steel ratio reduces the residual drift in segmental columns with higher aspect ratio more considerably. Suggestions are proposed for the design of self-centring segmental columns with various aspect ratios at different target drifts.

• Earthquakes and Structures
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• 제8권6호
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• pp.1435-1452
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• 2015

The performance of masonry infilled frames during the past earthquakes shows that the infill panels play a major role as earthquake-resistant elements. Experimental observations regarding the influence of infill panels on increasing stiffness and strength of reinforced concrete structures reveal that such panels can be used in order to strengthen reinforced concrete frames. The present study examines the influence of infill panels on seismic behavior of RC frame structures. For this purpose, several low- and mid-rise RC frames (two-, four-, seven-, and ten story) were numerically investigated. Reinforced masonry infill panels were then placed within the frames and the models were subjected to several nonlinear incremental static and dynamic analyses. In order to determine the acceptance criteria and modeling parameters for frames as well as reinforced masonry panels, the Iranian Guideline for Seismic Rehabilitation of Existing Masonry Buildings (Issue No. 376), the Iranian Guideline for Seismic Rehabilitation of Existing Structures (Issue No. 360) and FEMA Guidelines (FEMA 273 and 356) were used. The results of analyses showed that the use of reinforced masonry infill panels in RC frame structures can have beneficial effects on structural performance. It was confirmed that the use of masonry infill panels results in an increment in strength and stiffness of the framed buildings, followed by a reduction in displacement demand for the structural systems.

• Earthquakes and Structures
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• 제8권6호
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• pp.1349-1362
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• 2015

This paper presents an analytical study aimed at evaluating the effectiveness of using buckling-restrained braces (BRBs) in mitigating the seismic response of a case study 6 storey reinforced concrete (RC) building. In the design of the BRBs with non-prismatic cross-sections, twelve combinations of ${\alpha}$ and ${\beta}$ design parameters that influence the strength and stiffness of the BRBs, respectively, were considered. The response of the structure with and without BRBs under earthquake ground accelerations were evaluated through nonlinear dynamic analysis. Two sets of ground motions representative of the design earthquake with 10% and 50% exceedance probability in fifty years were taken into account. By comparing the structural performance of the original and buckling restrained braced structures, it was observed that the use of the BRBs were very effective in mitigating the seismic response as a retrofit scheme. However, the selection of the strength and stiffness parameters of the BRBs had considerable effect on the response characteristics of RC structures. For instance, by increasing the value of ${\alpha}$ and by decreasing the value of ${\beta}$ of the buckling-restrained braces, the maximum deformation demand of the structures increased.

• Corrosion Science and Technology
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• 제9권5호
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• pp.175-186
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• 2010

The auto industry is demanding more ductile high-strength steel grades to build lighter and stronger car bodies. The hot-dip galvanizing problems of these new steel grades are creating a demand for an improved method to control zinc wettability. The simplest way to improve zinc wettability on industrial hot-dip galvanizing lines is to increase the strip immersion temperature at zinc bath entry for enhancing the aluminothermic reaction. However, this practice increases the reactivity due to overheating the zinc in the snout which induces the formation of brittle Fe-Zn compounds at the strip/coating interface with the formation of higher amounts of dross in the zinc bath and snout contamination. Thus, this simple practice can only be utilized for short production periods of one to two hours without deteriorating coating quality. This problem has been solved by employing a technique that allows the use of a higher and attuned strip immersion temperature at zinc bath entry while still maintaining a constantly low zinc bath temperature. This has been proven to provide the solution for both the improved wettability and a significant reduction in the amounts of dross in the zinc bath.

• 대한소아치과학회지
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• 제23권4호
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• pp.800-817
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• 1996

In this study, we tried to evaluate the effect of Amalgambond liner application on the degree of marginal leakage and retention of amalgam restoration by comparing with that of the Copalite and All-bond 2. The results obtained from this experiment were as follows; 1. Tensile strength representing the bond between amalgam and tooth structure was the highest in Amalgambond, and All-Bond 2, Copalite in descending order. There were statistically significant difference between each group(P<0.05). 2. The degree of microleakage in Amalgambond was lower than that of All-Bond 2, and Copalite, but no stastically significant difference could be found (P>0.05). 3. The liner such as Amalgambond or All-Bond 2 were evaluated to be superior to the conventional Copalite in bond strength as well as in microleakage. But the result of this study could not show the superiority of one material over the others; Amalgambond and All-bond 2. Besides the results of the study, other factors, such as practical convenience, should be considered in determining the selection of material. The support of welldesigned clinical studies on this subject are in demand.

• 한국측량학회지
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• 제18권2호
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• pp.191-198
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• 2000

수치사진 측량은 신속한 정보 획득과 갱신을 통하여 지리정보체계의 데이터 베이스 구축에 중요한 역할을 하고 있다. 이러한 수치사진측량의 기본적인 처리과정 중의 하나는 영상정합이다. 그러나 어떠한 영상정합 알고리즘도 인간의 판단과 지적 능력에 의해서 수행되는 것만큼 만족스러운 결과를 산출하지는 못하고 있다. 따라서 본 논문에서는 대상지역이 완만한 경우 정합점이라고 판단되는 점과 그 이웃 점들간에 전체적인 유사성을 관측하여 불량 정합점들을 제거하는 방법(정합 강도의 측정)을 제안하였고, 또한 최종적으로 얻어지는 정합점들의 3차원 좌표를 광속 조정법을 통하여 구하였다 실험결과 제안방법은 불량정합점들을 효과적으로 제거하였고, 계산된 3차원 지상좌표도 허용 오차 범위 이내로 들어왔다.