• Journal of Welding and Joining
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• v.17 no.2
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• pp.97-103
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• 1999

The dynamic resistance monitoring in primary circuit is one of the important issues. Because in-process and real time quality assurance of resistance spot weld is needed to increase the product reliability. In this study, new dynamic resistance detecting method is proposed as a practical manner of weld quality assurance using instantaneous current and voltage measured at the primary circuit. and also, various patterns of primary dynamic resistance curve are characterized with the macro photograph and the weldability lobe curve. It is found that the primary dynamic resistance patterns are basically similar to those of the secondary, but there is evident advantage such as no extra devices are needed to obtain the quality information and eventually real time feedback control will be possible.

• Proceedings of the Korean Information Science Society Conference
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• 2001.10a
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• pp.265-267
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• 2001

일반적으로 효율적인 질의.검색.분석을 수행하기 위해서 이질적이고 분산된 정보 소스들 부터 통합된 정보를 포함한 데이터 저장고를 데이터 웨어하우스라 일컬으며, 이를 웹기술과 접목한 기술을 웹 웨어하우징이라 한다. 본 연구에서는 웹 웨어하우징 기술의 모토가 될 수 있는 기술로서 분산되어 저장된 다양한 소스 데이터에 대해 실체 뷰로 간과되어지는 데이터 웨어하우스에 관한 유지 방법에 관한 연구이다. 본 연구의 성능 평가를 위해서 기존에 알려진 보상알고리즘, 모든 기본 릴레이션에서 키 애트리뷰트들을 포함해야만 하는 스트로브와 이를 완화시켜서 성능향상을 보이는 스윕 알고리즘들을 각각 특성별로 비교하며, 전송된 바이트 수와 갱신된 회수에 따른 성능 평가 및 갱신 유형에 따른 성능 평가를 수행하여 결과를 보인다.

• Journal of the Korean Society of Mechanical Technology
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• v.13 no.4
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• pp.143-148
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• 2011

This study analyzes the resistance spot weldability of DP60 steels. To analyze the resistance spot weldability of DP60 steels, tensile strength test and macro-section test were conducted for the resistance spot welds. Acceptable welding conditions were determined as a function of the resistance spot welding process parameters such as electrode force, welding time, and welding current. The lower limit of the welding lobe was the minimum shear tension strength for 590MPa-grade steel while the upper limit was determined whether or not expulsion was detected.

• Journal of the Korean Institute of Landscape Architecture
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• v.16 no.2
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• pp.1-7
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• 1988

Predicting treeform should be very important, eventhough it is difficult, step for landscape designers. This study was carried out to develop a method to classify the treeforms of landscape plants by numerical data. Twenty five treeforms are selected to be compared with 41 Zelkova serrata MAKINO, 26 Pinus strobus L., and 44 Magnolia denudata DESROUX. Statistical judgement was made by using X$^2$-Test. The results are summerized as follows. 1. Zelkova serrata was classified as B3 or C3. This species showed a tendency of changing from A type to B or C type, and the CL/CH ratio(canopy length/canopy height) is thought to be increased as aged. 2. pinus strobus was classified as D4-D5 and the CL/CH ratio tends to be increased as aged. 3. Magnolia denudata was classified as D4 and the change by aging was not observed clearly.

• Journal of Korean Society of Forest Science
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• v.62 no.1
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• pp.76-81
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• 1983

Pedicularis spp. are the alternate hosts of the white pine blister rust fungi in the forests of Korea, and Ribes spp. were found as other alternate hosts by artificial inoculation test. New biotypes (races) with different host selectivity and pathogenicity of the causal fungi were speculated at various places in Korea. The aeciospores of the fungi were collected from two isolated places, Pyeongchang and Namwoen, and artificially inoculated on Pedicularis resupinata and six species of the genus Ribes. Among the tested alternate host species, P. resupinata and R. montigenum were only susceptible to both the Pyeongchang population and the Namwoen population, showing similar pathogencity between the two fungai populations. Three white pine species were planted in fungus-infested stands to study the susceptibility of each tree species. Four years later, 17.7% of Pinus koraiensis and 26.3% of the P. strobus were infected, but P. parviflora was free from attack. From the above results, it was concluded that the white pine blister rust fungus populations in Korea are of the same biotype, with P. koraiensis and P. strobus as aecial hosts, and Pedicularis spp. and Ribes spp. as telial hosts.

• Journal of the Korean Wood Science and Technology
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• v.43 no.4
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• pp.478-485
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• 2015

The aim of this study is to analyze the combustion and thermal properties in order to establish baseline data for the fire safety evaluation of domestic timbers. The combustion properties such as heat release rate, total heat release, gas yield, and mass loss were analyzed by the method of cone calorimeter test and thermogravimetry (TGA). Thermal decomposition temperatures of the specimens by TGA were recorded as $359.83^{\circ}C$ for White pine, $359.80^{\circ}C$ for Red-Leaved Hornbeam, $363.14^{\circ}C$ for Carolina poplar, $358.59^{\circ}C$ for Konara oak, and $362.11^{\circ}C$ Sargent cherry. Red-Leaved Hornbeam showed the highest value of heat release rate, but, Carolina poplar wood showed the lowest value. In case of the total heat release, Red-Leaved Hornbeam wood showed the highest value and Carolina poplar wood showed the lowest one. The gas analysis results showed that Sargent cherry wood had the lowest value of 0.021, and Konara oak had the highest at 0.031 in the $CO/CO_2$. The minimum value of mass reduction was recorded as 87.57% for Sargent cherry, but, on the other hand, it was 95.03% for Konara oak. There was a correlation between the gas generation of CO and $CO_2$, and combustion behavior of woods. These results are expected to be usful for providing a fundamental guideline with the fire safety of wood use in interior applications.

• Journal of Korean Society of Forest Science
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• v.104 no.1
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• pp.35-42
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• 2015

The purpose of this study is to offer the raw data for improving the method of landscape planting in apartment complex by objective surveying and analysing the growth ratio by type and ground planted in landscape tree. The results are as follows. In the survival ratio of tree, Pinus densiflora was the highest and Abies koreana was the lowest in evergreen tree. In case of deciduous tree, the species of the highest survival ratio were Diospyros kaki, Zelkova serrata, Prunus mume, Lagerstroemia indica and Ginkgo biloba. There showed that Sorbus commixta and Chaenomeles sinensis had the lowest survial ratio. In case of tree growth by types, Pinus strobus was the highest and Pinus densiflora var. globosa was the lowest among evergreen trees. Among deciduous trees, the growth ratio of Zelkova serrata was the highest, and the trees showed the lowest growth were Lagerstroemia indica, Magnolia denudata and Cornus officinalis. Pinus strobus, Cornus kousa, Ginkgo biloba, Chionanthus retusa and Acer palmatum were good growth in natural ground, and Zelkova serrata and Prunus armeniaca var. ansu were good in artificial ground. In the future, if you study the growth characteristics and shrubs that are excluded from the study of landscape trees in various locations are expected to derive objective data.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.22 no.3
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• pp.336-344
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• 2011

The purpose of this study is to analyze the radiation-pattern characteristics above 1 GHz for the electromagnetic wave radiated from multi-slot such as ventilations, etc. on the enclosure of an EUT and so to make recommendations for suitable test methods. An experimental EUT was formed by putting a comb-generator at the center of a rectangular enclosure with 4 slots, and its radiation pattern was analyzed in the frequency range of 1~6 GHz. As analysis results, multi-lobe appears above 2 GHz and the number of multi-lobes is growing as the frequency increases. And real radiated-emission measurements were performed for the experimental EUT by scanning a receiving antenna in the height of 1~4 m and tilting toward maximum radiation, as well as setting the height of a receiving antenna to the central position of the EUT which is prescribed at the present standards. The measured results are +12.8 dB in the scanning and +16.4 in the scanning and tilting compared with the present standard test method. Therefore, the latter must be revised in order to consider the radiation pattern above 1 GHz.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.29 no.11
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• pp.828-833
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• 2018

It is well known that reflected waves and resonance affect phase distortion. In addition, phase delay can be distorted by antenna impedance. In this study, we analyze the phase delay variation caused by the antenna impedance, considering mutual coupling effects. In addition, we confirm the beam steering characteristics. When was -10 dB and -7 dB, the maximum phase delay error was $18.5^{\circ}$ and $26.5^{\circ}$, respectively. The Monte Carlo simulation with an eight-element linear array antenna demonstrated that the RMS error of the beam steering angle ranged from $0.19^{\circ}$ to $0.4^{\circ}$, and the standard deviation ranged from $0.14^{\circ}$ to $0.33^{\circ}$ when the beam steering angle was in the range of $0^{\circ}$ to $30^{\circ}$, with the uniformly distributed phase error of $18.5^{\circ}$ and $26.5^{\circ}$. The side lobe level increased from 0.74 dB to 1.21 dB by the phase error from the theoretical value of -12.8 dB, with a standard deviation of 0.31 dB to 0.51 dB. This is verified by designing an eight-element spiral array antenna.

• Journal of Welding and Joining
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• v.30 no.6
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• pp.68-73
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• 2012

Nowadays, car manufacturers tried to improve automotive fuel efficiency, and applied many high strength steels such as AHSS or UHSS to car bodies. Therefore, the number of steel combinations for the resistance spot welding are dramatically increased and the need for weldability evaluation of these combinations are also required. In this study, we suggest the lobe curve using FEM simulations for DP780 steel with 1.0t, 1.4t. The lobe curves which could expressed weldablity and optimal welding condition were obtained according to 6 steel combinations. There were two combinations for same steel sheet which were DP780 1.0t, DP780 1.4t. Dissimilar steel sheet combination with different thickness was 1.0t and 1.4t of DP780. Different steel combinations were DP780 1.0t and SPRC440 1.0t, and DP780 1.0t and DP590 1.0t. Finally dissimilar combinations was and DP780 1.0t and DP590 1.4t. The trend of low boundary and high boundary variation of lobe curve were analyzed with a viewpoint of the contact resistance and the heat input.