• Journal of the Korea Academia-Industrial cooperation Society
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• v.13 no.3
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• pp.1310-1318
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• 2012

This study presents a new system that can make up for the decrease in identification rate due to the environmental or physical factors of a fingerprint identification system, which is most actively used among existing biometric systems. Considered most usable in life among many types of biometrics due to the convenience of use, smaller initial investment, and the smaller size, fingerprint identification is widely used in diverse applications. However, a fingerprint identification system has several defects, including environmental factors, physical skin damage, and variable sensor contact, lowering the identification rate in comparison to other biometric systems. On the basis of the existing fingerprint system, this study presents a more efficient system that can improve the identification rate by getting additional biometric information and three-dimensional finger type information through the use of simple and inexpensive additional equipment, which can be used in diverse areas.

• The Journal of the Acoustical Society of Korea
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• v.34 no.3
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• pp.210-218
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• 2015

When the driving voltage of an ultrasound transducer is increased to improve the quality of ultrasound images, heat is generated inside the transducer that can cause patient's skin burn and degradation of transducer performance. Hence, in this paper, a method to disperse the heat of the transducer has been studied. The phased array transducer having 3 MHz center frequency and 32 channels was selected for analyses of the thermal dispersion. First, mechanism of the heat generation was investigated in relation to the transducer operation through theoretical analysis, and material damping and sound pressure amplitude were confirmed to be influential on the heat generation. Further, we investigated the effects of the properties of the materials constituting the transducer on the thermal dispersion through finite element analysis. Based on the analysis results, we determined the thermal properties of the constituent materials that could facilitate the thermal dispersion inside the transducer. The determined thermal properties were applied to the finite element model, and the results showed that the maximum temperature at an acoustic lens contacting with a patient was decreased to 51 % of its initial value.

• Tunnel and Underground Space
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• v.13 no.6
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• pp.444-454
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• 2003

Rock fragmentation technique by cutter penetration has widely been used in the mechanical tunnel excavation. Microcracks propagate and interact because of locally concentrated high stress induced by cutter penetration. which is caused by heterogeneity of rocks. In this study Weibull distribution function and degradation index are used to consider the strength heterogeneity of a rock and the degradation of rock properties after failure. Through the numerical analyses, it is shown that the lateral pressure has an important influence on the rock fragmentation. In the single cutter penetration, large chips are formed as lateral pressure increase. The cutter spacing is also an important factor that affects the rock fragmentation in the double cutter penetration. The fragmentation efficiency of the double cutter penetration is better when cutter spacing is 70 mm than 40 mm and 100 mm. From the results, it is expected that this study can be applied to a TBM tunnel design by understanding of chipping process and mechanism of rock due to cutter penetration.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.31 no.3
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• pp.125-130
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• 2008

Multivariate analysis is a rapidly expanding approach to data analysis. One specific technique in multivariate analysis is Principal Component Analysis (PCA). PCA is a statistical technique that linearly transform a given set of variables into a new set of composite variables. These new variables are orthogonal to each other and capture most of the information in the original variables. PCA is used to reduce the number of control points to be checked by measurement system. Therefore, the structure of the data set is simplified significantly It is also shown that eigenvectors obtained by conducting principal component analysis on the basis of the covariance matrix can be used to physically interpret the pattern of relative deformation for the points. This case study reveals the twisting deformation pattern of the underbody which is the largest mode of the total variation.

• Membrane Journal
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• v.23 no.3
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• pp.220-225
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• 2013

Hydrophilic monomers were polymerized for lamination on polyvinylidene fluoride (PVDF) membrane surface for hydrophilization of the membranes. Hydrophilization reduced the contact angle from $95^{\circ}$ to $55^{\circ}$ and enhanced the water flux by 10 times while it reduced the bovine serum albumin (BSA) adsorption amount to 1/4 level. Thermal polymerization process was optimized by examining several operation parameters. Dimethyl oxobuthyl acrylamide (DOAA) showed the best effect due to its better hydrophilicity than others. Increase of amount of monomer enhanced the performance until the optimum concentration of 30 wt%, beyond which excess amount of monomer resulted in homopolymerization to deteriorate the performance. Azobis (isobutyronitrile)(AIBN) initiator has greater activation temperature range than benzoyl peroxide (BPO) and it showed better hydrophilation performance. Two stage lamination process, application of initiator followed by monomer addition, was more effective than one stage process, addition of initiator and monomer at once, which still reduced the contact angle but also reduced the water flux by pore blocking phenomena.

• Korean Journal of Environment and Ecology
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• v.18 no.3
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• pp.297-305
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• 2004

The purposes of this study were to understand visitors' park use characteristics and provide effective directions fur managing facilities and programs of ecological interpretation in Incheon Grand Park, Korea. To accomplish the purposes of study, a questionnaire survey with 376 samples was carried on the park. As for the results, most respondents were pointed relaxation with natural environment as a main visiting purpose. Visitors highly interested in programs of ecological interpretation and also respondents' intension of participation to those programs showed far more positive. Based on the results, there was a need fer introducing facilities and programs of ecological interpretation as a park management strategy in order to induce nature-friendly park use and connect to environment education in the school system. In addition, some suggestions which should be developed a base facilities and various programs were made.

• Journal of the Korean Geographical Society
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• v.39
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• pp.93-114
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• 1989

거의 해마다 내습하는 태풍위험을 제주지역 농부들이 어떻게 인식하고 그에 적응하고 있는지 아울러 이와같이 연례행사처럼 발생하는 태풍재해 문제 해결에 있어 정부관계기관의 역할에 대한 그들의 인식은 어떠한가를 살펴보는 것이 본 연구의 목적이다. 우선 위 연구과제를 살피기 위하여 다음과 같은 세 가지 가설이 전제되었다. 첫째, 태풍과 같은 자연발생적 위협과 빈번한 접촉내지 오랜 경험은 인간에게 위험과 손실을 준다는 자각으로 이끌며 또한 장차 발생의 정확한 예측에 비교적 밀접한 관계를 갖는다. 그리고 이러한 경험들은 그와같은 자연발생적 위협으로부터 일시 피하거나 위협지역으로부터 아주 떠나 버린다기 보다 오히려 적응이라는 선택을 취한다. 둘째, 인간이 이와같은 위협지역 제주도와 같이 사회문화적인 특성이 뚜렷한 지역에 삶의 터전을 가지고 있는 것은 경제적 요인에서라기보다도 사회문화적 바탕에서 그 원인을 찾을 수 있다. 셋째로, 정부의 이와같은 자연발생적 재해문제 해결은 해당 지역 거주주민들과 보다 긴밀한 컴뮤니케이션과 함께 정부나 컴뮤니티를 통한 자연재해에 관한 계몽교육을 강화함으로서 그 역할이 효과적으로 수행될 수 있다. 총 113명의 농업을 주업으로 하는 가구주들을 제주도의 상습태풍재해지구에서 무작위 단게별군집(Random-cluster Stratified Sampling)방법에 의하여 선별하고 태풍위협에 대한 개인별 재해인식과 인간 적응을 알아보기 위하여 작성된 설문서를 통하여 각기 면담, 연구분석자료가 수집되었다. 제주농부들의 태풍에 대한 자각과 적응은 제주도 나름의 풍토에서 오랜 삶의 경험을 토대로 얻어진 결과라는 것이 입증되었다. 한편, 장차 태풍 내습에 대한 그들의 예측은 상당히 정확하였으며, 태풍재해에 대한 적응은 동기적이고 예방적 즉, 농부들은 재해의 근원적 소멸을 위해 재해지역을 떠난다기보다 오히려 피해를 감수하고 있었으며 또한 그들의 기본 영농방법이나 작물의 대체를 급격히 전환한다기 보다 부분적으로 수정, 변경시켜 나가고 있는 것으로 나타났다. 한편, 그들의 적응과정은 현대적 영농기술과 그들 특유의 전통적 방법을 혼합 병행하고 있었으며 가족이나 친척 이웃과의 유대관계가 재해지역에 거주하는 지배적 이유로 나타났다. 또 한편, 해당연구지역 농부들은 태풍피해에 대한 정부의 보조를 알고는 있으나 그것이 재해문제를 해결하는데 있어서 효율적이라고 생각치 않고 있다. 그들은 더욱 많은 재정적 보조를 희망하는 것만큼 연례저긍로 내습, 피해를 주고 있는 태풍재해 문제에 대한 정부의 적극적이고 좀더 효과적 예방 대책을 요구하고 있다.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.41 no.12
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• pp.13-19
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• 2004

We have been studied on the high concentration ozonized water production technology which substitute for the SPM wet cleaning solution process as the PR strip process after the photolithography process in the semiconductor and flat panel display manufacturing. In this work, we have developed the surface discharge type ozone generator which has the characteristics of the 12 ［wt%］ ozone concentration at the oxygen gas flow of 0.5［ℓ/min］ oxygen per cell and also developed the high efficiency ozone contactor for the mixing ozone gas with deionized water. As the production test results of the ozonized water, we obtained the ozonized water concentration above 80［ppm］ at the 10［wt%］ ozone gas concentration, and also had a good result of the PR strip rate of 147［nm/min］. at the 70［ppm］ ozonized water.

• Applied Chemistry for Engineering
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• v.26 no.6
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• pp.686-691
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• 2015

A basic research for utilizing solid refuse fuel (SRF) based on changing SRF properties (RDF, RPF) and types (pellet, fluff) is demonstrated. Physicochemical characteristics of SRF and also changes in thermal decomposition depending on combustion time and emission gas (NOx, CO, HCl, etc) concentration were investigated for applications to waste energy sources. In conclusion, RPF is easy to pelletize, and has better combustion efficiency, higher LHV, higher thermal reduction, and short combustion time because it is composed of plastic wastes homogeneously. Also, fluff type samples have better combustion efficiency, and short combustion time because it has wider exposed surface area for combustion. It can also save energy consumption for pelletizing.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.45 no.5
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• pp.12-20
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• 2008

RFID(Radio frequency indentification) technology, that the reader detect the tag information attached on the objects without contact, is considered the kernel of realizing tile Ubiquitous Sensor Network. Particularly, because there are lots of tags(which the reader have to detect) in the UHF RFID system(that is applied at the Logistic & Distribution industry). In the UHF RFID system the negative effects, we called the tag-collision, may occur and we should solve these effects. So, in the EPCglobal Gen2 protocol they present the Slotted Random Anti-collision algorithm to prevent the tag-collision effect. In this paper, in order to minimize the tag-collision effect and bring on the system efficiency, we propose the Power Increasing Method that controls the transmission power of the reader depending on the environment and verily the improved performance.