• Journal of Magnetics
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• 제7권3호
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• pp.72-79
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• 2002

Local M-H loops have been measured on the free layer of a tunneling magnetoresistance (TMR) junction using the magneto-optical Kerr effect (MOKE) system, with an optical beam size of about 2 $\mu$m diameter. Tunnel junctions were deposited using the DC magnetron sputtering method in a chamber with a base pressure of 3$\times$10$^{-9}$ Torr. The relatively irregular variations of coercive force H$_c$(∼17.5 Oe) and unidirectional anisotropy field H$_{ua}$(∼7.5 Oe) in the as-deposited sample are revealed. After $200{^{\circ}C}$ annealing, He decreases to 15 Oe but H$_{ua}$ increases to 20 Oe with smooth local variations. Two-dimensional plots of H$_c$ and H$_{ua}$ show the symmetric saddle shapes with their axes aligned with the pinned layer, irrespective of the annealing field angle. This is thought to be caused by geometric effects during deposition, together with a minor annealing effect. In addition, the variation of root mean square (RMS) surface roughness reveals it to be symmetric with respect to the center of the pinned-layer axis, with the roughness of 2.5 $\AA$ near the edge and 5.8 $\AA$ at the junction center. Comparison of surface roughness with the variation of H$_{ua}$ suggests that the H$_{ua}$ variation of the free layer is well described by dipole interactions related to surface roughness. As a whole, the reversal magnetization is not uniform over the entire junction area and the macroscopic properties are governed by the average sum of local distributions.

• Journal of Magnetics
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• 제7권3호
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• pp.63-71
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• 2002

Three fabrication techniques for forming thin barrier layer with uniform thickness and large barrier height in magnetic tunnel junction (MTJ) are discussed. First, the effect of immiscible element addition to Cu layer, a high conducting layer generally placed under the MTJ, is investigated in order to reduce the surface roughness of the bottom ferromagnetic layer, on which the barrier is formed. The Ag addition to the Cu layer successfully realizes the smooth surface of the ferromagnetic layer because of the suppression of the grain growth of Cu. Second, a new plasma source, characterized as low electron energy of 1 eV and high density of $10^{12}$ $cm^{-3}$, is introduced to the Al oxidation process in MTJ fabrication in order to reduce damages to the barrier layer by the ion-bombardment. The magnetotransport properties of the MTJs are investigated as a function of the annealing temperature. As a peculiar feature, the monotonous decrease of resistance area product (RA) is observed with increasing the annealing temperature. The decrease of the RA is due to the decrease of the effective barrier width. Third, the influence of the mixed inert gas species for plasma oxidization process of metallic Al layer on the tunnel magnetoresistance (TMR) was investigated. By the use of Kr-O$_2$ plasma for Al oxidation process, a 58.8 % of MR ratio was obtained at room temperature after annealing the junction at $300{^{\circ}C}$, while the achieved TMR ratio of the MTJ fabricated with usual Ar-$0_2$ plasma remained 48.4%. A faster oxidization rate of the Al layer by using Kr-O$_2$ plasma is a possible cause to prevent the over oxidization of Al layer and to realize a large magnetoresistance.

• 화약ㆍ발파
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• 제30권2호
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• pp.21-28
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• 2012

사면 절취 및 도심지 터파기 등 인공적으로 사면을 형성하는 경우 경제적이고 효율적인 공법으로 화약을 이용한 발파공법이 많이 사용되고 있다. 절취면 보호를 위해 대상 암반에 손상을 주지 않고 암반이 가지고 있는 자연적인 강도를 그대로 유지할 수 있도록 발파하는 것이 중요하며 사회적으로 문제 시 되는 발파공해를 고려하여 발파진동을 저감할 수 있는 공법이 필요하다. 본 연구에서는 평활한 절취면 형성을 위하여 도폭선에 폭약을 등간격으로 배치하고 장약의 방법과 전색의 방법을 달리하여 발파를 진행하였다. 4가지 패턴을 사용하여 총 60공에서 20회 발파를 실시하였으며 발파원으로부터 15~120m 거리에서 발파진동소음측정기를 사용하여 진동속도를 측정하여 310개의 데이터를 획득하였다. 측정된 진동속도 데이터를 분석하여 발파진동을 저감하고 효율적이고 경제적으로 절취면을 보호할 수 있는 방법을 연구해 보았다.

• 한국철도학회논문집
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• 제16권5호
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• pp.379-385
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• 2013

본 연구에서는 IGM 구간에서 주면마찰력을 활용하여 지지력을 확보하기 위해 선단부에만 부분적으로 현장타설말뚝을 시험시공하고 IGM 이론의 적용성을 분석하였다. 시험시공 현장의 지반조사와, 교란여부, 거칠기 상태를 측정하여 IGM 이론 적용을 위한 지반특성을 점성, 비교란, 매끄러운 상태로 분석하였다. 또한, 정재하시험 및 하중전이시험을 통해 허용지지력과 심도별 주면마찰력을 산정한 결과, 주면마찰력은 심도가 깊어질수록, 기준침하량이 클수록 증가하는 것으로 평가되었으며, 심도와 매우 높은 상관성을 보였다. 일축압축강도($q_u$)는 점성 IGM에서 가장 중요한 변수이나, 화강풍화암 구간에서 직접 측정이 불가능하므로 정재하시험 및 하중전이시험 결과와 N값을 이용하여 $q_u$값을 얻을 수 있었다.

• Maxillofacial Plastic and Reconstructive Surgery
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• 제32권2호
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• pp.183-188
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• 2010

Leiomyosarcoma is a malignant neoplasm of smooth muscle origin and mostly originate from the wall of uterus and gastrointestinal tract, but primary leiomyosarcoma of the oral cavity is extremely rare. This tumor has a very poor prognosis due to high recurrence and metastasis rate, with 5 year survival rate of 32%. And regional lymph node metastasis is uncommon event. Complete wide surgical excision is the treatment of choice. A 64-year old man who had a painful ulcerative lesion on the labial & palatal gingiva of #11, 21 visited our department, and was diagnosed as leiomyosarcoma through a biopsy. Partial maxillectomy was carried out, with no following radiotherapy or chemotherapy. After months follow-up, there has been no evidence of recurrence or metastasis. But after months, we clinically find out two enlarged immobile palpable lymph node in right submandibular area of patient. So a biopsy was performed via an extraoral incision under local anesthesia. Histopathologic diagnosis diagnosis of the biopsy was lymph node metastasis of prior existed leiomyosarcoma. We report a case of a primary leiomyosarcoma occurred in a 64 year-old male patient involving the anterior maxillary region with regional lymph node metastasis with a review of literature.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2009년도 하계학술대회 논문집
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• pp.192-192
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• 2009

We have successfully demonstrated the inkjet printing process to fabricate $Al_2O_3$ thick films without a high temperature sintering process. A single solvent system had a coffee ring pattern after printing of $Al_2O_3$ dot, line and area. In order to fabricate the smooth surface of $Al_2O_3$ thick film, we have introduced a co-solvent system which has nano-sized $Al_2O_3$ powders in the mixture of Ethylene glycol monomethyl ester and Di propylene glycol methyl ether. This co-solvent system approached a uniform and dense deposition of $Al_2O_3$ powders on the substrate. The packing density of inkjet-printed $Al_2O_3$ films is more than 70% which is very high compared to the value obtained from the films synthesized by other conventional methods such as casting processes. The characterization of the inkjet-printed $Al_2O_3$ films has been implemented to investigate its thickness and roughness. Also the dielectric loss of the films has been measured to understand the feasibility of its application to 3D integration package substrate.

• 한국조경학회지
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• 제34권4호
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• pp.84-95
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• 2006

This study begins by examining the reason for the lack of urban planning that takes the water cycle into consideration. While there are institutions that support environmentally friendly development or smooth water circulation, these designs are not reflected in planning nor in the real world. After reviewing foreign case studies, policy suggestions and possible policy implications for Korea are derived. In Korea, there is not a sufficient level of relevant laws or institutions systematically established to make it possible to deal with rainwater in a decentralized way. Instead, facility standards or guidelines are considered separately for the control of water and for preventing natural disasters. And even though an environmentally friendly approach is stipulated in relevant laws in terms of spatial planning, there are no planning systems or implementation tools to actualize this kind of approach. The factors that make decentralized rainwater management possible in urban planning are analyzed based on the case study of Germany. Germany requires developers to plan in order to achieve ecological urban development. In addition, as a detailed implementation tool to promote conservation of the water cycle, the law provides for various kinds of measures such as restrictions on the proportion of impervious surface area according to the use of the land, required compensation measures for environmental degradation following development, introduction of a fee for rainwater runoff and the establishment of ecological landscape planning. The actual reason these measures can be implemented however is the provision of planning guidelines and design criteria for rainwater utilization, absorption and containment, and the construction of a database for various environmental information.

• 복식문화연구
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• 제9권4호
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• pp.616-628
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• 2001

The purpose of this research is to create a polyester sample book that serves as a point of reference that exporters in the Taegu area can allude to when exporting to the U.S. By getting this project off the ground, we can expect to make a worthy contribution to the manufacture of high-quality, value-added fashion & textile goods. The research was conducted as follows. First, a study was carried out in the local market ensued by consumer surveys with regards to consumer attitude on man-made fibers, market researches, and interviews with experts, all in conjunction with the Color Association of the U.S. Also, a diverse array of fabric swatches were collected from Manhattans fabric wholesalers and then classified by color and fabric type fur the sample book. In short, this research found that man-made fibers have full marketability in the U.S. Thus, in order for Taegus synthetic textile firms to be successful in exporting to the US, it is essential that they come up with fabrics that have properties resembling natural fibers such as having a soft hand, natural sheen, smooth draping, and diverse textures as well as being in line with the current trends. In addition, it is also necessary to develop fabrications that are versatile and functional. Thus, by developing innovative fabrications, the synthetic textile business will turn toward the production of high-quality synthetics and will also provide a platfrom for strengthening the competitive edge of Koreas textile & fashion business.

• Maxillofacial Plastic and Reconstructive Surgery
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• 제32권5호
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• pp.431-436
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• 2010

Purpose: It is estimated that the odontogenic keratocyst (OKC) makes up 10% to 12% of all developmen-tal odontogenic cysts. The lesion has been of particular interest because of its specific histopathologic fea-ture, high recurrence rate, and aggressive behavior. Materials and Methods: We investigated 266 OKCs of Korean patients for the sex of patient, the age of the patient, the location of OKC, the recurrence rate related to radiographic impression. Results: The male-to-female ratio was 1.47:1, showing a slight male predilection. Odontogenic keratocysts had a peak of occurrence in the third decade of life. The mandibular angle and ascending ramus area (49.6%) is the most frequent site of OKCs in the jaws. Fourteen cases of unilocular (12%) and 5 cases of multilocular (20%) OKCs recurred. Thirteen cases of smooth (12.9%) and 6 cases of lobulated (14.6%) OKCs recurred. Seventeen cases of OKCs without perforation of cortical bone (12.5%) and 2 cases of OKCs with perforation of cortical bone (33.3%) recurred. Fifteen people of patients with single lesion (12.2%) and 4 people of patients with multiple lesions (66.7%) recurred. Conclusion: In this resul, we consider multiple odontogenic keratocysts can recur more easily. So we have to treat them more carefully and need long-time follow-ups.

• 한국건축시공학회지
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• 제2권2호
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• pp.129-134
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• 2002

The strength and durability of concrete are affected by various factors such as the quality of material, mixing ratio, construction, the method of cure, time elapsed. the condition of test and etc., it is very difficult to pre-estimate the strength of concrete with the use of experimental specimen. The domestic standard of specimen cylindrical type and its sizes are both l0cm$\times$20cm and 15cm$\times$30cm, which are prescribed in KS F2405, and the loading speed is prescribed to test with 2~3kgf/$\textrm{cm}^2$ per second. The loading speed should have great effect on the compressive strength, but in reality in the construction site sometimes the loading speed is applied so dubiously that the value of the compressive strength can be unreliable. And the cross sectional area of a specimen should be level and smooth, otherwise it can be broken at a lower stress than the real strength through the eccentric or intensive working of the load. Capping should be carried out in order to measure the strength correctly. And used for capping are various materials such as capping compound, cement glue, plaster, mechanical grinding and etc. In this study, therefore, I have carried out an experiment on the relationship among the loading speed, the ratio of height to diameter of specimen, the method of capping, and the compressive strength, for the efficient quality control of concrete structures. So this study has been purposed to provide some basic data that can be used effectively at construction sites.