• Journal of Korea Foundry Society
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• v.20 no.4
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• pp.254-259
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• 2000

Metal matrix composites(MMCs) reinforced with hard particles have many potential application in aerospace structures, auto parts, semiconductor package, heat resistant panels, wear resistant materials and so on. In this work, the effect of SiC partioel sizes(50 and 100 ${\mu}m$) and additional elements such as Si, Cu and Ti on the microstructure and the wear property of $Al-5Mg-X(Si,Cu,Ti)/SiC_p$ composites produced by pressureless infiltration method have been investigated using optical microscopy, scanning eletron microcopy(SEM) with EDS(energy dispersive spectrometry), hardness test, X-ray diffractometer(XRD) and wear test. In present study, the sound $Al-5Mg-X(Si,Cu,Ti)/SiC_p$(50 and 100 ${\mu}m$) composites were fabricated by pressureless infiltration method. The $Al-5Mg-0.3Si-O.1Cu-O.1Ti/SiC_p$ composite with $50 {\mu}m$ size of SiC particle has higher hardness and better wear property than any other composite with $100{\mu}m$ size of SiC particle produced by pressureless infiltration method. The hardness and wear property of $Al-5Mg/SiC_p$(50 and 100 ${\mu}m$) composites were enhanced by the addition of Si, Cu and Ti in Al-5%Mg matrix alloy.

• Journal of Korean Orthopaedic Sports Medicine
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• v.10 no.2
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• pp.105-108
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• 2011

Extra-skeletal chondroma, characterized by its lack of connection with the adjacent bone, includes synovial chondromatosis, intra-articular and para-articular chondroma, and soft tissue chondroma. Among them, the last two lesions are extremely rare. This is the case about 20-year-old soldier, who had complained of tenderness of the knee, pain and fullness during knee flexion and limitation of motion after a hard military training. We found a mass in the x-ray and MRI and resect the mass surgically, which was a $5.5{\times}4{\times}3$ cm size hard solitary mass. On microscopic finding, it was consisted of lobulated hyaline cartilage and outer fibrous capsule, and we ascertained it as para-articular chondroma. We experienced a case of para-articular chondroma in the infrapatellar fat pad of the knee joint and present its clinical, radiologic and pathologic findings with literature review.

• Journal of Korean Academy of Fundamentals of Nursing
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• v.6 no.3
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• pp.522-531
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• 1999

This research identifies the ingress to egress primary factors that causes a patient to receive delayed emergency medical care. This material was collected between February 1st to 28th, 1998. Research envolved 4,118 people who visited the college emergency medical center in Kyeongido Province, South Korea. Medical records were examined, using the retrospective method. to determine the length of stay and the main cause for waiting. Results are as follows : 1. The age group with the highest admission rate was 10 and under, approximately 1,394 (33.9%). Followed by an even distribution for ages between 11-50 at 10-15% for their respective ranges. The lowest admission rate was 50 years and above. 2. From the 4,118 records examined, 3,489 received outpatient treatment (84.7%); 601 were admitted for inpatient care (14.6%); 25 arrived dead on arrival (0.6%); and 4 people died at the hospital. 3. Between 7PM to 12AM, 42.9% were admitted to the EMC. The hours from 9PM to 11PM recorded the highest admission rate and 5AM to 8AM was the lowest From 8PM to 12AM, the most beds were occupied. 4. For most patients. the average length of stay was approximately 2.2 hours. By medical department, external medicine was the longest for 2.8 hours. Pediatrics was the shortest for 1.6 hours. The average waiting period for inpatient admission was 2.6 hours. Inpatient admission for pediatrics and external medicine was 3.4 hours and 2.2 hours respectively. 5. Theses are primary factors for delay at EMC: 1) pronged medical consultations to decide between inpatient versus outpatient treatment, and delaying to be inpatient, 2) when you call physicians they are delayed to come 3) Understaffing during peak or critical hours, 4) Excessive consulting with different medical departments, 5) some patients require longer monitoring periods, 6) medical records are delayed in transit between departments, 7) repeated laboratory tests make delay the result, 8) overcrowded emergency x-ray place causes delay taking x-ray and portable x-ray, 9) the distance between EMC and registration and cashier offices is too far. 10) hard to control patient's family members. The best way to reduce EMC waiting and staying time is by cooperation between departments, both medical and administrative. Each department must work beyond their job description or duty and help each other to provide the best medical service and satisfy the patient needs. The most important answer to shortened the EMC point from ingress to egress is to see things from a patient point of view and begin from there to find the solution.

• Korean Journal of Heritage: History & Science
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• v.47 no.1
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• pp.164-179
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• 2014

The Buddhas of the Three Words in a form of arranging Bhaiṣajyaguru and $Amit{\bar{a}}bha$ at its side based on ${\acute{S}}{\bar{a}}kyamuni$ at the center is enshrined in Daeungbojeon Hall of Daeheungsa Temple located at Haenam. So far, this Buddhas of the Three Words has been known as a wooden Buddha statue. However, as a result of X-ray screening, in left/right Buddha statues excepting main Buddha, wood and molding clay layer were observed at the same time. Therefore, this study intended to observe its internal structure, grafting method and to clarify making technique of Buddha statue during Joseon era based on image information being obtained through X-ray screening of The Buddhas of the Three Words of Daeheungsa Temple. As its result, it was revealed that form of ${\acute{S}}{\bar{a}}kyamuni$ was completed by mainly grafting 5 pieces of timber and this statue shows a typical wood grafted Buddha statue during Joseon era. Form of Bhaiṣajyaguru and $Amit{\bar{a}}bha$ were completed based on molding technique by applying clay on sculpture similar to its appearance after sculpturing more than 10 pieces of timber through its grafting. In other words, internal timber is considered to play a role of its core and grafting method of timber is more close to a technique of molding Buddha statue than to that of wooden Buddha statue during Joseon era. However, clay was directly applied on timber thinly, not applying clay thickly on it after winding straw rope on wooden core and its characteristic is that its facial area was completely composed of wooden construction only. Therefore, it is hard to rule out a possibility that the original sculpturing intention of an artist might be a wooden Buddha statue but in view of the fact that a word, 'molding' was used in a record of relics buried in statue, it could be seen that this Buddha statue might have been recognized as a molding statue at the time when creation of this statue was completed. It is considered that number of case of making statue based on this technique would be more increased when more results of X-ray screening should be accumulated and if more data should be collected, it would provide a significant evidence for identifying chronological, regional aspects of making technique of Buddha statue.

• Journal of the Microelectronics and Packaging Society
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• v.22 no.3
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• pp.45-50
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• 2015

The goal of this research is the create novel magnets with no rare-earth contents, with larger energy product by comparison with currently used ferrites. For this purpose we developed nano-sized hard-type/soft-type composite ferrite in which high remanent magnetization (Mr) and high coercivity (Hc). Nano-sized Ba-ferrite, Ni-Zn ferrite and $BaFe_{12}O_{19}/Ni_{0.5}Zn_{0.5}Fe_2O_4$ composite ferrites were prepared by sol-gel combustion method by use of glicine-nitrate and citric acid. Nanocomposite ferrites were calcined at temperature range $700-900^{\circ}C$ for 1h. According to the X-ray diffraction patterns and FT-IR spectra, single phase of NiZn-ferrite and Ba-ferrite were detected and hard/soft nanocomposite ferrite was indicated to the coexistence of the magnetoplumbite-structural $BaFe_{12}O_{19}$ and spinel-structural $Ni_{0.5}Zn_{0.5}Fe_2O_4$ that agreed with the standard JCPDS 10-0325 data. The particle size of nanocomposite turn out to be less than 120 nm. The nanocomposite ferrite shows a single-phase magnetization behavior, implying that the hard magnetic phase and soft magnetic phase were well exchange-coupled. The specific saturation magnetization ($M_s$) of the nanocomposite ferrite is located between hard ($BaFe_{12}O_{19}$) and soft ferrite($Ni_{0.5}Zn_{0.5}Fe_2O_4$). The remanence (Mr) of nanocomposite ferrite is much higher than that of the individual $BaFe_{12}O_{19}$ and $Ni_{0.5}Zn_{0.5}Fe_2O_4$ ferrite, and $(BH)_{max}$ is increased slightly.

• Journal of the Korean Magnetics Society
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• v.13 no.1
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• pp.1-5
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• 2003

Magnetic and structural properties of $(CoFe_2O_4)_{1-x}(Y_3Fe_5O_{12})_x$ powders (0 $\leq$ x $\leq$ 1) grown by a conventional ceramic method were investigated using X-ray diffractormeter (XRD), scanning electron microscopy (SEM), Mossbauer spectroscopy and vibrating sample magnetometer (VSM). The XRD results for the powders annealed at 120$0^{\circ}C$ indicated that no other peak was observed except for the ones from cobalt ferrite and the garnet powder. SEM micrographs indicated that cobalt ferrite and garnet powders were aggregated and completely formed together. It was hard to identify which part of the powders was the garnet or the cobalt ferrite. Mossbauer spectra for powders grown separately and mixed mechanically consisted of sub-spectra of cobalt ferrite and garnet, however, powders annealed together had an extra sub-spectrum, which was related with the interaction between iron ions at the grain surfaces of cobalt ferrite and the garnet: cobalt ferrite and garnet particles were located very closely. The value of the saturation magnetization measured by a VSM as a function of composition ratio agreed very well with the ones based on the theoretical calculation.

• Archives of Plastic Surgery
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• v.37 no.3
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• pp.281-284
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• 2010

Purpose: Pseudohypoparathyroidism is a hereditary disorder characterized by symptoms and signs of hypoparathyroidism, typically in association with distinctive skeletal and developmental defects. Hypoparathyroidism is caused by a insufficient end-organ response to PTH (parathyroid hormone). Hypoparathyroidism consists of four types in which the most common form, pseudohypoparathyroidism-Ia, accompany with Albright's hereditary osteodystrophy. We experienced a case of a woman who had been suffering from calcified mass on left foot, diagnosed Albright's hereditary osteodystrophy. Methods: We present a case of a 24-year-old Korean female who visited plastic surgery department with a painful mass on dorsum of the left foot. On the physical exam, bony hard and painful mass, fixed to dermis, was noted. Plain X-ray films demonstrate suspicious calcification on subcutaneous tissue of dorsum of the left foot. The patient was diagnosed pseudohypoparathyroidism 2 years ago at the plastic surgery department. At the visiting time, the laboratory results were within normal range even though the patient actually had a disease. The reason is because the patient has been treated with Vit.D, calcium replacement therapy and thyroid hormone therapy. Moreover, the patient has been treated with anticonvulsant agents due to epilepsy. On the brain computer tomography (CT), calcification was noted on the basal ganglia and dentate nucleus. So we decided the total excision of entire mass from the left foot. Results: We excised main mass with numerous pinhead sized masses which were scattered around the main mass. The $6.0{\times}4.0{\times}0.5\;cm$ sized main mass was bony hard, and its surface was flat and margin was irregular. The permanent biopsy was confirmed that the main mass and all the scattered tiny masses were heterotopic calcification. The patient did not suffer from the pain after the mass excision. The wound has been healed without any problem. Conclusions: Heterotrophic calcification is often accompanied with pseudohypoparathyroidism, but such a huge one is uncommon. We report a case of pseudohypoparathyroidism with heterotrophic calcification developed in dorsum of left foot who was diagnosed by excisional biopsy.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.38 no.6
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• pp.629-636
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• 2014

For surface modification, bulk metallic glass coatings were fabricated using metallic glass powder and a mixture of a self-fluxing alloy or/and hard metal alloys with a heat-resisting property using a high velocity oxy-fuel coating thermal spraying process. Microstructural analyses and mechanical tests were carried out using X-ray diffraction, a scanning electron microscope, an atomic force microscope, a three-dimensional optical profiler, and nanoindenation. As a result, the monolithic metallic glass coating was found to consist of solid particle and lamellae regions that included many pores. Second phase-reinforced composite coatings with a self-fluxing alloy or/and hard metal alloy additives were employed with in-situ $Cr_2Ni_3$ precipitate or/and ex-situ WC particles in an amorphous matrix. The mechanical behaviors of the solid particles and lamella regions showed large hardness and elastic modulus differences. The mechanical properties of the particle regions in the metallic glass composite coatings were superior to those of the lamellae regions in the monolithic metallic glass coatings, but indicated similar trends in matrix region of all the coating layers.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.02a
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• pp.200-200
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• 2013

기존 메모리 반도체에 비교해 빠른 재생속도와 높은 집적도, 비휘발성 등의 특성을 가지는 MRAM (Magnetic Random Access Memory)은 DRAM, flash memory 등을 대체할 수 있는 차세대 기억 소자로서 CoFeB/MgO/CoFeB로 구성된 한 개의 MTJ (Magnetic Tunnel Junction)를 단위 메모리로 사용한다. 이 MTJ 물질들은 고밀도 플라즈마를 이용한 건식 식각공정시 Cl2, BCl3 등과 같은 chlorine 을 포함한 가스를 이용하여 왔으나 식각 후 sidewall에서 발생하는 부식과 식각 선택비 확보의 어려움 등으로 마스크 물질에 제약을 받고 소자 특성이 감소하게 되는 등의 문제가 있다. 따라서 이러한 식각 문제점을 해결하기 위한 대안으로 noncorrosive 가스인 CO/NH3, CH3OH, CH4 등을 이용한 MTJ 식각 연구가 진행되어 오고 있으며 이중 CO/NH3 혼합가스는 부식성이 없고 hard mask와의 높은 선택비를 가지는 기체로 CO gas에 NH3 gas를 첨가하게 되면 etch rate이 증가하는 특성을 보인다. 또한 rf pulse-biased power를 이용하여 이온의 입사를 시간에 따라 제어함으로써 pulse off time 때 etch gas와 MTJ 물질간의 chemical reaction을 향상시킬 수 있다. 따라서 본 연구에서는 CO/NH3 혼합가스를 이용하여 다양한 rf pulse-biased power 조건에서 MTJ 물질인 CoFeB, MgO와 hard mask 물질인 W을 식각 한 뒤 식각특성을 분석하였으며 MTJ surface의 chemical binding state, surface roughness 측정을 진행하였다. 식각 샘플의 측정은 Alpha step profiler, XPS (X-ray Photoelectron Spectroscopy), AFM (Atomic Force Microscopy)를 통해 진행되었다. Time-averaged pulse bias에서는 duty ratio가 감소할수록 etch rate의 큰 감소 없이 CoFeB/W, MgO/W 물질의 etch selectivity가 향상됨을 확인할 수 있었으며 pulse off time 구간에서의 chemical reaction 향상으로 인해 식각부산물의 재증착이 감소하고 CoFeB의 surface roughness가 감소하는 것을 확인하였다.

• Fibers and Polymers
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• v.2 no.2
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• pp.98-107
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• 2001

The phase transition behavior isothermal micro-phase separation kinetics of polyester-based thermoplastic elastomer were studied using the synchrotron X-ray scattering(SAXS) method. The structural changes occurring during heating period were investigated by determining the changes of the one-dimensional correlation function, interfacial thickness and Porod constant. Based on the abrupt increases of the domain spacing and interfacial thickness, a major structural change occurring well below the melting transition temperature is suggested. Those changes are explained in terms of melting of the thermodynamically unstable hard domains or/and the interdiffusion of the hard and soft segments in the interfacial regions. SAXS profile changes during the micro-phase separation process were also clearly observed at various temperatures and the separation rate was found to be sensitively affected by the temperature. The peak position of maximum scattering intensity stayed constant during the entire course of the phase separation process. The scattering data during the isothermal phase separation process was interpreted with the Cahn-Hilliard diffusion equation. The experimental data obtained during the early stage of the phase separation seems to satisfy the Cahn-Hilliard spinodal mechanism. The transition temperature obtained from the extrapolation of the diffusion coefficient to zero value turned out to be about 147$\pm$$2^{\circ}$, which is close to the order-disorder transition temperature obtained from the Porod analysis. The transition temperature was also estimated from the inveriant growth rate. By extrapolating the inveriant growth rate to zero, a transition temperature of about 145$\pm$$\pm$$2^{\circ}$ was obtained.