• Proceedings of the IEEK Conference
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• 2002.06b
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• pp.249-252
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• 2002

we have studied the characteristics of PHEMT's with gate recess etching method. The DC characterization of PHTMT fabricated with the wide single recess methods is a maximum drain current density of 319.4 ㎃/mm and a peak transconductance of 336.7 ㎳/mm. The RF measurements were obtained in the frequency range of 1~50GHz. At 50GHz, 3.69dB of 521 gain were obtained and a current gain cut-off frequency(f$_{T}$) of 113 CH and a maximum frequency of oscillation(f$_{max}$) of 172 Ghz were achieved from this device. On the other hand, a maximum drain current of 367 mA/mm, a peak transconduclancc of 504.6 mS/mm, S$_{21}$ gain of 2.94 dB, a current gain cut-off frequency(f$_{T}$) of 101 CH and a maximum frequency of oscillation(f$_{max}$) of 113 fa were achieved from the PHEMT's fabricated by the .narrow single recess methods.methods.

• Journal of Korean Neurosurgical Society
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• v.50 no.3
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• pp.264-267
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• 2011

A 50-year-old man presented bilateral hypesthesia on and below the T6 dermatome and paresthesia. Magnetic resonance imaging (MRI) showed an intraspinal extradural tumor, which located from the 6th thoracic vertebral body to the upper margin of the 7th vertebral body, continuing dumbbell-like through the intervertebral foramen into the right middle thorax suggesting a neurogenic tumor (neurofibroma or neurilemmoma). With the patient in a prone position, we exposed and excised the tumor via a one stage posterior approach through a hemi-laminictomy of T6. Histologic examination showed a grade 1 meningothelial meningioma, according to the World Health Organization classification. Initially, we assumed the mass was a schwannoma because of its location and dumbbell shape. However, the tumor was actually a meningioma. Postoperatively, hypesthesia resolved completely and motor power of the leg gradually full recovered. A postoperative MRI revealed no evidence of residual tumor.

• Clinical and Experimental Pediatrics
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• v.50 no.12
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• pp.1165-1172
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• 2007

Self/non-self discrimination and unresponsiveness to self is the fundamental properties of the immune system. Self-tolerance is a state in which the individual is incapable of developing an immune response to an individual's own antigens and it underlies the ability to remain tolerant of individual's own tissue components. Several mechanisms have been postulated to explain the tolerant state. They can be broadly classified into two groups: central tolerance and peripheral tolerance. Several mechanisms exist, some of which are shared between T cells and B cells. In central tolerance, the recognition of self-antigen by lymphocytes in bone marrow or thymus during development is required, resulting in receptor editing (revision), clonal deletion, anergy or generation of regulatory T cells. Not all self-reactive B or T cells are centrally purged from the repertoire. Additional mechanisms of peripheral tolerance are required, such as anergy, suppression, deletion or clonal ignorance. Tolerance is antigen specific. Generating and maintaining the self-tolerance for T cells and B cells are complex. Failure of self-tolerance results in immune responses against self-antigens. Such reactions are called autoimmunity and may give rise to autoimmune diseases. Development of autoimmune disease is affected by properties of the genes of the individual and the environment, both infectious and non-infectious. The host's genes affect its susceptibility to autoimmunity and the environmental factors promote the activation of self-reactive lymphocytes, developing the autoimmunity. The changes in participating antigens (epitope spreading), cells, cytokines or other inflammatory mediators contribute to the progress from initial activation to a chronic state of autoimmune diseases.

• Asian Pacific Journal of Cancer Prevention
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• v.17 no.11
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• pp.4907-4911
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• 2016

Glioblastoma multiforme (GBM) is the most aggressive of the gliomas, a collection of tumors arising from glia in the central nervous system. Possible associations between the human cytomegalovirus (HCMV) and the JC virus with GBM are now attracting interest. Our present aim was to investigate the prevalence of the two viruses in Iranian patients from Kerman's cities in the south of Iran. In addition, the expression rates of pp65, large T antigen and p53 proteins were assessed and their relation with GBM evaluated using reverse transcription real time PCR (rReal Time PCR). A total of 199 patients with GBM cancer were enrolled, with $mean{\pm}SD$ ages of $50.0{\pm}19.5$ and $50.7{\pm}19.6$ years for males and females, respectively. The P53 rate was dramatically low suggesting an aetiological role,. Large T antigen expression was found in JC positive samples, while the PP65 antigen was observed in patients positive for CMV and JC. HCMV products and JC virus with oncogenic potential may induce the development of various tumors including glioblastomas. The JC virus produces an early gene product, T-antigen, which has the ability to associate with and functionally inactivate well-studied tumor suppressor proteins including p53 and pRB.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.50 no.2
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• pp.169-175
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• 2014

The age and growth of rabbit fish, Siganus fuscescens were investigated from samples monthly collected in the coast of Jeju island, Korea from February to December 2012. Ages were determined from annuli in otoliths, and annuli were formed in one or two months immediately after spawning once a year. Also, main spawning period was estimated between July and August, thus rings were considered as annual marks. The von Bertalanffy growth equations estimated from a non-linear regression method were $L_t=37.24(1-e^{-0.33(t+1.24)})$ ($R^2=0.92$) for female and $L_t=31.44(1-e^{-0.45(t+1.23)})$ ($R^2=0.90$) for male, and the growth between female and male was different.

• Journal of Oriental Medical Thermology
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• v.3 no.1
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• pp.15-19
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• 2004

Cold hypersensitivity means a condition feeling cold at a temperature when one should not feel so. Cold hypersensitivity has been diagnosed based on the patient's subjective complaints. But these days, cold hypersensitivity can be diagnosed by the help of D.I.T.I.(Digital Infrared Thermal Imaging) This study is designed to verify the validity of diagnosis of cold hypersensitivity by D.I.T.I. Thermographic findings of 100 outpatients who visited the Kangnam Korean Hospital, KyungHee University, Seoul, Korea, from June 2000 to November 2000 were analyzed. The experimental group consisted of 50 patients who complained cold hypersensitivity, and for the control group, 50 patients who did not complain cold hypersensitivity. For the diagnosis of cold hypersensitivity of the hands, thermographic measurements were performed on two pairs of areas(palm-upper arm and back of hand-upper arm). And for that of the feet, other two pairs of areas(anterior thigh-top of the feet and posterior thigh-heel). When the criterion for thermal deviation between the palm and the upper arm was appointed as higher than $0.3^{\circ}C$, the sensitivity was 94.0% and the specificity, 90.0%. And when the criterion for that between the anterior thigh and the top of feet was appointed higher than $2.0^{\circ}C$, the sensitivity was 94.0% and the specificity, 76.0%. Through this study, the diagnostic standard for cold hypersensitivity of hands and feet could be presented.

• Proceedings of the KSME Conference
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• 2004.04a
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• pp.168-173
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• 2004

Fretting is a kind of surface degradation mechanism observed in mechanical components and structures. The fretting damage decrease in 50-70% of the plain fatigue strength. This may be observed in aircraft, automobile and nuclear power plant used in special environment and various loading conditions. In the present study, the characteristics of the fretting fatigue are investigated using the two aluminum alloy(Al2024-T3511 and Al7050-T7451). Through the experiment, it is found that the fretting fatigue strength of the Al7050-T7451 alloy decreased about 50% from the plain fatigue strength, while the fretting fatigue strength of the Al2024-T3511 alloy decreased about 45%. The tire track was widely observed in fracture surface area of oblique crack which was induced by contact pressure. These results can be the basic data to the structural integrity evaluation of aluminum alloy subjected to fretting damage.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.13 no.3
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• pp.23-35
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• 2010

A Sustainable Structured wetland Biotop (SSB) system was constructed on the floodplain of Kyungan stream in December, 2006. It purifies polluted water of Keumeo stream which flows into the stream. Water were sampled once a month at inlet and outlet from December, 2007 to December, 2008. $BOD_5$, SS, T-N and T-P were analyzed. Plant and fish species of the system were monitored twice during the period. Average influent and effluent BOD5 concentration was 6.2 and 2.2 mg/L, respectively and BOD5 removal was 50.8%. SS concentration of influent and effluent was averaged 10.1mg/L and 1.5mg/L, respectively and SS abatement amounted to 77.0%. Average influent and effluent T-N concentration was 4.9mg/L and 2.9 mg/L, respectively and T-N retention was 50.8%. T-P concentration of influent and effluent was averaged 0.386mg/L and 0.107mg/L, respectively and T-P removal amounted to 77.0%. Twenty two plant species were naturally introduced into the system, however, they didn't make up a significant portion of the plant populations compared with the planted species. Dominant plant species were in the following order; Phragmites communis > Typha latifolia > Iris pseudoacorus > Persicaria thunbergii. Five families and 15 species of fish were observed in the system including Chinese minnow (Moroco oxycephalus) which inhabits in clean water. Six more fish species were monitored in the system compared with ones living in Kyungan stream. Amphibia and reptiles accounted for 11 species of 4 orders and 7 families including Korean Salamander (Hynobius leechi) which also lives in cleanwater.

• Journal of the Korean Mathematical Society
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• v.50 no.5
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• pp.991-1008
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• 2013

In this paper, we mainly discuss Gorenstein Dedekind do-mains (G-Dedekind domains for short) and their overrings. Let R be a one-dimensional Noetherian domain with quotient field K and integral closure T. Then it is proved that R is a G-Dedekind domain if and only if for any prime ideal P of R which contains ($R\;:_K\;T$), P is Gorenstein projective. We also give not only an example to show that G-Dedekind domains are not necessarily Noetherian Warfield domains, but also a definition for a special kind of domain: a 2-DVR. As an application, we prove that a Noetherian domain R is a Warfield domain if and only if for any maximal ideal M of R, $R_M$ is a 2-DVR.

• Bulletin of the Korean Mathematical Society
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• v.50 no.2
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• pp.445-449
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• 2013

We consider a congruence ${\rho}$ on a group G as a subsemigroup of the direct product $G{\times}G$. It is well known that a relation ${\rho}$ on G is a congruence if and only if there exists a normal subgroup N of G such that ${\rho}=\{(s,\;t):st^{-1}{\in}N\}$. In this paper we prove that if G is a finitely presented group, and if N is a normal subgroup of G with finite index, then the congruence ${\rho}=\{(s,\;t):st^{-1}{\in}N\}$ on G is finitely presented.