• ETRI Journal
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• v.27 no.3
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• pp.304-311
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• 2005

We report on the fabrication of an AlGaAs/InGaAs/GaAs pseudomorphic high electron mobility transistor (PHEMT) using a dielectric-defined process. This process was utilized to fabricate $0.12\;{\mu}m\;{\times}\;100 {\mu}m$ T-gate PHEMTs. A two-step etch process was performed to define the gate footprint in the $SiN_x$. The $SiN_x$ was etched either by dry etching alone or using a combination of wet and dry etching. The gate recessing was done in three steps: a wet etching for removal of the damaged surface layer, a dry etching for the narrow recess, and wet etching. A structure for the top of the T-gate consisting of a wide head part and a narrow lower layer part has been employed, taking advantage of the large cross-sectional area of the gate and its mechanically stable structure. From s-parameter data of up to 50 GHz, an extrapolated cut-off frequency of as high as 104 GHz was obtained. When comparing sample C (combination of wet and dry etching for the $SiN_x$) with sample A (dry etching for the $SiN_x$), we observed an 62.5% increase of the cut-off frequency. This is believed to be due to considerable decreases of the gate-source and gate-drain capacitances. This improvement in RF performance can be understood in terms of the decrease in parasitic capacitances, which is due to the use of the dielectric and the gate recess etching method.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.11 no.2
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• pp.443-448
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• 2010

Rapid advance in information technology requires high performance devices with compact size. Integrated multi-layer electronic element with different functions enables those compact devices to possess various performances and powerful capabilities. In mass production, the multi-layer electronic element is manufactured as a bulk type with a large number of parts for productivity. However, this may cause the electronic part to be damaged in the cutting process of the bulk elements to separate into each part. Therefore the cutting performance of multi-layer element bulk is playing an important role in the view of production efficiency. This study focuses on the cutting characteristics of multi-layer electronic elements. In order to increase the efficiency, the vibration cutting method was applied to the blade cutting machine. Flexure hinge structure, which is an physical amplifier of increasing displacement, was attached to the vibration cutting device for machining efficiency. The behaviors of flexure hinge were modeled with Lagrange equation and simulated with finite element method (FEM). Performance of hinge structure was verified by experimental modal analysis (EMA) for hinge structure to be tuned to the specific mode of vibrations. Cutting experiments of multi-layer elements were conducted with the proposed vibrating cutting module, and the characteristics was analyzed.

• Corrosion Science and Technology
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• v.3 no.2
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• pp.59-66
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• 2004

In construction of new ships and large steel bridges in Korea, pre-construction primers (PCP), also known as shop primer, are routinely used and retained as an integral part of the protective coating system. Retention of PCP's can significantly reduce building schedule and cost. Retaining PCP through the so-called "sweep blasting" procedure eliminates or minimizes the necessity of a second blast operation, thus shortening overall schedule as well as reducing labor cost and hazardous waste disposal cost. This study evaluates the feasibility of retaining PCP as the part of primer for high performance protective coating systems applied to ships' hull, bottom and ballast tanks. Upon proving that the retention of the PCP is a viable option, the process of coating application can he improved significantly in terms of cost and working schedule of new ships and large steel bridges. Results indicate that use of the PCP via sweeping blasting in conjunction with standard high performance protective coating systems does not degrade the overall performance of the coating systems. At the same time, it is also highly recommended that the secondary surface preparation should consist of grit blasting of weld burnt and other damaged areas to SSPC SP-IO grade (Sa 2.5 Gr.), Near White Blast Cleaning with proper application and attention to detail.

• Journal of Acupuncture Research
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• v.19 no.6
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• pp.1-11
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• 2002

Objective : Korean medicine treatment method is noted as alternative in treating traffic accidents(TA) victims recently. The main purpose of this research is to make a survey of the effective way of the Korean medicine treatment about TA victims. Methods : In following research, 389 cases of traffic victims who hospitalized in the Youngsaeng Korean Medicine Hospital & Youngsaeng Clinic from March 1, 2001 to November 30, 2001 were surveyed. The research is focused on finding out the distribution, such as sex and age, damaged part of the body of 389 TA victims, nature of damage of 389 TA victims, chief complaint of 389 TA victims, nature of damage by Korean medicine code classification, treatment given to 389 TA victims, Extract(Ex) medicine given to 389 TA victims, days in hospital of 389 TA victims. Results : The patients reached korean medicine hospital in fewer numbers from most of TA victims. As neck pain and L-spin sprain, most of symptoms was light and the treatment of medicine as well was limited for TA. The treatment method which was used for treating TA was acupuncture, cupping therapy, physical therapy, Ex medicine. Few ways could use the Ex medicine as well. Conclusions : The achieving rate of treatment was marked highly by using Haenggi(行氣) Hwalhyeol(活血) Guyea(祛瘀) and we confirmed a possibility for the treatment of TA in korean medicine treatment method. It needs to increase all kinds of treatment-ways which can treat successfully and needs to come into application of insurance. Korean medicine method will have possibility to take part in TA injury admission, by presenting basis to prove effectiveness of treatment-ways.

• Journal of Welding and Joining
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• v.23 no.6
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• pp.49-54
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• 2005

Inner Structured and Bonded(ISB) panel, a kind of metallic sandwich panel, consists of two thin skin plates bonded to a micro-patterned inner structure. Its overall thickness is $1\~3mm$and it has attractive properties such as ultra-lightweight, high efficiency in stiffness-to-weight and strength-to-weight ratio. In many previous studies, resistance welding, brazing and adhesive bonding are studied for joining the panel. However these methods did not consider productivity, but focused on structural characteristics of joined panels, so that the joining process is very complicated and expensive. In this paper, a new joining process with resistance welding is developed. Curved surface electrodes are used to consider the productivity and the stopper is used between electrodes during welding time to maintain the shape of inner structure. Welding time, gap of electrodes and distance between welding points are selected as the process parameters. By measuring the tensile load with respect to the variation of welding time and gap of electrodes, proper welding conditions are studied. Welding time is proper between 1.5-2.5cycle. If welding time is too long, then inner structures are damaged by overheating. Gap of electrode should be shorter than threshold value fur joint strength, when total thickness of inner structure and skin plate is 3.3mm, the threshold distance is 3.0mm.

• Korean journal of applied entomology
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• v.47 no.1
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• pp.107-110
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• 2008

Tropical fire ant, Solenopsis geminata (Fabricius) is distributed over the tropical and temperate areas. It is a polyphagous pest attacking to various plant and causes the pain to the people doing outdoor work. So it is known for a hygienic pest to human being, especially the people doing outdoor activities. It can cause severe pain to human, even with just a bite. Of particular concern is the possibility of its settlement in this country, if it invade to the farmlands and/or forests of Jeju Island and southern part in Korea. It is listed as a regulated pest in Plant Quarantine Act of Korea. This ant is usually imported through a ship and early settled in the port area where it is already distributed. Recently its distribution is rapidly spreading into Southeast Asia and southern part of China. In Korea, it was detected the one time in 1990s, but was detected the ten times from 2000 to 2006 by an imported plant quarantine process. Therefore, we would like to provide some information on the species, including morphology, distribution, host plant, damaged symptom and its general bionomics, which will be useful data for plant quarantine process and control.

• Journal of Conservation Science
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• v.29 no.1
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• pp.35-45
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• 2013

The Clay Statues of Donggwanwangmyo Shrine (Treasure No. 142) are highly damaged physical weathering which are crack, exfoliation. Pigment of surface are discolored by chemical weathering like dust. The result of ultrasonic velocity measurement, low velocity zone was measured the lowest part of Woojanggun Statue. Deficiency condition of pigment layer was evaluated quantitatively through infrared Thermography. As a result, exfoliation part was detected at high temperature. Making techniques of the Clay statues were identified by gamma rays, infrared TV, SEM. All Clay Statues were founded on wood base and joints of wood were fixed using thin iron wires. After wood base was twisted a straw rope, it was made by clay. Clay was blended with rice straw to prevention of crack and exfoliation. The upper side of clay layer was coated with Hanji(Korean handmade paper) and cotton in order to isolate the pigment layer.

• Korean Journal of Pharmacognosy
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• v.37 no.1 s.144
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• pp.28-32
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• 2006

Hepatoprotective effects of an aqueous extract prepared from the aerial part of Agrimonia eupatoria L., a species of agrimmony, were investigated in experimental liver-damaged models. To investigate hepatoprotective effects, the agrimmony extract were fed orally to experimental animals. Thereafter a single dose of hepatotoxin, carbon tetrachloride $(CCl_4)$ or D-galac-tosamine was orally administrated. Chronic liver damage was induced by oral administration of $CCl_4$ for 2 weeks (1 time/day). Hepatoprotective effects were monitored by estimating serum AST and ALT levels. The results showed that the agrimmony extract significantly reduced AST and ALT levels compared with those of control group in both acute and chronic animal models. It was concluded that the agrimmony extract have hepatoprotective effects against rat liver injury induced by $CCl_4$ or D-galactosamine.

• Korean Journal of Heritage: History & Science
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• v.49 no.4
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• pp.52-63
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• 2016

The Stupa of Buddhist Monk Soyo in Baegyangsa temple, Jangseong, was erected to pay a tribute to the achievement of the Buddhist monk Soyo, who worked for Baegyangsa temple as a chief monk, and is a bellshaped stupa with the detailed pattern of a Korean traditional buddhist bell. It is composed of pinkish-grey sandstone and the body of the stupa was damaged by longitudinal cracks on the front and back areas and the exfoliation caused break-out in the most part of the sculpture on the left and right areas. According to the ultrasonic test and infrared thermography analysis for physical deterioration diagnosis, most weathering aspects appeared on the body of the stupa and some exfoliated part that could not be seen with the naked eye was detected 6.1% and 5.9% on the left and right side respectively. Hyperspectral imaging analysis was also carried out to assess biological deterioration. According to the result, the surface of the stupa was covered 71.8 ~ 79.9% with vegetation like algae, lichen and moss. NDVI(Normalized Difference Vegetation Index) was higher relatively on the bottom part near the ground, right and back areas of the stupa. Therefore conservation treatment for the exfoliated part and bio-deterioration is necessary and the environment condition needs to be fixed to prevent extra damages on the stupa.

• Journal of Environmental Policy
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• v.5 no.4
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• pp.1-18
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• 2006

Recently, the damage by fresh flood increases in Gangwon-do and Gyeongsangbuk-do of the north-eastern area of Korea. Even though the recent pattern of rain fall keeps changing, there is no strategy to mitigate damage by disaster. For the appropriate measure and policy for decreasing damage, an index for vulnerability is necessary to provide evidence of local climate change. The present work analyzes the flooding damage cost during the past 20 years. During 80's, the southern area of Korea was seriously damaged by over-floods on the agricultural ground. After that time, the loss and damage has decreased in the southern area but the middle part has shown slight but distinct increases of damage. The absolute coast of damage in the northern part has kept constant. However, the relative regional damage to the total country damage has kept increasing over 20 years in the same area. The surface area of floods is strongly correlated with the regional damage cost in the southern part but the north-eastern part has weak correlation between flooded area and cost. It implies that the recent damage in the north-eastern mountain area was not caused by flood itself but the other factors such as avalanches. The present work expects that the damage cost can be a good proxy value for index for climate change impact assessment.