• Corrosion Science and Technology
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• v.18 no.3
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• pp.92-101
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• 2019

This study investigates how rivet head height affects the corrosion performance of carbon fiber reinforced plastic (CFRP) to aluminum alloy self-piercing riveted joints. Specimens with two different head heights were prepared. A rivet head protruding out of the top CFRP laminate forms the proud head height while a rivet head penetrating into the top CFRP generates the flush head height. The salt spray test evaluated corrosion performance. The flush head joints suffered from severe corrosion on the rivet head. Thus, the tensile shear load of flush head joints was substantially reduced. Electrochemical corrosion tests investigated the corrosion mechanisms. The deeper indentation of the flush head height damaged the CFRP around the rivet head. The exposure of damaged fibers from the matrix increased the cathodic potential of local CFRP. The increased potential of damaged CFRP accelerated the galvanic corrosion of the rivet head. After the rivet head coating material corroded, a strong galvanic couple was formed between the rivet head base metal (boron steel) and the damaged CFRP, further accelerating the flush rivet head corrosion. The results of this study suggest that rivet head flushness should be avoided to enhance the corrosion performance of CFRP to aluminum alloy self-piercing riveted joints.

• Journal of ILASS-Korea
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• v.20 no.3
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• pp.175-180
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• 2015

A series of sprinkler discharging tests was conducted to measure the droplet size and its distribution of residential fire sprinkler heads. Droplet sizes in sprinkler spray were measured using a laser diffraction method for the flush, circular and pendent type sprinkler head. In this study, the $D_{v,50}$ of the flush type sprinkler heads were ranged between $530{\sim}1040{\mu}m$ and those of circular and pendent type were $988{\mu}m$ and $916{\mu}m$, respectively. The measured cumulative volume distributions were followed by a combination of the log-normal and Rosin-Rammler distribution which is widely used in the computational fire analysis and the parameters of distribution function were obtained from the best fit line through the measured data.

• Journal of ILASS-Korea
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• v.28 no.2
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• pp.97-104
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• 2023

A sprinkler is a fire suppression system that extinguishes combustible materials in the early stages of a fire, creating a spray. However, spray formation method of the sprinkler can result in an uneven distribution of water spray on the surface of combustible materials. It is necessary to ensure a consistent water flux density regardless of the spray direction and angle. In this study, the water flux distribution was analyzed for the various types of sprinkler head: circular, flush, pendent, and upright types. All sprinkler heads have a K-factor of 80 LPM/(0.1MPa)^0.5. In this study, water collection cubes were used to examine the water flux distribution. The upright type sprinkler head showed a low standard deviation in total sprayed area, indicating a high level of uniformity. The upright type head showed the lowest standard deviation in the radial direction, and also showed the lowest standard deviation in the azimuthal direction. Upright sprinkler head has no obstructing structure along the path of droplets after they are generated. For this reason, upright sprinkler head showed the most uniform water flux distribution on the floor.

• Fire Science and Engineering
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• v.30 no.5
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• pp.26-35
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• 2016

Sprinkler installations shall be operated at normal operating temperature of the atmosphere as a fire sprinkler head in any facility to control and extinguish the fire when the fire initially. Recently, however, some flush type quick response automatic sprinkler heads in slow fire place is a problem that can not be normal operation are raised. In this paper, by using the experimental model of the Apartment house of Commons and Cabinet burner size bedrooms fire conditions to form a slow growth rate and can supply more than 0.2 MPa pressure is the minimum pressure that can be applied inside the pipe in the field experiment was conducted. In the majority of experiments lush type quick response automatic sprinkler heads which is used in the country it was confirmed to be incompletely opened as the Cold Soldering occur. This phenomenon is likely to fail early fire suppression and control because they can cause the spread of fire and casualties needed to complement domestic product testing and type approval standards through additional research.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.25 no.3
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• pp.150-159
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• 2015

An experimental study on frequency characteristics of the microphone array covered with Kevlar sheet was conducted in the closed test section. Microphones that were flush-mounted in the wall of wind tunnel were subjected to very high flow noise resulting from the turbulence in the wall boundary layer. This noise interference by the boundary layer was referred as 'a microphone self-noise' and various approaches were studied to reduce this interference. Recessed microphone array with high tensioned cover was one of the good approaches to reduce this self-noise. But, the array cover could cause an unexpected interference to the measuring results. In this paper the frequency characteristics of the microphone array with Kevlar cover was experimentally studied. The white noise was used as a reference noise source. Three kinds of tensions for the Kevlar cover were tested and those results were compared with the test results without the Kevlar cover. The gap effect between the cover and microphone head was also tested to find out the proper position of microphone in the array module. Test results show that the mid-tension and 10mm gap was the best choice in the tested cases.

• The Journal of Pediatrics of Korean Medicine
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• v.15 no.1
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• pp.235-253
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• 2001

Tae-yeul is the baby's disorder inheritted by its mother during fregnancy. This is due to its mother's overeating hot, fatty food and taking harmful medicine. So internal physical fever is accumulated in mother's body, and it heats up the placenta and the umbilical cord. Generally, this disorder means the skin disease that is occurred from $2{\sim}5$ months to 1 year after birth. It is specialized by the dirty oozing, a severe itching and the rash at its head and face. It is similar in its symptoms such as atopic dermatitis in western medicine. Recently, this disease has the increasing tendency of prevalence rate because of the bad atmosphere and the invironmental pollution. The results were summerised as follows; 1, 2, 3, 4 1. The causes of Tae-yeul are summarized by fragnat woman's contacting a cool air, overating a hot and toxic food and taking emotional shock. 2. The symptoms of Tae-yeul are the edema on upper eyelids, stifling convulsions, flush, the fever of one side body, the asthma of sputum increase, the yawing of the tired mind, the bowl complaint, the red urine and urination disturbance. 3. In the treatment method of Tae-yeul, its mother feed her milk after taking a madicine. So one must expect to be treated slowly. If one tries to treat it with a cool madicine quickly, it can cause vomitting or a serious disorder. 4. In the prescription of Tae-yeul, they used a Moktongsan, a Chiwhnagtang, an Yangyoubang, a Tojuksan, a Whangyunsan, a Juryungtang and a Kamdutang, etc.. For the method of cleaning face or bathing, they used Sasungsan, Whanbaekpijuntang. 5. Tae-yeul including Naesun, Taelyumchang, yousun, etc. is similar to the atopic dermatitis of western medicine in its symptoms.

• Journal of Korean Society of Environmental Engineers
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• v.37 no.3
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• pp.165-174
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• 2015

Non-point source pollution associated with suspended solids in stormwater has been known to often adversely affect surface water ecosystems. Various methods of treating stormwater in the basin area before the stormwater reaches the receiving body of water have been developed. However, these treatment methods tend to be costly to install and also to maintain. In this study, an economical way of removing TSS (total suspended solids) from stormwater runoff with a fabric filter system was developed. Polyester was chosen as a fabric-filter material, because it was found to be economical in cost and relatively resistant to various chemicals. An experimental device was developed and used to determine filtration rates through polyester fabric samples of a series of several pore-opening sizes ($20{\mu}m$ to $94{\mu}m$) under a series of water-heads (0.25 to 1 m). It was found that the filtration rate increased as the size of water head increased. It was also found that the smaller the pore size of the fiber filter was, the higher the TSS removal efficiency was. However, the TSS removal efficiency was not found to be much different among the filters with different sizes of pore opening due to the fact that most mass of TSS was associated with large particles.

• The Korean Journal of Nuclear Medicine Technology
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• v.16 no.2
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• pp.115-119
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• 2012

Purpose : The initial Breast-Specific Gamma Imaging (BSGI) protocol included bilateral breast imaging with 2 views of each breast-craniocaudal (CC) and mediolateral oblique (MLO). Furthermore, Axillary lymph nodes view can be acquired easily. The most meaningful prognosis factor for prediction of breast cancer is whether or not the breast cancer has metastasized to the lymph nodes. However, axillary view doesn't conduct in clinical. This article collates a diverse data of BSGI and describes technical details to acquire optimal imaging. Materials and Methods : A retrospective review was performed on 343 patients who had undergone BSGI between May 2011 and March 2012. Patients who had undergone BSGI received intravenous injection of 740 MBq (20 mCi) $^{99m}Tc$-sestamibi. Results : The following contents are the technical details for optimal axillary imaging. $^{99m}Tc$-sestamibi should be administered using an indwelling venous catheter or scalp needle followed by 10 cc of saline to flush to reduce extravasation and vascular trapping. After administration, patients raise their arm over their head and exercise with stress ball for 1 full minute. A lead shield attached to the gamma camera is removed and patients axilla is placed as close as possible to the camera at a $90^{\circ}$ angle. A lead apron is placed across the shoulder to reduce background from other organs. Acquisition time is enough for 120 sec~180 sec. Conclusion : If patients undergo bilateral axillary imaging as a standard with CC, MLO views, it could improve cancer treatment. Result of this study could maximize efficiency axillary imaging of breast cancer patients.