• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.17 no.3
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• pp.139-148
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• 2012

The short-term variation of salinity and temperature in a dyked estuarine environment is mainly controlled by the freshwater discharge from the dyke. We examined the distribution of salinity and temperature by the freshwater discharge in the Yeongsan River estuary using the CTD data obtained from 8 stations through three surveys in June (weak discharge) and August (intensive discharge), 2010. During the weak discharge in June, the surface salinity showed 30-32.5 psu and its horizontal gradient was relatively high around Goha-do (0.25~0.32 psu/km). On the other hand, the salinity of the bottom layer was almost constant in the range of 33 psu. Water temperature ranged $19{\sim}21^{\circ}C$ and displayed higher gradient in north-south direction than the gradient of east-west direction. During the intensive freshwater discharge on August 12, the salinity dropped to 9~26 psu. The maximum horizontal gradient of surface salinity reached 3.8 psu/km in the north of Goha-do where the strong salinity front was formed, and the horizontal salinity gradient of bottom layer was 0.28 psu/km. The horizontal gradient of water temperature was $-0.45^{\circ}C/km$ in the surface and $-0.12^{\circ}C/km$ in the bottom with high surface temperature near the dyke and decreasing gradually to the river mouth. After 3 days of the intensive discharge ($3^{rd}$ survey), the surface salinity increased to 22~26 psu. However, there still existed relatively high horizontal gradient around Goha-do. In the mean time, the bottom salinity decreased to 26.5~27.5 psu, but its gradient was not big as much as the surface gradient. According to time series of CTD profile near the dyke, the discharged fresh water jetted down temporarily and then recovered gradually with the recovering speed of 0.4 m/hour for the discharge case of $13{\times}10^6$ ton. Due to the combined effects of freshwater discharge and surface heating during the summer of 2010, the Yeongsan estuary, in general, underwent intensified vertical stratification, which in turn caused the inhibition of vertical mixing, especially inside area of estuary. Based on the spatial distribution of salinity and temperature, the Yeongsan estuary can be divided into three regions: the Goha-do area with strong horizontal gradient of salinity and temperature, inner estuary from Goha-do to the dyke with low salinity, and outer estuary from Goha-do to the coasts with relatively high salinity.

• Journal of Animal Environmental Science
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• v.9 no.2
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• pp.103-112
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• 2003

In this study, the distributions of internal climates such as air temperature, humidity, dust, ammonia gas, and air velocity were systematically measured at a mechanically ventilated broiler houses during summer season, with local weather data. The analysis was focused on the suitability, stability, and uniformity of internal climate, resulting in serious stress on chickens and decrease of productivity In the mechanically ventilated broiler house, the difference between measured and recommended air temperatures(suitability) was 10.4C in maximum during the summer time. The difference of air temperature in the house between day and night was $8.7^{\circ}C$ in maximum. And maximal hourly range of internal air temperature at 0.4m height from the floor was $3.7^{\circ}C$ suggesting it maintained thermal uniformity in the broiler house. The $NH_3$ and dust concentrations were pretty low because ventilation was fully performed. The air speed at chicken location was measured 2.2m/s and 1.7m/s, respectively without and with chicken existence.

• Journal of the Korea Society of Computer and Information
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• v.24 no.12
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• pp.51-57
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• 2019

In this paper, we analyzed the performance of IoT based smart wearable mine detection device. There are various mine detection methods currently used by the military. Still, in the general field, mine detection is performed by visual detection, probe detection, detector detection, and other detection methods. The detection method by the detector is using a GPR sensor on the detector, which is possible to detect metals, but it is difficult to identify non-metals. It is hard to distinguish whether the area where the detection was performed or not. Also, there is a problem that a lot of human resources and time are wasted, and if the user does not move the sensor at a constant speed or moves too fast, it is difficult to detect landmines accurately. Therefore, we studied the smart wearable mine detection device composed of human body antenna, main microprocessor, smart glasses, body-mounted LCD monitor, wireless data transmission, belt type power supply, black box camera, which is to improve the problem of the error of mine detection using unidirectional ultrasonic sensing signal. Based on the results of this study, we will conduct an experiment to confirm the possibility of detecting underground mines based on the Internet of Things (IoT). This paper consists of an introduction, experimental environment composition, simulation analysis, and conclusion. Introduction introduces the research contents such as mines, mine detectors, and research progress. It consists of large anti-personnel mine, M16A1 fragmented anti-mine, M15 and M19 antitank mines, plastic bottles similar to mines and aluminum cans. Simulation analysis is conducted by using MATLAB to analyze the mine detection device implementation performance, generating and transmitting IoT signals, and analyzing each received signal to verify the detection performance of landmines. Then we will measure the performance through the simulation of IoT-based mine detection algorithm so that we will prove the possibility of IoT-based detection landmine.

• Korean Journal of Environment and Ecology
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• v.27 no.6
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• pp.676-689
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• 2013

This study is to understand the current situation of Wonju Stream, which flows through Wonju, Kangwon-do, and Seom River, the national river located outside of Wonju, by investigating all river areas using biotope type. Also, this research looked into the relationship between biotope and appearance of wild birds by investigating the location of their appearance. Biotope groups are 'scale', 'shape', and 'landscape'. And, biotope types are 'moisture', 'physical environment', and 'existence of vegetation'. Biotope subtypes are 'river area', 'physical environment', 'vegetation type', and 'usage of land'. Seom River is classified as 21 different sections, and Wonju Stream is classified as 19 different sections. Wild birds are investigated on breeding season, which was January and May of 2008. By marking each bird's location of appearance, it figured out properties of biotope according to the location of bird's appearance. 31 species, 795 birds in spring were founded, and 49 species, 4,348 birds are founded in winter at Seom River area. Also, 34 species, 427 birds in spring, and 33 species, 3,442 birds are founded in winter at Wonju Stream area. In winter, 26 species, 547 birds, and in spring, 12 species, 72 birds at natural river with estuaries in confluence of Seom River area are founded. Also, 34 species, 1412 birds in winter, and 24 species, 341 birds in spring are founded at natural river with estuaries and wetland plants. This means that because agricultural rivers have wide river width, slow flow speed, and many different types of biotope, these rivers can be good habitats for wild birds. The precise investigations and classifications of biotope, which especially are hard for linear rivers, were done to understand the whole and current situation of rivers. Furthermore, the data that shows the locations of wild birds can basically be used for a recovery of biological habitats, a constructing of ecological streams, a river-maintenance, and an enhancement of biodiversity of Wonju. Also, because the types of biotope are altered by rain, a continuous monitoring for maintaining ecosystem of rivers are highly needed.

• Archives of design research
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• v.17 no.4
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• pp.241-250
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• 2004

In this research, the copper alloy plates C2200, C5210, C7701, C8113 were selected to make datum and to identify further usage of metal craft experimentation. For its experimentation, the general welding and TIG welding methods were researched; for 2nd experimentation, the Reticulation and Electroforming skill's differences in color and temperature were researched. With these methods 3 different kinds of works are introduced for sample studies. For this research, Dr. Lee, Dong-Woo who works in Poongsan Metal Co, supported 4 kinds of copper alloy metals. Which are Commercial bronze (Cu-Zn), Deoxidiged Copper(Cu-Sn-P), Nickel Silver (Cu-Ni-Zn), and White Bronze (Cu-Ni); they were applied partly and wholly by the method of Laminatin, Reticulation, Fusing, and Electroforming skills. In case of C2200, the brass, the A. C. TIG welding method is better under 2mm slight plate; the D.C. TIG welding is better upper 2mm plate; and 250~300$^{\circ}C$ is recommended for remain heat treatment. In case of C5210, not having Hydrogen in high temperature return period, doesn't need Oxygen in high temperature and hardening in comparative high temperature neither, it is good for welding. It contains Sn 2-9% ad P 0.03-0.4% generally; and in accordance with the growth rate of Sn contain amount, the harden temperature boundary become broad. In case of cold moment after welding, they are recommended that higher speed TIG welding, smaller melting site and less than 200$^{\circ}C$ for pre-heating temperature. In case of C7701, the 10-20% Ni, 15-30% Zn are widely used.. If it is upper 30% Zn, it become (${\alpha}+{\beta}$) system and adhesive power rate become lower, and the productivity become lower in low temperature but the productivity become higher in high temperature. Nickel Silver's resistance of electricity is well; and the heatproof and incorrodibility is good, too. Lastly, in case of C8113, good at persistence in salty and grind; high in strength of high temperature. In case of white brass, contain 10-30% Nickel and hardened in high temperature and become single phrase. For these reason, the crystallization particles easily become large, if the resistance become higher small amount of Pb, P, S separation rate become higher.

• Journal of Energy Engineering
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• v.25 no.4
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• pp.103-109
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• 2016

Polyethylene pipes has useful benefits which are anti-corrosive and flexible material, so it is used to gas pipes but also class 3 water pipes of nuclear power plant, process pipes of petrochemical plant and chemical plant. So the usage of polyethylene pipes is widely increased. But it has been limited for the usage of polyethylene, because it can not be directly detected to fusion joints by using non destructive evaluation. Polyethylene pipes are connected by two methods, one is butt fusion and the other is electrofusion. Butt fusion is widely used to connecting the pipes. It is proposed to method for determining the reliability of joints in this study that is detection of the melt flow zone at fusion joints. In this study, middle density polyethylene is used, outside diameter of the test specimen is 225mm and thickness is 20.5mm. Speed of ultrasonic of this test specimen is 2,200m/s. Test specimens were fabricated by varying the heating time which means from 0% to 130% applying time through heating plate to polyethylene for detecting melt flow zone. Also 4 additional test specimens were made, one was made that not scrapping attached surface of pipes but applying 100% of the proper heating time and the others were made to include of soil, gravel and vinly tape paper at fusion joints, that were also applied 100% of proper heating time. Ultrasonic testing to measure the melt flow zone of 20 test specimens was conducted by using 3.5MHz and 5.0MHz ultrasonic probes and melt flow zone measuring was conducted to three times at different point to one specimen. To differentiate the melt flow zone signal, post image processing was equally conducted to all test results and image levels, contrast, sharpen, threshold were adopted to all teat results and the test results were displayed gray scale. From the results, for the shorter heating times the reflection area of multiple echo have been increased, so the data was obtained from the position where it can be eliminated as much as possible. At 80% of proper heating time(168 sec.), the signal of melt flow zone was obtained clearly, so measuring could be conducted. From 7% of proper heating time(15 sec.) to shorter heating times. we could not obtain the signal because test specimen was not fused. From the result, we can verify that measuring of melt flow zone by using phased array ultrasonic imaging method is possible. And we can verify to complete and incomplete butt fusion by measuring the melt flow zone.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.16 no.1
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• pp.1-13
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• 2011

The Yellow Sea Cold Water (YSCW) is formed by cold and dry wind in the previous winter, and is known to spread southward along the central trough of the Yellow Sea in summer. Water characteristics of the YSCW and its movement in the northern East China Sea (ECS) are investigated by analyzing CTD (conductivity-Temperature-Depth) data collected from summertime hydrographic surveys between 2003 and 2009. By water mass analysis, we newly define the North Western Cold Water (NWCW) as a cold water mass observed in the study area. It is characterized by temperature below $13.2^{\circ}C$, salinity of 32.6~33.7 psu, and density (${\sigma}_t$) of 24.7~25.5. The NWCW appears to flow southward at about a speed less than 2 cm/s according to the geostrophic calculation. The newly defined NWCW shows an interannual variation in the range of temperature and occupied area, which is in close relation with the sea surface temperature (SST) over the Yellow Sea and the East China Sea in the previous winter season. The winter SST is determined by winter air temperature, which shows a high correlation with the winter-mean Arctic Oscillation (AO) index. The negative winter-mean AO causes the low winter SST over the Yellow Sea and the East China Sea, resulting in the summertime expansion and lower temperature of the NWCW in the study area. This study shows a dynamic relation among the winter-mean AO index, SST, and NWCW, which helps to predict the movement of NWCW in the northern ECS in summer.

• Journal of the Korean earth science society
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• v.26 no.3
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• pp.240-252
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• 2005

The relationships between wave and wind around the Korean Peninsula have been analyzed with the data from the buoys moored at five stations (Dugjug-do, Chilbal-do, Geomoon -do, Geoje-do, Donghae) by Korea Meteorological Administration. Generally, the relationship between wave and wind is the highest at the stations in the West Sea and the lowest at the stations in the South Sea, and the middle at the station in the East Sea. The characteristics shown at each station are as follows. Highest wave is developed at Chilbal-do with strong northwesterly wind in winter because the sea is opened in the wind direction and wave is amplified by shoaling effect. At Chilbal-do, wave directions coincide with wind directions relatively well. On the other hand, waves are not fully developed at Dugjug-do in winter due to limited fetch since the sea is blocked by Hwanghae-do in the northwest direction. The limitation in fetch is more serious at the stations in the South Sea. In the South Sea, the direction of dominant northerly wind is blocked by land so that wave heights are small even with very strong northerly wind. In the South Sea, whatever wind direction is, waves dominantly come in the direction from the East China Sea, which are from the south at Geomoon-do and the southwest at Geoje-do. At these directions, waves are coming even with weak wind. At the station in the East Sea, waves are highly developed due to vast area, but not so high as in Chilbal-do because wind and wave directions do not coincide in many cases. As shown, wind direction is important in the wave development as well as wind speed. The reason is that the fetch is determined by wind direction. In the case of long-lasted wind with fixed direction at Chilbal-do and Dugjug-do, wave directions are well coincident with wind directions and wave heights increase with response time, which is the duration between the highest wind and wave. However, in the case of disagreement between wind and wave directions at the station in the East Sea, wave heights do not increase as highly as at Chilbal-do and Dugjug-do in spite of strong wind and longer response time. The results show us that waves are highly developed with strong wind, long fetch, and long duration, and also show that wave development ratios are different at different stations due to environmental factors such as the direction towards sea or land, bottom topography, and the scales of adjacent seas.

• The Journal of Korean Academy of Prosthodontics
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• v.46 no.5
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• pp.511-519
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• 2008

Statement of problem: An incompatibility between the initiator systems of self-curing composite resins and light-curing adhesives was supposed recently. Purpose: The purpose of the study was to evaluate the influence of activators for self/dual bonding on dentin shear bonding strengths. Material and methods: Fifty human molars were divided into 5 groups. A flat dentin surface was created for each tooth. A self-curing composite resin (Luxacore) was bonded with the following adhesives (n = 10); One-Step, Prime&Bond NT, AdheSE, Prime&Bond NT and AdheSE were also used in combination with activators. Shear bond strengths were measured after 24 hours of water storage. The specimens were loaded in shear in the Instron until failure at a 1 mm/min crosshead speed. Data were compared using one-way ANOVA and Tukey HSD test (${\alpha}$= 0.05). Results: The dentin adhesive systems in order of decreasing median bond strength were One-Step > Prime&Bond NT with activator, AdheSE with activator > Prime&Bond NT, AdheSE. Among adhesives, One-Step had the highest bond strength. Prime&Bond NT with activator had higher bond strengths than Prime&Bond NT that was used alone, and so was AdheSE. Conclusion: Shear bond strengths were increased in Prime&Bond NT and AdheSE when these were used with activators comparing used without activators. But using activators was not effective clinically comparing One-Step.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.10
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• pp.442-447
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• 2017

The purpose of this study was to establish norm-referenced criteria for the isokinetic strength of the elbow joint in Korean high school baseball players. Two hundred and one high school baseball players participated in this study, none of whom had any medical problem with their upper limbs. The elbow flexion/extension test was conducted four times at a speed of $60^{\circ}/sec$. The HUMAC NORM (CSMI, USA) system was used to obtain the values of the peak torque and peak torque per body weight. The results were presented as norm-referenced criterion valuesusing the 5-point scale of Cajori which consists of five stages (6.06%, 24.17%, 38.30%, 24.17%, and 6.06%). In the results of this study, the peak torques of the elbow (flexor and extensor?) at an angular velocity of $60^{\circ}/sec$ were $37.88{\pm}8.14Nm$ and $44.59{\pm}11.79Nm$, and the peak torque per body weight of the elbow (flexor and extensor?) were $50.06{\pm}8.66Nm$ and $58.28{\pm}12.84Nm$, respectively. The reference values of the peak torque and peak torque per body weight of the elbow flexor and extensor were setat an angular velocity of $60^{\circ}/sec$. On the basis of the results analyzed in this study, the following conclusions were drawn. There is a lack of proper studies on the elbow joint strength, even though the most common injury in baseball players occurs in the elbow joint. Therefore, we need to establish a standard muscle strength in order to prevent elbow joint injuries and improve their performance. The criteria for the peak torque and peak torque per body weight established here in will provide useful information for high school baseball players, baseball coaches, athletic trainers and sports injury rehabilitation specialists in injury recovery and return to rehabilitation, which can beutilized as objective clinical assessment data.