• Economic and Environmental Geology
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• v.44 no.3
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• pp.239-246
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• 2011

Groundwater in small islands is used as main water resource but the overuse of groundwater may cause seawater intrusion and temperature decrease in geothermal wells. This study aimed to characterize the hydrogeology of Maeum-ri area in Seokmo Island of Ganghwagun using long-term monitoring at groundwater wells and geothermal wells. In the monitoring period seasonal water level change, consistent drop or increase of water levels are not detected. The groundwater temperature about 10m below ground surface shows year cycle variation having two to five months difference with ambient temperature cycle. The storativity was calculated by tidal method. The storativity estimated by adapting tidal efficiency factor showed some larger values than that by using tidal time lag. The result suggested that the tidal method assuming several assumptions on aquifer condition may produce broad ranges but the calculated ranges at this application are reasonable. The similar shape of groundwater level change and tidal effects was observed at several wells clustered east-south-east direction which may implicate the distribution of vertical fracture system strongly related with groundwater flow channels. The applied methodology and study results will bc valuable to evaluate optimal pumping rate for the preservation of groundwater resources, and to manage geothermal development.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.48 no.1
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• pp.35-42
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• 2020

Electromechanical Actuator(EMA) for flight vehicles generally serves to control the fin deflection angle or the thrust vector angle. This paper deals with design and development of EMA for both aerodynamic control and thrust vector control. In this paper, a novel compact EMA is proposed that can simultaneously control both the tail fin and the jet vane with one actuator and detach the jet vane after vertical launch and rapid turn of the flight vehicle so as to increase efficiency during flying to target. To do this, we designed the EMA using a push-push link mechanism and derived a mathematical model. The mathematical model is validated by comparing simulation result and experimental data. The performance and reliability of the proposed EMA have been verified through performance test, environmental test and ground test. The proposed EMA is expected to be useful as an EMA for flight vehicles because of its simple and compact structure, as well as its performance and reliability.

• Restorative Dentistry and Endodontics
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• v.20 no.2
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• pp.627-643
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• 1995

The resistance to fracture of the restored tooth may be influenced by many factors, among these are the cavity dimension and the physical properties of the restorative material. The placement of direct composite resin restorations has generally been found to have a strengthening effect on the prepared teeth. It is the purpose of this investigation to study the relationship between the cavity isthmus and the fracture resistance of a tooth in composite resin restorations. In this study, MO cavity was prepared on the maxillary left first molar and then filled with composite resin. Three dimentional model with 3049 nodes and 2450 8-node blick elements was made by the serial photographic method and isthmus (1/4, 1/3, 1/2 and 2/3 of intercusplal distance between mesiobuccal cusp tip and mesiolingual cusp tip) was varied. Two types of model(B and R model) were developed. B model was assumed perfect bonding between the restoration and cavity wall and R model was left unfilled. A load of 1500N was applied vertically on the node from the lingual slope of the mesiobuccal cusp. The results were as follows : 1. There was a significant decrease of stress resulting in increase of fracture resistance in B model when compared with R model. 2. When it comes to stress distribution, the stress was concentrated in the facio-gingival line angle and the buccal side of the distal margin of the cavity in both Band R model. 3. With the increase of the isthmus width, the stress decreased in the area of the facio-gingival line angle, and increased in the area of facio-gingival line angle as well as the buccal side of the distal margin of the cavity in B model. In R model, the stress increased both in the area of facio-gingival line angle and the buccal side of the distal margin of the cavity, therefore the possibility of crack increased. 4. As the width of cavity increased, in B model, the direction of crack moved from horizontal to vertical on the facio-gingival line angle and the facio-pulpal line angle. In R model, the direction of the crack was horizontal on the facio-gingival line angle and moved from horizontal to the $45^{\circ}$ direction on the facio-pulpal line angle.

• Journal of the Korean Institute of Landscape Architecture
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• v.34 no.1 s.114
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• pp.92-106
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• 2006

The process of designing Cheonggyecheon Entrance Plaza began with researching four keywords: plaza, restoration. modernity and icon. The outcome of the research was reinterpreted into and informed the design. An urban plaza must not only be a stage for civic life but should also be a portrait of the city to which it belongs. Many Korean plazas, however, are treated as if they are parks. Yeouido Park, which was originally a vast urban void, and Seoul Plaza, recently paved with grass, are good example. The strong 'green myth' can hinder socio-political activities. Cheonggyecheon cannot be said to have been 'restored', since it is still disconnected from its origin and upper streams, and the water is circulated by electricity. So it is better understood as an artificial urban waterfront, rather than an ecologically restored stream. This fact might diminish its ecological value, but not its recreational one. The entrance plaza therefore should reflect that the new stream brings back an 'experience', not only water itself. At the same time, the catch phrase of this restoration project was 'post-modern'. The demolished Cheonggye Expressway represents the 'economy drive' of the 1970s, so the newly opened Cheonggyecheon serves as a perfect counterpart to it. But modernity in Korea is the spirit that made many of the good things, not only its shortcomings, we have now. And from the philosophy of this restoration project, we can see that it is still an ongoing attitude in a way. Remnant of Cheonggye Expressway can evoke our nostalgia for the era. There are plenty of symbols in Seoul, both as architecture and objects. But none of them provide citizens with experience, other than the experience of looking at them. Cheonggyecheon Entrance Plaza is a good place to serve as an icon for a dynamic Seoul. From the research, the designer concluded that this plaza should commemorate the incomparable horizontal experience of Cheonggyecheon and the old expressway, amid the vertical metropolis. The Pedestrian Sculpture, which people can stroll on and look out over Cheonggyecheon, is to be made of steel cladding with a core structure and represents the dynamism of the stream, Seoul and contemporary Korea. The choice of material and the steel structure are also ways of creating the icon. The Water Plaza, the space underneath the ramp, will accommodate people and their urban activities, providing an opportunity to play with water. The Waterblades will be a device for the dramatic beginning of the stream, simultaneously camouflaging ugly openings in the outlets. The Wall of Archaeology is to be made with pre-fab resin blocks, translucent enough so that people can see through any archaeological findings of the site. The strong water-resistant character of resin makes the wall steady throughout the flood season as well. Cheonggyecheon restoration project is an effort to combine contemporary urban demand with the once-existing physicality by evoking our nostalgia for it. The project itself shows many socio-political issues of present-day Korea. The entrance plaza design thus is focused on suggesting an icon for the metropolis, simultaneously celebrating the stream itself. Within this space, people will be exposed to a unique experience that any 'green myth' cannot offer.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.2
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• pp.1339-1347
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• 2015

This study discusses a remote control torch system equipped with a GMAW double wire reel. The welding machine is 30m away from the wire feeder at the industrial site and the feeder is three to five meters away from the torch. Accordingly, the welders cannot control the current and voltage that meets the welding condition during work when they are working at a place that prevents them from seeing the control panel, such as inside a vehicle or tank or at a far work site. They also have no choice but to stop working to change the wire reel when it is burned out completely. Such work suspension resulting from frequent moves to adjust the current and voltage as well as to replace the wire and subsequent cooling causes welding defects. This study produced a remote control torch equipped with a double wire reel by simplifying and streamlining the existing GMAW functions to reduce the troubling issue. The remote control torch equipped with a double wire reel and the existing $CO_2$ /MAG welding torch were applied as a V-groove butt in the vertical position using 6mm rolled steel for a SM50A welding structure. After welding, the condition of welded surface beads underwent a visual inspection and radiographic inspection to analyze the welding quality inside the welded part. This study also evaluated the reduction of welding defects, cost saving, the replacing performance against the existing commercial welders, and the effects on possible compatibility.

• International Journal of Highway Engineering
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• v.12 no.4
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• pp.101-110
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• 2010

In this paper, it has been studied about the CRCO to maintain or rehabilitate the aged JCP. The CRCO and JCO was constructed at useless section of Seo-Hae-Ahn express highway in South Korea. The performance evaluation was conducted. Especially, it was focused on the roll of longitudinal reinforced steels inserted into the CRCO. On crack survey results from field construction section, the reflection cracks at joint of the existing pavement occurred in CRCO. However, due to the constraints of longitudinal reinforced steels, crack width was small. Total crack length and quantity in the CRCO more than that in the JCO. And crack spacing in the CRCO was narrower than it in the CRCP. Through the bonding strength test results, if the cold milling and cleaning as well as surface treatment is applied, there will be no debonding problem at interlayer in the early age. From analysis of the horizontal behavior at the joint, the longitudinal reinforced steels constrained crack width which became wider than initial state over time. Also, that steel in the CRCO reduced the horizontal movement due to temperature variation(4 times than that in the JCO). But, if interface is debonded, the roll decreased. Vertical VWG data showed that CRCO did not occur debonding problem at steel location, but there was some problem in JCO. It was confirmed by field coring. The tensile strain appeared in the CRCO, But the compressive strain occurred in the JCO in early age. Through the FWD test result, deflection in the CRCO was less than that in the JCO. And K value in the CRCO was greater than it in the JCO.

• Korean Journal of Remote Sensing
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• v.33 no.3
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• pp.301-311
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• 2017

Aerosol optical properties as well as vertical location of layer can alter the radiative balance of the Earth by reflecting and absorbing solar radiation. In this study, radiative transfer model (RTM) and satellite-based analysis have been used to quantify the top-of-atmosphere (TOA) radiative effect of aerosol layers in the cloudy atmosphere of the northeast Asia. RTM simulation results show that the atmospheric warming effect of aerosols increases with their height in the presence of underlying cloud layer. This relationship is higher for stronger absorbing aerosols and higher surface albedo condition. Over study region ($20-50^{\circ}N$, $110-140^{\circ}E$) and aerosol event cases, it is possible to qualitatively identify absorbing aerosol effects in the presence of clouds by combining the UV Absorbing Aerosol Index (AAI) derived from Total Ozone Mapping Spectrometer (TOMS), cloud parameters derived from the Moderate Resolution Imaging Spectro-radiometer (MODIS), with TOA Upward Shortwave Flux (USF) from the Clouds and the Earth's Radiant Energy System (CERES). As the regional-mean radiative effect of aerosols, 6 - 26 % lower the USF between aerosols and cloud cover is taken into account. These results demonstrate the importance of estimation for the accurate quantification of aerosol's direct and indirect effect.

• Archives of Plastic Surgery
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• v.38 no.4
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• pp.383-390
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• 2011

Purpose: To correct the upper lip depression after the correction of unilateral cleft lip, autologous grafts such as bone, dermal, fascial grafts and fat injections or alloplastic implants are used. Transplanted bones, dermis and fascia have a tendency to be absorbed and have donor morbidity. Fat injections are absorbed inconsistently and alloplastic implants have problems such as foreign body reactions, protrusions and infections. Authors corrected the upper lip depression using conchal cartilage graft in unilateral cleft lip deformity and the results was analysed with photos. Methods: 26-unilateral cleft lip and 2-microform cleft lip cases, totally 28 cases were performed. Their mean age was 21.89 years. The male and female cases were 12 and 16, respectively. Under anesthesia (general: 18 cases and local: 10 cases), cavum conchae (n=8), cymba conchae (n=16) and whole conchae (n=4) were harvested. Transversely cut the margin of the obtained cartilage, we cut out the most bent portion and put a partial-thickness incision on concave surface in cases of excessive convexity. Then, we performed the onlay graft of the conchal cartilage via scar revision site in unilateral cleft lip and via the reconstruction site of the cupid bow in microform cleft lip. The augmentation of the upper lip was evaluated with photos. Adapting the baseline connecting between the both cheilions as a horizontal standard line, we measured the highest point among the tangents between the upper lip and nose (point a), the lowest point (point c), the middle point between a and c (point b) and the vertical line from the alare (point d) to the horizontal standard line. To assess the postoperative symmetry, we compared cleft side upper lip contour index (%) A,B,C,D=(a,b,c,d)-ch ${\times}$ 100/(ch-ch) and non-cleft side upper lip contour index (%) A',B',C',D'= (a',b',c',d')-ch ${\times}$ 100 / (ch-ch).h) Results: After the surgery, no complication was found except in one case which double layers graft performed in the cleft lip deformity, the lateral portion was protruded. The upper lip contour index, the difference of A and A' were-0.83%, and thus the mild depression was persisted. Difference of B and B', C and C', D and D' were 0.83%, 1.07%, 0.90%. There were statistically significant difference, and thus the depression of upper lip were improved generally. Conclusion: Authors performed the onlay graft of the conchal cartilage in unilateral cleft lip deformity and found that the depression of the upper lip was well corrected except the uppermost part when photogrammetrically analyzed.

• Land and Housing Review
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• v.2 no.4
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• pp.397-406
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• 2011

This research aims to develop various infill-systems for practically applying to long-life housing with 100-year durability and flexibility as a strategy for realizing sustainable residential environment. Especially, the developed infill-systems & technologies were concentrated to the mock-up house applied with the standard model of long-life housing, and their in-situ applicability by a phase, experts' consultation, and questionnaire survey were also evaluated. This research was executed to divide by 3 phases. In the First phase infill-systems for a housing unit of $84m^2$ exclusive use area as well as a support of whole structure and infill-systems including dry wall, and windows were constructed, and their in-situ applicability were evaluated. In the Second phase vertical integration of upper and lower housing units of $50m^2$ and $40m^2$ exclusive use area was investigated the first in domestic for 3 housing units of $50m^2$ exclusive use area. In addition, various infill-systems including the horizontal expansion of $50m^2$ and $10m^2$ exclusive use areas were also constructed and evaluated on their in-situ applicability. In the third phase diverse performance tests and field investigation for in-situ verifying of dry Ondol, developed this research, were executed to improve their practicability. Inner dry walls were taken apart, moved and re-constructed for verifying their practicability to investigate 3R-Reduce, Reuse and Recycle-realization too.

• Journal of Korea Water Resources Association
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• v.51 no.7
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• pp.543-554
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• 2018

A methodology has been presented for evaluating the partial safety factors on the sliding failure mode of vertical caissons of composite breakwaters and for determining the cross sections of those by Level I reliability-based design method. Especially, a mathematical model has been suggested for the sake of a consistency of code format as well as convenience of application in practical design, for which the uncertainties associated with buoyancy and its own weight can be taken into account straightforwardly. Furthermore, design criteria equation has been derived by considering accurately the effect of uplift pressure, so that the cross sections of caissons can be assessed which must be safe against the sliding failure. It has been found that cross sections estimated from partial safety factors proposed in this paper are in very good agreement with the results of Level II AFDA and Level III MCS under the same target probability of failure. However, partial safety factors of the Technical Standards and Commentaries for Port and Harbour Facilities in Japan and Coastal Engineering Manual in USA tend to estimate much bigger or smaller cross sections in comparison to the present results. Finally, many reliability re-analyses have been performed in order to conform whether the stability level of cross section estimated by Level I reliability-based design method is satisfied with the target probability of failure of partial safety factors or not.