• Korean Journal of Construction Engineering and Management
• /
• v.19 no.3
• /
• pp.89-96
• /
• 2018

This study derived big issues in overseas construction through big data analysis. To derive big issues in overseas construction, candidate groups of big issues were identified through big data analysis targeting 53,759 issues including 39,436 issues from major portal sites, 10,387 issues from daily newspapers, and 336 issues in construction magazines from Oct. 1, 2016 to Sep. 30, 2017. The main results are as follows: First, the main issues of overseas construction for the past one year showed that markets were concentrated in Middle East Asia and most of them were low-price order plant projects, which revealed the limitations. Although orders of overseas construction were slightly upward in the first half of 2017 compared to previous year, overseas construction orders are still unstable due to uncertainties in the international affairs and drops in oil prices. Second, the interest topics based on the 8th core keywords of overseas construction among the overseas construction issues for the past one year showed that region (29.9%), corporation environment (22.0%), profitability (17.0%), organizations (15.1%), projects (5.2%), market environment (3.6%), policy and system (3.6%), and education (3.5%) in the order of interest. Third, 10 core issues that have expandability and persistence of discourse were extracted out of 30 issue candidates with regard to eight keywords. Based on the extracted issues, detailed analysis on each of the core issues in overseas construction and correlation analysis between 10 core issues were conducted.

• Journal of Bio-Environment Control
• /
• v.18 no.1
• /
• pp.51-59
• /
• 2009

Bulb onion cultivation area has been restricted in southern part of Korea to avoid blotting and bulb division. The traditional culture method is transplanting bare-rooted plantlet into the field at the end of summer and harvesting at the beginning of next summer. The hot weather and weak plantlets occasionally causes unstable supply of onions in autumn. In order to enlarge cultivation area and to reduce culture period, long nursery system using plug tray and spring transplanting was tried. Forty cultivars collected from Korea and Japan were nursed using 200-plug tray and transplanted to the field in spring. Marketable yield was not related to the seedling size but lodging time. Cultivar of 'Hamasodachi' was lodged early and resulted low marketable yield. Cultivar of 'Cheonjudaego' was not lodged and yielded high but not in accordance with storability. Generally early lodged cultivars showed low storability. In order to avoid rainy harvesting season, cultivars requires excessive long time for lodging is not recommended for spring culture. Using plug nursery and spring transplanting, we successfully produced marketable onions in 3 months. But immediate using of the harvested onion is recommended. The storability of produced onions showed different result among cultivars, storage of spring onion was not recommended.

• Journal of Environmental Science International
• /
• v.2 no.2
• /
• pp.153-160
• /
• 1993

The problem of supply and transport of sediment from a mountainous catchment is very important in explaining dynamic geomorphology and the hydrological cycle. The discharge of suspended sediment is determined by a morphological system. Human interference to environment Is also an important, not negligible factor in sediment production. Moreover, growing concern in recent years for the problems of nonpoint pollution and for the transport of contaminants through terrestrial and aquatic ecosystems has highlighted the role of sediment-associated transport in fluvial systems. This study was conducted in forested and quarried catchments in order to clarify the different discharge process and the mechanism of suspended sediment dynamics for each catchment. As a forested catchment, the Yamaguchi River catchment which drains a $3.12km^2$ area was chosen. On the other hand, the Futagami River basin which is formed by three subbasins (1.07, 1.59 and $1.78km^2$), as a quarried catchment was selected. These catchments are situated to the north and east of Mt. Tsukuba, Ibaraki, Japan. The discharge pattern of suspended sediment from the Futagami River basin is more unstable and irregular than that from forested catchment, the Yamaguchi River catchment. Under the similar rainstorm conditions, suspended sediment concentration from quarried catchment during a rainstorm event increases from 43 to 27,340 mg/l. However, in the case of the forested catchment it changes only from nearly zero to 274 mg/l. Generally, the supply source of suspended sediment is classified into two areas, the in-channel and non-channel source areas. As a result of field measurements, in the case of the forested catchment the in-channel (channel bed, channel bank and channel margin) is the main source area of suspended sediment. On the other hand, remarkable sediment source area on the Quarried catchment is the non-channel that is unvegetated ground.

• Journal of the Korean association of regional geographers
• /
• v.3 no.1
• /
• pp.1-12
• /
• 1997

The climatic characteristics of Korea are analized with the data observed from 1972 to 1995 in 66 stations, using the climatic year method expressed by the $K{\ddot{o}}ppen's$ system of climatic classification. The climate of Korea is composed of the six climatic year types : Cfa, Cwa, Cwb, Dfa, Dwa and Dwb type. The Cwa and Dwa type occupy 95% occurrence frequency. The Cwa climatic year type predominates in the greater part of the Southern Area, the east slopes of the Taebaek Range and Cheju-do, the Dwa type does in Yongso Area and the northeastern part of Kyonggi Province. and the Cfa type does in Ullung-do. Such dominant climatic year regions become the stable climatic regions, while the regions where the various climatic types appear become the unstable climatic regions which are distributed in the northern part of the Southern Area and in the southern part of the Central Area owing to the shifts of the border between C type and D type. The border between C and D type is located in the Central Inland Area in the first half of the 1990's which the Cwa type predominates most. On the other hand the border is located in the middle part of the Southern Area in the first half of the 1980's which the Dwa type prevails most. Therefore the extents of the climatic year regions vary each year. In the interannual change of the main climatic year types, the Cwa type shows the increasing trend, while the Cfa and Dwa type reflets the decreasing tendency. The extending trend of the Cwa climatic year region appears during the period of the first half of the 1970's and the period between the latter half of the 1980's and the first half of the 1990's centering around the Southern Area. The Dwa climatic year region which was predominant in the Central Area in the first half of the 1980's has been reduced up till the recent years.

• Journal of the Korean association of regional geographers
• /
• v.15 no.1
• /
• pp.1-15
• /
• 2009

This study aims to provide preliminary data needed for establishing policies on the environment and disasters of Goryeong county. The main results are as follows. First, the present master plan of the region does not reflect local socio-economic and environmental conditions and the local people's opinion. Second, The air conditions of Gyeongbuk province and Goryeong county are within the permitted limit of air pollution of Korea. Third, the analysis of water pollution index in Nakdong river system shows improvement of water quality in both Andong and Goryeong. Fourth, the conditions of waste collection and disposal are improved in both Gyeongbuk province and Goryeong county. Fifth, in case of environmental pollutant emitting facilities of Gyeongbuk province, the proportion of 1st to 4th grade(relatively much more environmental pollutant emitting quantity than 5th grade) tends to be increasing. Sixth, environmental pollutant emitting facilities of Goryeong county are remarkably increasing in Dasan, Gaegin, Ssangrim, involving industrial complex. Finally, in case of disasters, it is relatively stable in Yecheon, Gumi, Uiseong, Yeongju and Cheongdo, while relatively unstable in Seongju, Gunwi, Yeongcheon, Chilgok, Mungyeong, Bonghwa and Goryeong.

• Journal of Korean Society of Coastal and Ocean Engineers
• /
• v.12 no.2
• /
• pp.70-80
• /
• 2000

Princeton Ocean Model (POM) is modified to construct a three-dimensional, semi-implicit hydro¬dynamic model with a wetting-and-drying scheme. The model employs semi-implicit treatment of the barotropic pressure gradient terms and the vertical mixing terms in the momentum equations, and the velocity divergence term in the vertically-integrated continuity equation. Such treatment removes the external mode and thus the mode splitting scheme in POM, allowing the semi-implicit model to use a larger time step. Applied to hypothetical systems, both the semi-implicit model and POM give nearly the same results. The semi-implicit model, however, runs approximately 4.4 times faster than POM showing its improved computational efficiency. Applied to a hypothetical system with intertidal flats, POM employing the mode splitting scheme produces noises at the intertidal flats, that propagate into the main channel resulting in unstable current velocities. Despite its larger time step, the semi-implicit model gives stable current velocities both at the intertidal flats and main channel. The semi-implicit model when applied to Kyeonggi Bay gives a good reproduction of the observed tides and tidal currents throughout the modeling domain, demonstrating its prototype applicability.

• Analytical Science and Technology
• /
• v.15 no.6
• /
• pp.502-508
• /
• 2002

See-through hollow cathode glow discharge cell has been developed for the trace analysis of metal ions. The systems consists of new glow discharge cell improved the cooling system. In the case of previous type of hollow cathode glow discharge cell, it had been utilized for the trace analysis of metal ions but it had a problem that the plasma becomes unstable by air-cooled device. In this study, the modified hollow cathode glow discharge cell has been developed in order to minimize the problem associated with the air-cooled device. thus the stability of the plasma with water-cooling device has been improved and also the higher plasma temperature has been measured. The fundamental characteristics of modified systems have been investigated. And the discharge parameters, such as discharge pressure, material, and diameter of cathode, have been studied to find optimum discharge conditions.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.12 no.7
• /
• pp.3341-3352
• /
• 2011

In this study, characteristics of wastewater treatment of sewage intermittently mixed with industrial wastewater is examined by investigating the operational status of each unit operation and measuring water quality. The bioreactor operating condition was measured for MLSS concentration 2,000~3,000 mg/L, HRT 5.3~16.3 hour, SRT 2.8~66.6 day, and SVI frequently showed the value above 200 which was higher than the optimal range of 50~150. It is thought that the sludge is not in suitable condition for sedimentation caused by the incoming industrial wastewater. When industrial wastewater is come into the system, MLDO inside of bioreactor rapidly increased, rate of nitrification is steeply decreased, and Pin floc. is spilled in the secondary clarifier. In the observance of microorganism showed that various bacterial floc. and ciliata were found as well as actinomycetes and filamentous bacteria(Sphaeotilus) which is known to cause bulking. Efficiency of each unit operation was fairly good in average. However, efficiency of the bioreactor treatment showed high fluctuation by unstable operating condition by intermittently incoming industrial wastewater.

• The Journal of Engineering Research
• /
• v.5 no.1
• /
• pp.73-87
• /
• 2004

The synthesis and crystallization of amorphous calcium carbonate($CaCO_3$.$nH_2 O$) obtained from gas-liquid reaction between aqueous solution of calcium hydroxide and carbon dioxide at 15~$50^{\circ}C$ are investigated by electrical conductometry, XRD and TEM. The results are as follows: The initial reaction products prior to the formation of precipitated calcium carbonate is amorphous calcium carbonate. The electrical conductivity values in the slurry are decreased during the formation of amorphous calcium carbonate which covers particle surface of calcium hydroxide and retard the dissolution of calcium hydroxide into the solution. that amorphous calcium carbonate is unstable in the aqueous solution and crystallizes finally to calcite by the through-solution reaction. While amorphous calcium carbonate crystallizes into chain-like calcite, the conductivity values are recovered rapidly and the apparent viscosity of slurry containing higher concentration of calcium hydroxide increase. At below pH 9.5, chain-like calcite separates into individual particles to form precipitated calcium carbonate. The formation and synthetic temperature range of amorphous calcium carbonate is most suitable a primary decreasing step(a-step) at $15^{\circ}C$ in the electrical conductometry.

• Journal of Chest Surgery
• /
• v.44 no.1
• /
• pp.9-17
• /
• 2011

Background: A peripheral extracorporeal membrane oxygenator (p-ECMO) has been developed to support patients who are dying due to a serious cardiopulmonary condition. This analysis was planned to define the clinical situation in which the patient benefits most from a p-ECMO. Material and Methods: Between June 2007 and Aug 2009, a total of 41 adult patients used the p-ECMO. There were 23 males and 18 females (mean age $54.4{\pm}15.1$ years). All patients had very unstable vital signs with hypoxia and complex cardiac problems. We divided the patients into 4 groups. In the first group, a p-ECMO was used as a bridge to cardiac operation. In the second group, patients did not have the opportunity to undergo any cardiac procedures; nevertheless, they were treated with a p-ECMO. In the third group, patients mostly had difficulty in weaning from CPB (cardiopulmonary bypass) after cardiac operation. The fourth group suffered from many complications, such as pneumonia, bleeding, infections, and LV dysfunction with underlying cardiac problems. All cannulations were performed by the Seldinger technique or cutting down the femoral vessel. A long venous cannula of $DLP^{(R)}$ (Medtronic Inc, Minneapolis, MN) or $RMI^{(R)}$ (Edwards Lifesciences LLC, Irvine, CA) was used together with a 17~21 Fr arterial cannula and a 21 Fr venous cannula. As a bypass pump, a Capiox emergency bypass system ($EBS^{(R)}$; Terumo, Tokyo, Japan) was used. We attempted to maintain a flow rate of $2.4{\sim}3.0\;L/min/m^2$ and an activated clotting time (ACT) of around 180 seconds. Results: Nine patients survived by the use of the p-ECMO. Ten patients were weaned from a p-ECMO but they did not survive, and the remainder had no chance to be weaned from the p-ECMO. The best clinical situation to apply the p-ECMO was to use it as a bridge to cardiac operation and for weaning from CPB after cardiac operation. Conclusion: Various clinical results were derived by p-ECMO according to the clinical situation. For the best results, early adoption of the p-ECMO for anatomical correction appears important.