• Geotechnical Engineering
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• v.14 no.5
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• pp.89-110
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• 1998

Variations of backfill load on the metal-polyethylene composite( MPC ) pipes buried in various trenches backfill afterward were investigated in this paper. The backfill loads obtained by the finite element method( FBM ) were compared with those calculated by the well-known MarstonBpangler(M-5) theory. The reliability of the finite element analysis used in this study was examined by an inaitu best for the buried pipe. The backfill lords and deflections on the real-size pipe buried on-site were measured while increasing the backfill height. In addition, further investigations were made for the variations of the backfill loads as a function of several important parameters such as the backfill soil type, bach. height$(\leq4.0m)$, diameter of the pipe$(B.$1.0m)$, and trench width($\leq 3.0 B_c$). It is confirmed that the M-S theory predicts reasonably well the backfill loafs of the MPC of the M-S backfill coils be 0.13 and 0.15 for the SC and SM coils in the D unman soil model, respectively. The load ratio, Wu-s/WwgM for a narrow trench varies negligibly with the back(111 height but fiends to increase for a wide trench. The ratio increases with increasing diameter of the pipe for a narrow trench while decreasing for a wide trench. It is also found that the ratio generally decreases as the degree of compaction increases and BM soil exhibits larger load ratio than that of SC soil.

• International Journal of Highway Engineering
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• v.8 no.3 s.29
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• pp.129-141
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• 2006

The vertical soil pressure developed in the granular layer of asphalt pavement system is influenced by various factors, including the wheel load magnitude, the loading speed, and asphalt pavement temperature. This research observed the distribution of vertical soil pressure in pavement supporting layer by investigating measured data from soil pressure gage in the KHC Test Road. The existing specification of subbase and subgrade compaction was also evaluated with measured vertical pressure. The finite element analysis was conducted to verify the accuracy of results with measured data because it can maximize research capacity without significant field test. The test data was collected from A5, A7, A14, and A15 test sections at August, September, and November 2004 and August 2005. Those test sections and test data were selected because they had best quality. The size of influence area was evaluated and the vertical pressure variation was investigated with respect to load level, load speed, and pavement temperature. The lower speed, higher load level, and higher pavement temperature increased the vertical pressure and reduced the area of influence. The finite element result showed the similar trend of vertical pressure variation in comparison with measured data. The specification of compaction quality for subbase and subgrade is higher than the level of vertical pressure measured with truck load so that it should be lurker investigated.

• FLOWER RESEARCH JOURNAL
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• v.18 no.4
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• pp.238-243
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• 2010

This study was conducted to investigate effects of nutrient solution pH control agent and foliar spray of ethephon on the reduction of stem inside-cavity and improvement of flower quality in chrysanthemum 'Baekma'. Changes of pH in nutrient solution as affected by the kind of pH control agent showed more settled pattern in the plot of KOH treatment than in others. Plant growth and development such as cut flower length, leaf numbers, cut flower weight and petal number were the greatest in the plot of KOH. However, the size and area of stem cavity was large in KOH rather than $KHCO_3$. As changes in the absorbing patterns of mineral elements as affected by nutrient solution pH control agent in closed system, contents of total nitrate, phosphorus, potassium and calcium by $KHCO_3$ was absorbed into the plant less than KOH, so that it remained a lot of mineral element residues rather than KOH in closed system. Plant growth as affected by the foliar spray of ethephon showed growth retardation effect in the plot of solution diluted to 1 : 500 and growth promotion effect in the plot of solution diluted to 1 : 1,000 or 1 : 2,000. The number of petals was the best in the plot of foliar spray of ethephon solution diluted to 1 : 1,000 before flowering at 45 days showing 331 petals compared to control showing 302 petals. The size and area of stem cavity as affected the foliar spray of ethephon was smaller 1 mm and 7%, respectively, in the plot of solution diluted to 1 : 2,000 before flowering at 30 days than in control. Therefore, treating pH stabilization using KOH after floral initiation stage with the foliar spray of ethephon solution diluted to 1 : 2,000 before flowering at 30 days would help to reduce stem cavity size and improve flower quality in hydroponically grown chrysanthemum 'Baekma'.

• Analytical Science and Technology
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• v.31 no.6
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• pp.247-258
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• 2018

The purpose of the present study was to investigate whether the degree of air pollution can be evaluated via examination of local plants. Selected sites included two parks in an industrial area, as well as two parks in an urban area. Selected plant samples comprised one-year-old pine shoot leaves. Leaves growing over 2 m from the ground were collected from over 10 pine trees. Leaf surface was analyzed for deposition of 14 trace elements and 16 polycyclic aromatic hydrocarbons (PAHs), including particle size and mass, surface imaging, precipitation-mediated particle removal rate, and concentration. Particle size ranged from 0.4 to $200{\mu}m$, and the volume percentage of particles ${\leq}10$ was 20 %. Deposited particle mass ranged from 0.450-0.825 mg, and precipitation-mediated removal rate ranged from 10.0-27.6 %. Trace element concentration, as measured by ICP/MS after microwave acid digestion, was 18.8-26.3 mg/kg As, 0.08-0.13 mg/kg Be, 0.06-0.08 mg/kg Cd, 4.91-17.8 mg/kg Cr, 5.26-405 mg/kg Cu, 1,930-2,670 mg/kg Fe, 3.03-28.1 mg/kg Pb, 26.9-42.8 mg/kg Mn, 2.66-10.4 mg/kg Ni, 4,560-8,730 mg/kg Al, 2,500-6,120 mg/kg Ba, 5.27-17.8 mg/kg Rb, 40.9-95.3 mg/kg Sr, and 4,030-8,260 mg/kg Zn. Concentration of PAHs, as analyzed by GC/MS/MS after liquid-liquid extraction and purification of deposited particles, ranged from 1.17 to 12.378 mg/kg for ${\Sigma}PAH_{16}$ and from 1.17 to 12.378 mg/kg for ${\Sigma}PAH_7$.

• Journal of the Korean Geotechnical Society
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• v.38 no.10
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• pp.61-74
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• 2022

Considering that the number of cases in which a structure foundation is located on weathered rock has been increasing recently, for adequate design bearing capacity of a foundation on weathered rock, allowable bearing capacities of such foundations in geotechnical investigation reports were studied. With reference to the study results, the allowable bearing capacity of a foundation on weathered rock was approximately 400-700 kN/m², with a large variation, and was considered a conservative value. Because the allowable bearing capacity of the foundation ground is an important index in determining the foundation type in the early design stage, it can have a significant influence on the construction cost and period according to the initial decision. Thus, in this study, six large-scale plate-bearing tests were conducted on weathered rock, and the bearing capacity and settlement characteristics were analyzed. According to the test results, the bearing capacities from the six tests exceeded 1,500 kN/m², and it shows that the results are similar with the one of bearing capacity formula by Pressuremeter tests when compared with the various bearing capacity formula. In addition, the elastic modulus determined by the inverse calculation of the load-settlement behavior from the large-scale plate-bearing tests was appropriate for applying the elastic modulus of the Pressuremeter tests. With consideration of the large-scale plate-bearing tests in this study and other results of plate-bearing tests on weathered rock in Korea, the allowable bearing capacity of weathered rock is evaluated to be over 1,000 kN/m². However, because the settlement of the foundation increases as the foundation size increases, the allowable bearing capacity should be restrained by the allowable settlement criteria of an upper structure. Therefore, in this study, the anticipated foundation settlements along the foundation size and the thickness of weathered rocks have been evaluated by numerical analysis, and the foundation size and ground conditions, with an allowable bearing capacity of over 1,000 kN/m², have been proposed as a table. These findings are considered useful in determining the foundation type in the early foundation design.

• Environmental Sciences Bulletin of The Korean Environmental Sciences Society
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• v.2 no.2
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• pp.169-179
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• 1998

This paper was performed to estimate interrelations between humus level of sediments and nutrient release from sediments in Dae-cheong reservoir. For investigations, sediments were sampled in June and October, in 1997 at fish farms, embayment, and the main stream of Dae-cheong reservoir. Items for investigation are as follows; water content, weight loss on ignition(IG), porosities of sediments, contents of element such as hydrogen, nitrogen, carbon, and nutrient release rates. Water contents and porosities were measured to conjecture the physical trait and grain size trait. Weight loss on ignition was measured to determine the contents of organic substance. For determination of the humus level of sediments, carbon and nitrogen contents were measured by elemental analyzer. As a result of elemental analysis, C/N ratio was determined in the range of $3.0\~13.1$. From the elemental analysis, humus level of Dae-cheong reservoir sediment was estimated from mesohumic state to oligotrophic state. For the determination of nutrient release rate, $PO_4-P$ and $NH_4-N$ concentrations of interstitial water and overlying water were measured. By using the concentration difference between interstitial water and overlying water and using the Fick's diffusion law, the release rates of phosphorus and nitrogen from the sediment samples were calculated. Release rates of nutrients which directly influence to the water quality were $0.05\~8.63mgP/m^2day$ and $4.99\~36.56mgP/m^2day$. It was found that release rate was measured higher in the 1st sampling period than in the 2nd sampling period. For the determination of phosphorus content in sediment, TPs were measured in 807\~1542{\mu}g/g$ in the 1st samling period and $677\~5238{\mu}g/g$ in the End samling period. Phosphorus release rate and phosphorus content were not interrelated each other.

• Journal of the Korea Concrete Institute
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• v.20 no.1
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• pp.3-11
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• 2008

An experimental investigation was conducted with half-scale representations of the reinforced concrete shear walls with the opening subjected to cyclic loads. Specimens were half scale representations of a one-story wall in the apartment built in 1980. The area ratio of the opening section, as well as the size and critical section of coupling slabs, were decided based on results from a previous researches. The test result of WS-0.23 specimen, which has artificial damages to install the opening, the strength of the wall decreased due to the opening. It is apparent that influence of cutting reinforcing bars and decrease of effective section area lead to early first yield of the reinforcing bars before the allowable limit of drift ratio of the shear walls was reached. Therefore, proper reinforcing method is needed to prevent this. The decrease of strength of the shear walls by installation of openings shows a great deal of difference compared to previous researches. This is because flexural capacity of the slabs is working as coupling elements for the shear walls. The critical section of coupling slabs that works as coupling elements for shear walls was a little different from the results of previous researches.

• Journal of the Korean housing association
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• v.20 no.1
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• pp.59-70
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• 2009

The purpose of the study is to suggest the amount of space for each behavior according to the classification of behavior in the housing to plan the optimal floor space of the elderly housing. The method for calculating space for behavior begins with classifying behaviors, identifying them and then taking pictures of the model of elderly people who reproduce each behavior. Based on the pictures, body parts which are necessary for each behavior are assembled and the formula for behavioral space is created. The space for behavior is produced considering the body dimensions of Korean elderly in their sixty's as well as the furniture size and the psychological distance between people. 3D modeling is used to verify the result. Human behaviors can be classified into individual-related, housework-related, family-related, reception-related and other behaviors. These five behaviors are subdivided into more specific behaviors. The area for each specific behavior is calculated with the anthropometric data of the elderly, preferred furniture dimension and psychological area. As a result the required area for specific behaviors is as follows: the behavior of sleeping in a bed needs $4.3m^2$; the behavior of changing clothes on a chair, $1.7m^2$; the behavior of watching TV on the floor $1.3m^2$, the behavior of working and reading using a desk, $2.1m^2$, the behavior of exercise, $2.5m^2$; the behavior of showering on a chair, $1.3m^2$ and showering using a wheelchair, $1.9m^2$; the behavior of toileting using a wheelchair, $2.3m^2$; the behavior of washing up using a wheelchair, $1.9m^2$; the behavior of eating using a table for four persons, $4.4m^2$; the behavior of cooking and washing dishes, $0.9m^2$ per counter-top; the behavior of washing clothes using a washing machine, $0.9m^2$; the behavior of ironing on the floor $1.4m^2$; the behavior of reception(three persons) on the floor considering personal space, $4.0m^2$; the behavior of taking on and off shoes on a chair, $1.3m^2$. The result of the study is utilized as quantitative data to calculate optimal floor space for elderly housing. In addition, qualitative data such as characteristics of housing preference, spacial usage and storage capacity are necessary to produce the floor space which can provide convenient and safe living environment.

• Journal of the Korea Society of Computer and Information
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• v.17 no.8
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• pp.1-10
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• 2012

This paper proposes design space exploration methodology of many-core processors including multimedia specific instructions to support high-performance and low power ultrasound imaging for portable devices. To explore the impact of multimedia instructions, we compare programs using multimedia instructions and baseline programs with a same many-core processor in terms of execution time, energy efficiency, and area efficiency. Experimental results using a $256{\times}256$ ultrasound image indicate that programs using multimedia instructions achieve 3.16 times of execution time, 8.13 times of energy efficiency, and 3.16 times of area efficiency over the baseline programs, respectively. Likewise, programs using multimedia instructions outperform the baseline programs using a $240{\times}320$ image (2.16 times of execution time, 4.04 times of energy efficiency, 2.16 times of area efficiency) as well as using a $240{\times}400$ image (2.25 times of execution time, 4.34 times of energy efficiency, 2.25 times of area efficiency). In addition, we explore optimal PE architecture of many-core processors including multimedia instructions by varying the number of PEs and memory size.

• Journal of Korean Society of Steel Construction
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• v.25 no.1
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• pp.61-70
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• 2013

A turn-buckle is capable of adjusting the tensile force by left-hand threads and right-hand threads between tension members. There are different types of turn-buckles according to tension member and connection form but the practical and existing turn-buckles are incapable of measuring the tensile force. A turn-buckle for adjusting and measuring tensile force has therefore been developed. This study shows the ultimate strength and reliability for measurement of the new turn-buckles through finite element analysis of the developed ones. From analytic results of the new turn-buckles which have the measurement limit loads of 100kN, 200kN and 300kN, the ultimate strength is approximately five times stronger than the measurement limit capacity. Additionally, a review of the new turn-buckle, which has the measurement limit load of over 300kN, shows that there is a tendency for the size of turn-buckle to become larger. So the connection devices were designed and the loading test was conducted from the concept that the parallel connection of turn-buckle with 300kN capacity can measure the tensile force of 600kN. The results of parallel loading test show the sufficient possibility. Furthermore, the mock-up test was constructed to investigate the release of initial load and corrosion when the new turn-buckle is installed at the outdoor and exposed to rain and atmosphere.