• Journal of the Architectural Institute of Korea Planning & Design
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• v.34 no.11
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• pp.113-123
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• 2018

First of all, the multi-story Housing applying resident's participation in europe was classified by the menu selection method, the two-step supply method and the cooperative method. And then I analyzed flexible unit plan of cases for deriving the planning methode and the characteristics of flexibility. First, I analyzed the area and form of the unit plan, structure and Installation, fixed and variable elements to derive the planning method. The area of units are distributed from a minimum of $35m^2$ to a maximum of $150m^2$, and many of the unit planes have a narrow front and a deep depth. The structure is a long-span wall-structure or a skeleton structure, and is designed without any columns and bearing walls in the interior space for flexibility in spatial composition. The vertical shafts are located in the center of the unit in a box-form or in the corner at the unit dividing wall for free placement of interior wall. Fixed elements are framework and facility systems. Most of the future residents in the two-steps supply method and the cooperative method were able to freely design the internal space within the zoning concept proposed by the architect and change the location of the facade element within module system proposed by the architect. Second, the characteristics of the flexibility applied to the unit plan were divided in integrated flexibility, functional flexibility, construction flexibility, and supply flexibility. The integrated flexibility enables residents to give the variable space combination based on the complex structure of the inner space for providing various living experiences. Regarding functional flexibility, the three-dimensional spatial structure with neutral space has multi-functionality according to the needs of residents and easily accepts mixing of hybrid programs such as work and residence. Constructive flexibility allows residents to create identity by freely planning interior space and changing the size or location of facade components in a determined system of architects. Finally, various types of size and space composition are proposed and realized in the whole building applying menu selection method, so that flexibility in the offer can accommodate and integrate various types of living.

• Journal of the Korea institute for structural maintenance and inspection
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• v.24 no.5
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• pp.111-118
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• 2020

The U-shaped composite beam used in this study consist of a reinforced concrete structure, a beam steel structure supporting the slab, a reinforced concrete structure, and a U-shaped steel plate. The U-shaped composite beam was developed for the purpose of using it as a parking lot because it is highly constructible and has low floor height and long span. For the improvement of constructivity, the U-shaped composite beam ends are planned with standardized H-shaped steel and connected directly to the columns, and the middle of the U-shaped composite beam consists of U-shaped steel plates folded in U-shaped form using thin steel plates (t=6) instead of H-shaped steel. In the middle of the composite beam, where U-shaped steel plates are located, the depth of U-shaped beam may be planned to be small so as to satisfy the height limit of the parking lot. It is important to grasp the structural performance according to the change of depth because low beam depth is advantageous for the reduction of the floor height, but it is a inhibitor to the structural behaviors of U-shaped composite beam. In addition, since U-shaped composite beams are a mixture of steel frame structures, reinforced concrete structures and U-shaped steel plates, securing unity has a great influence on securing structural performance. Therefore, in this study, a structural experiment was conducted to understand the structural performance according to the depth change for U-shaped composite beam. A total of three specimens were planned, including two specimens that changed the depth using a criteria specimen planned for a general parking lot. The results of the experiment showed that the specimens who planned the depth greatly had better structural performance such as yield strength, maximum strength, and energy than the standard specimen.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.43 no.5
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• pp.543-553
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• 2023

This study was conducted to propose a simple method to evaluate the load-carrying capacity of RC slab bridges, which have been most frequently constructed in Korea. A number of RC slab bridges have been considerably deteriorated associate with the long service year. However, since these bridges are not included in the 1st and 2nd class infrastructures due to their short span length, they have been relatively neglected compared to other bridge types in terms of safety management. In the previous theoretical study, a process (draft) was proposed for evaluating the damage of RC slab bridges using the relationship between the displacement response ratio and the stiffness reduction rate derived by the measured displacement and natural frequency. In this paper, to verify the validity of the proposed damage evaluation process (draft), the results to the actual bridges were compared with the safety grade and the Matsui's deterioration index. In addition, to enhance the practical applicability of the existing process (draft), an improved method approximately evaluating the load-carrying capacity using only the measured natural frequency was presented. If an error of 10% of the load-carrying capacity is allowed, it is judged that the proposed damage evaluation process can be appropriately used not only for evaluating the safety of RC slab bridges, but also for determining priorities for their maintenance.

• Proceedings of the Korea Information Processing Society Conference
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• 2011.04a
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• pp.576-579
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• 2011

Wireless sensor network are widely all over different fields. Because of its distinguished characteristics, we must take account of the factor of energy consumed when designing routing protocol. Wireless sensor networks consist of small battery powered devices with limited energy resources. Once deployed, the small sensor nodes are usually inaccessible to the user, and thus replacement of the energy source is not feasible. Hence, energy efficiency is a key design issue that needs to be enhanced in order to improve the life span of the network. In BCDCP, all sensors sends data from the CH (Cluster Head) and then to the BS (Base Station). BCDCP works well in a smallscale network however is not preferred in a large scale network since it uses much energy for long distance wireless communication. TBRP can be used for large scale network, but it weakness lies on the fact that the nodedry out of energy easily since it uses multi-hops transmission data to the Base Station. Here, we proposed a routing protocol. A Cluster Based Energy Efficient Tree Routing Protocol (CETRP) in Wireless Sensor Networks (WSNs) to prolong network life time through the balanced energy consumption. CETRP selects Cluster Head of cluster tree shape and uses maximum two hops data transmission to the Cluster Head in every level. We show CETRP outperforms BCDCP and TBRP with several experiments.

• Journal of the Korean Geotechnical Society
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• v.24 no.7
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• pp.61-73
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• 2008

Piles of a bridge pier are connected with the column through the pile cap (footing). Behavior of the pile foundation can be different according to the connection method between piles and the pile cap. Connection methods between pile heads and the pile cap are divided into two groups : rigid connections and hinge connections. Domestic design code has been specified to use rigid connection method for the highway bridge. In the rigid connection method, maximum bending moment of a pile occurs at the pile head and this helps the pile to prevent the excessive displacement. Rigid methods are also good to improve the seismic performance. However, some specifications prescribe that conservative results through investigations of both the fixed-head condition and the free-head condition should be reflected in the design. This statement may induce an over-estimated design for the bridge which has high-quality structures with casing covered drilled shafts and the PC-house contained pile cap. Because the assumption of free-head conditions (hinge connections) is unreal for the elevated pile cap system with multiple piles of the long span sea-crossing bridges. On the other hand, elastic displacement method to evaluate the pile reactions under the pile cap is not suitable for this type of bridges due to impractical assumptions. So, full modeling techniques which analyze the superstructure and the substructure simultaneously should be performed. Loads and stress state of the large diameter drilled shaft and the pile cap for Incheon Bridge which will be the longest bridge of Korea were investigated through the full modeling for rigid connection conditions.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.28 no.4A
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• pp.537-548
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• 2008

Recently, the prestressed unbonded concrete structures are increasingly being built. The mechanical behavior of prestressed concrete beams with unbonded tendon is different from that of normal bonded PSC beams in that the increment of tendon stress was derived by whole member behavior. The purpose of the present paper is therefore to evaluate the flexural behavior and to propose the equation of ultimate tendon stress by performing static flexural test according to span/depth, concrete compression strength, reinforcement ratio and the effect of existing bonded tendon. From experimental results, for cracking, yielding and ultimate load, the effect of reinforcement ratio was more effective than concrete compression strength, and the beams having high strength concrete had a good performance than having low concrete, but there was no difference between high strength and low strength. And as L/dp was larger, test beams had a long region of ductility. This means that unbonded tendon has a large contribution after reinforcement yielding. Especially, the equation of ACI-318 was not match with test results and had no correlations. After analysis of test results, the equation of ultimate unbonded tendon stress without slip was proposed, and the proposed equation was well matched with test results. So the proposed equation in this paper will be a effective basis for the evaluation of unbonded tendons without slip, analysis and design.

• Korean journal of applied entomology
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• v.47 no.4
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• pp.337-343
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• 2008

This study was conducted to investigate the distribution pattern, ecological characteristics and life cycle of the Black Soldier Fly (Hermetia illucens, BSF). The BSF was widely distributed throughout Korea. The insect was mainly found in the vicinity of and in cattle sheds, manure sheds, living waste dump grounds, and food waste dump grounds. Developmental characteristics of the BSF are as follows: the egg was long oval shaped of 887 ${\mu}m$ in the major axis and 190 ${\mu}m$ in the minor axis; it weighed 24 ${\mu}g$. Female oviposited ca. 1,000 eggs on average; eggs hatched in 81 hours under laboratory condition ($27^{\circ}C$, 60% R.H.). The duration of the larval stage was approximately $15{\sim}20$ days. The size of the last instar larvae was 21 mm. The cuticle of the pupae gradually acquired red-brown color and the size of them was 19 mm. The pupal stage was shorter for females (16 days) than males (15 days). Adults were sized about $13{\sim}20$ mm long and black-colored. The life span of adult insects was $5{\sim}8$ days for the first generation (June${\sim}$July), $7{\sim}10$ days for the second generation (Aug.${\sim}$Sept.), and $13{\sim}18$ days for the third generation (Sept.${\sim}$Oct.). Mating started on the next day of emergence and actively occurred at the third day after emergence. Mating mostly occurred between 10:00 and 16:00 during which light intensity is highest. Egg-laying started on the third day and was most frequent from the fourth to the sixth day after emergence. Similar to mating time, females oviposited mostly between 10:00 and 16:00.

• Journal of Hospice and Palliative Care
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• v.13 no.1
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• pp.24-31
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• 2010

Purpose: A central venous catheterization (CVC) is frequently used for delivering anti-cancer chemotherapeutic agents, blood products, parenteral nutrition, and other intravenous therapy in patients with cancer. Major complications of CVC use are thrombosis, infection, and mechanical complications. The aim of this study was to evaluate the frequency of CVC complications and related factors. Methods: The records of cancer patients who received a CVC at our university hospital from March 2001 to October 2006 were retrospectively investigated. Chi square test was used to determine whether there was a related factor for thrombosis or infection, and Kaplan-Meier analysis for univariate analysis, or Cox-regression analysis for multivariate analysis was used for catheter life span. Results: Three hundred and ten CVCs (235 nontunneled, 75 tunneled) were inserted in 310 patients (157 males, 153 females). Among them, 104 had hematologic cancers and 206 had solid cancers. The mean age of the patients was 52 years (range, 19~82 years). CVC complications occurred in 60 cases (19%). CVC-related thrombosis occurred frequently in patients with infection (P=0.003), whereas diagnosis, catheter type, transfusion, and TPN history did not affect infection or thrombosis. The mean duration of the catheter was 102 days (range, 2~1,330 days), and the duration was prolonged in patients with tunneled catheters (P=0.000), or without transfusion through CVC (P=0.030). Conclusion: The major complications for long-term use of a CVC were infectionand thrombosis. Tunneled catheter was effective tool for long term use, especially in cases without transfusion through CVC. The studies on the prevention or treatment ofthrombosis and infection are, therefore, warranted by using CVC for an extended period of time.

• The Korean Journal of Financial Management
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• v.25 no.1
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• pp.51-84
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• 2008

We investigate the signaling effect of repurchase preceding new equity issue using Korean data. In a short time span, firms announce stock repurchases and equity offerings. The proximity of two events in Korean firms indicates that those are not independent of each other. In this paper, we test the signaling effect of repurchase on equity offerings on the two measures. One is announcement effect, which is measured as CAR(0, +2). The other is the effectiveness which is measured as CAR(0, +30) because the price movement during this window influences on the price of new issues. Previous studies that stock repurchase convey positive signal to equity offerings-Billet and Xue(2004) and Jung(2004)-construct sample without the limit of time interval between two events. This causes the unclear relation between those because of the long time interval. In this study we consider only samples of being within one year each other to reduce this problem and clarify the signal of repurchase on equity offerings. Korean firms are allowed to repurchase own shares with two different method. One is direct repurchase as same as open market repurchase. The other is stock stabilization fund and stock trust fund which trust company or bank buy and sell their shares on the behalf of firms. Generally, the striking different characteristic between direct repurchase and indirect repurchase is following. Direct repurchase is applied by more strict regulation than indirect repurchase. Therefore, the direct repurchase is more informative signal to the equity offering than the indirect repurchase. We construct two sample firms- firms with direct repurchase preceding-equity offerings and indirect repurchase-preceding equity offering, and one control firms-equity offerings only firms-to investigate the announcement effect and the effectiveness of repurchases. Our findings are as follows. Direct repurchase favorably affect the price of new issues favorably. CAR(0, +2) of firms with direct repurchase is not different from that of equity offerings only firms but CAR(0, +30) is higher than that of equity offerings only firms. For firms with indirect repurchase and equity offerings, Both the announcement effect and the effectiveness does not exist. Jung(2004) suggest the possibilities of how indirect stock repurchase can be regarded as one of unfair trading practices on based on the survey results that financial managers of some of KSE listed firms have been asked of their opinion on the likelihood of the stock repurchase being used in unfair trading. This is not objective empirical evidence but opinion of financial managers. To investigate whether firms announce false signal before equity offerings to boost the price of new issues, we calculate the long-run performance following equity offerings. If firms have announced repurchase to boost the price of new issues intentionally, they would undergo the severe underperformance. The empirical results do not show the severer underperformance of both sample firms than equity offerings only firms. The suggestion of false signaling of repurchase preceding equity offerings is not supported by our evidence.

• Parasites, Hosts and Diseases
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• v.23 no.1
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• pp.7-17
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• 1985

In order to determine the susceptible age of Enterobius vermicular is to anthelmintics and to observe the chronologie growth of female E. vermicularis in man, experimental infections were done. About 500 eggs were challenged to 19 volunteers. After 4, 8, 16, 20, 24, 28, 32 and 35 days of infection, each case was treated by either mebendazole or pyrantel pamoate. On the 40th day of infection all cases including control were treated again to terminate the experimental infection and to evaluate the effect of previous treatment. Each case collected 3-day stools to harvest the expelled worms. The results could be summarized as follows: 1. The infection rates of females were in range of 0.6~13.1 % in control cases. Because the collected worms showed comparable growth and development by day, the worms were concluded to be derived from experimental infection. 2. Cases that were treated with mebendazole on 4, 8 and 16 days after infection expelled 37.5%, 2.5% and 67.5% of the number expelled by a control case on the 40th day. Cases treated thereafter expelled no worms on the 40th day. 3. Cases that were treated with pyrantcl pamoates on 4, 8, 16, 24, 28, 32 and 35 days, expelled 90.7%, 25%, 45.3%, 8%, 2.7%, 5% and 29.3% of the number collected from control cases in respect. 4. All the worms collected were females. The total body length increased consistently and comparably from the 20th day of infection. Those collected on the 20th day were 2.5~3.0 mm long with vagina, sac-like structure and strands of ovaries; 24 day-old worms may have short uterus, 28 day-old worms had long uterus without eggs, 32 day-old worms began to produce eggs, 35 day-old worms showed wide variations in egg deposit in uterus, and 40 day-old worms had uterus filled with eggs from vulva to anal levels. From the above results, it was inferred that the life span of female Enterobius vermicularis was longer than 40 days, and the developmental stages of worms younger than 16 days resisted considerably to both mebendazole and pyrantel pamoate.