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Challenges to Prevent in Practice for Effective Cost and Time Control of Construction Projects

  • Olawale, Yakubu A.
    • Journal of Construction Engineering and Project Management
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    • 제10권1호
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    • pp.16-32
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    • 2020
  • Cost and time control of projects is important in preventing project failure. However, achieving effective cost and time control in practice is often challenging. The challenges of project cost and time control in practice are investigated by carrying out a questionnaire survey on the top 150 construction contractors in the UK followed by in-depth semi-structured interviews of practitioners from 15 construction companies in the country. Quantitative analysis reveals that design change is the most important factor inhibiting the ability of UK contractors from effectively controlling both the cost and time of construction projects. Four of the top five factors inhibiting effective cost control are also the top factors inhibiting effective time control albeit in a different order. These top factors-design changes, inaccurate evaluation of project time/duration, risk and uncertainty, non-performance of subcontractors and nominated suppliers were also found to be endogenous factors to the project. Additionally, qualitative analysis of the interviews reveals 16 key challenges to prevent for effective project cost and time control in practice. These are classified into four categorised based on where they stem from as follows; from the organisation (1. Lack of integration of cost and time during project control, 2. lack of management buy-in, 3. complicated project control systems and processes, 4. lack of a project control training regime); from the construction management/project management approach (5. Lapses in integration of interfaces, 6. project control not being implemented from the early stages of a project, 7. inefficient utilisation and control of labour, 8. limited time devoted to planning how a project will be controlled at the outset); from the client; (9. Excessive authorisation gates, 10. use of adversarial and non-collaborative forms of contracts, 11. communication problems within client set-up, 12. obstructive client representatives) and; from the project team (13. Lack of detailed/complete design, 14. lack of trust among the project partners, 15. limited time devoted to project control on site, 16. non-factual reporting). The study posits that knowledge of these project control inhibiting factors and challenges is the first step at ensuring they are avoided and enable the implementation of a more effective project cost and time control process in practice.

Seismic risk estimation of the Kirikkale province through street survey based rapid assessment method (SSRA)

  • Sonmezer, Yetis Bulent;Bas, Selcuk;Akbas, Sami Oguzhan
    • Earthquakes and Structures
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    • 제14권6호
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    • pp.615-626
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    • 2018
  • The seismic vulnerability of Turkey is relatively high due to its active fault systems with potential to create destructive earthquakes. Thus, reducing the loss of life and property, the number of the earthquake-prone buildings and their retrofit requirements are considerably significant key issues under the scenario earthquakes. The street survey based rapid assessment (SSRA) method can be considered as a powerful tool to determine the seismic vulnerability of building stock of an earthquake-prone city/state. In this study, the seismic vulnerability of the building stock of the Kirikkale province in Turkey is aimed to be estimated adopting the street survey based rapid assessment method (SSRA). For this purpose, central 2074 existing reinforced concrete (R/C) buildings were structurally surveyed with rapid visual site screening and disadvantages such as, the existence of short-column, soft-story, heavy overhangs, pounding effect and local soil conditions were determined for obtaining the structural performance score of each. The results obtained from the study demonstrate that 11-25% of the surveyed buildings in the study region needs to be investigated through more advanced assessment methods. Besides, higher correlation between increasing story number and unsafe/safe building ratio is obtained for the buildings with soft-story parameter than that for those with heavy overhangs and short-column parameters. The conformity of the results of the current study with the previous documented cases of rapid assessment efforts in the recent earthquakes in Turkey shows that the SSRA method for the Kirikkale province performed well, and thus this methodology can be reliably used for similar settlement areas.

수직형 지중열교환기 열전도도 측정기술에 관한 연구 (A Study on the Measurement of Thermal conductivity of Vertical Borehole heat Exchanger)

  • 김지영;이의준;장기창;강은철
    • 대한설비공학회:학술대회논문집
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    • 대한설비공학회 2008년도 동계학술발표대회 논문집
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    • pp.39-44
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    • 2008
  • The heat exchange between the Borehole Heat Exchanger(BHE) and the surrounding ground depends directly on ground thermal conductivity k at the certain site. The k is thus a key parameter in designing BHE and coupled geothermal heat pump systems. Currently, although a thermal hydraulic response test(TRT) is mostly used in practice, the thermal hydraulic TRT needs additional power and is generally time-consuming. A new, simple wireless P/T probe for a hi-speed k determination was introduced in this paper. This technique using a wireless P/T probe is less time-consuming and requires no external source of energy for measurement and predicts local thermal properties by measuring soil temperatures along the depth. Measured temperature data along the depth was analyzed. In order to verify the new technique for the determination of ground thermal conductivity, ground thermal conductivity k that calculated from the measured temperature data using a wireless P/T probe was compared with one obtained from conventional hydraulic TRT. When comparing the average k of two methods, the relative error was approximately 10%. As a result, the electronic TRT can replace the conventional hydraulic TRT method after carrying out the additional research on a lot of sites.

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An investigation of Panax ginseng Meyer growth promotion and the biocontrol potential of antagonistic bacteria against ginseng black spot

  • Sun, Zhuo;Yang, Limin;Zhang, Lianxue;Han, Mei
    • Journal of Ginseng Research
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    • 제42권3호
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    • pp.304-311
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    • 2018
  • Background: Ginseng black spot disease resulting from Alternaria panax Whuetz is a common soil-borne disease, with an annual incidence rate higher than 20-30%. In this study, the bacterial strains with good antagonistic effect against A. panax are screened. Methods: A total of 285 bacterial strains isolated from ginseng rhizosphere soils were screened using the Kirby-Bauer disk diffusion method and the Oxford cup plate assay. We analyzed the antifungal spectrum of SZ-22 by confronting incubation. To evaluate the efficacy of biocontrol against ginseng black spot and for growth promotion by SZ-22, we performed pot experiments in a plastic greenhouse. Taxonomic position of SZ-22 was identified using morphology, physiological, and biochemical characteristics, 16S ribosomal DNA, and gyrB sequences. Results: SZ-22 (which was identified as Brevundimonas terrae) showed the strongest inhibition rate against A. panax, which showed 83.70% inhibition, and it also provided broad-spectrum antifungal effects. The inhibition efficacies of the SZ-22 bacterial suspension against ginseng black spot reached 82.47% inhibition, which is significantly higher than that of the 25% suspension concentrate azoxystrobin fungicide treatment (p < 0.05). Moreover, the SZ-22 bacterial suspension also caused ginseng plant growth promotion as well as root enhancement. Conclusion: Although the results of the outdoor pot-culture method were influenced by the pathogen inoculum density, the cropping history of the field site, and the weather conditions, B. terrae SZ-22 controlled ginseng black spot and promoted ginseng growth successfully. This study provides resource for the biocontrol of ginseng black spot.

하악 부분 무치악 환자의 골유착성 임플랜트 주위 연조직에 관한 연구 (The study of the peri-inplant soft tissue around osseointegrated implants in partial edentulous patients)

  • 정근식;임성빈;정진형
    • Journal of Periodontal and Implant Science
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    • 제27권3호
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    • pp.561-573
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    • 1997
  • The keratinized mucosa around the implant is an important key in health of soft tissue and hard tissue. The purpose of this study is showed that the keratinized mucosa is associated with the keratinized mucosa index, plaque index, gingival index, probing depth. which is investigated to observing the peri-implant mucosa of mandibular partial edentulous patuent using periodontal parameter by previously published paper. It was estimated 6 site with regard to 80 fixture for 28 person, and the average age is 46.8. Each estimation is the order of less trauma, that is, plaque index, keratinized mucosa index, gingival index and probing depth. In this study, statstically analyzed treatment is used for Spss V 7.0 for Windows(Spss Inc, USA). The Kruskal Walis Test is used to compare the amount of the keratinized mucosa is into the $0{\sim}3$ index, with plaque index, gingival index and probing depth. Mann-whitney Test is used to interpreate the relation of plaque index and probing depth, which is showed significant difference. The Result are as follows 1. The kertinized mucosa index 3 amounts to 47.7%, which is much higher than the other indices and the index order is followed 3, 1, 2 and O. 2. The plaque index 1 amounts to 61.7%, which is much higher than the other indices and the index order is followed 1, 2, 3 and O. The plaque index 0 is significant to each of index(P<0.05). The plaque index is decrease as the keratinized mucosa index is increased. 3. The probing depth for 2mm, 1mm, 3mm is 48.9%, 23.5%, 16.8% respectively, which is most occupied. The probing depth 2mm and 3mm for the keratinized mucosa index is significant(P<0.05). The probing index is decreased as the keratinized mucosa index is increased. 4. The gingival index 0 amounts to 58.0%, which is much higher than the other indices and the index order is followed 0, 1, 2 and 3.

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변위된 미맹출 상악 견치의 교정 치험례 (ORTHODONTIC TREATMENT OF THE DISPLACED UNERUPTED MAXILLARY CANINE : CASE REPORT)

  • 임혜정;최남기;김선미;양규호
    • 대한소아치과학회지
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    • 제32권3호
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    • pp.543-549
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    • 2005
  • 상악 견치는 가장 긴 치근을 가지며 저작기능과 함께 하악의 측방운동을 유도하고 심미적으로도 치열궁의 구각부위에 위치하여 교합관계의 조화와 대칭을 유지하는 등의 중요한 기능을 수행한다. 상악 견치는 발육기간이 가장 길며 형성되어 맹출하기까지 복잡한 경로를 갖기 때문에 다른 치아보다 매복의 빈도가 높다. 이러한 매복치를 치료하기 위해 임상의는 관찰을 하거나 외과적 노출과 교정적 견인, 자가치아이식, 발치 등 다양한 치료방법을 고려할 수 있다. 외과적 노출과 교정치료는 견치를 교합선상에 배치할 수 있기 때문에 가장 이상적인 접근으로 생각할 수 있다. 본 증례 보고는 구개측으로 매복된 상악 견치를 외과적 노출과 교정적 치아이동을 통해 기능적, 심미적으로 양호한 결과를 얻었다.

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고려인삼(Panax ginseng C.A. Meyer) ATPase $\alpha$-subunit 유전자의 Cloning (Molecular Cloning of ATPase $\alpha$-Subunit Gene from Mitochondria of Korean Ginseng (Panu ginseng C.A. Meyer))

  • Park, Ui-Sun;Choi, Kwan-Sam;Kim, Kab-Sig;Kim, Nam-Won;Choi, Kwang-Tae
    • Journal of Ginseng Research
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    • 제19권1호
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    • pp.56-61
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    • 1995
  • Molecular cloning and restriction mapping on ATPase $\alpha$-subunit gene (atpA) were carried out to obtain genomic information concerned with the gene structure and organization in Korean ginseng mitochondria. Two different clones containing the homologous sequence of atpA gene were selected from SalI and PstI libraries of mitochondrial DNA (mtDNA) of Korean ginseng. The sizes of mtDNA fragments inserted in SalI and PstI clones were 3.4 kb and 13 kb, respectively. Southern blot analysis with [$^{32}P$] labelled Oenothera atPA gene probe showed that atpA gene sequence was located in 2.0 kb XkaI fragment in PstI clone and in 1.7 kb XbaI fragment in SalI clone. A partial sequening ascertained that the SalI clone included about 1.2 kb fragment from SalI restriction site to C-terminal sequence of this gene but about 0.3 kb N-terminal sequence of open reading frame was abscent. The PstI fragment was enough large to cover the full sequence of atpA gene. The same restriction pattern of the overlapped region suggests that both clones include the same fragment of atiA locus. Data of Southern blot analysis and partial nucleotide sequencing suggested that mtDNA of Korean ginseng has a single copy of atpA gene. Key words ATPase a-subunit, mitochondrial DNA, Panax ginseng.

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장스팬형 경량복합리브 PSC슬래브 구조공법에 관한 비교분석 및 실험적 연구 (Experimental Study and Comparison of Analysis Results on Structural Method of Prestressed Concrete Slab Using Light Hybrid rib to Long Span)

  • 심남주;오중근
    • 한국건설관리학회논문집
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    • 제18권5호
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    • pp.3-10
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    • 2017
  • HBS 슬래브는 PSC슬래브 상부에 경량체를 설치하고 이웃하고 있는 PSC슬래브의 두 개 리브가 현장 토핑 콘크리트에 의해 형성된 현장 리브와 결합함으로서 동일축상에서 단일 부재로 거동하는 공법이다. 본 연구의 목적은 PSC 슬래브 공법에 관하여 실험적 연구를 통하여 기존 공법과의 성능 비교를 구현 하는 것이다. 본 연구에서는 기존 공법의 한계를 개선하는 공법으로 HBS 슬래브를 개발하였으며 그 우수성을 검증하기 위하여 기존 공법과의 성능 비교를 시행하고자 한다. 기존 공법과의 구조 성능 비교는 HBS 슬래브의 실험적 연구를 통하여 휨성능 및 전단에 대한 구조 성능과 PC보와 HBS 슬래브의 접합 성능을 검토하였으며, 이론적 방법을 통하여 기존 공법과 비교를 수행하고자 한다.

시각적 웹 인터페이스에 대한 기호학 의미 (The Significance of Semiotics for Visual Web Interface)

  • 장승영
    • 한국전자통신학회논문지
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    • 제13권4호
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    • pp.795-802
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    • 2018
  • 본 논문은 정보를 내재하고 있는 집약적 웹 인터페이스에 대한 기호학 은유의 광범위한 사용과 인터페이스 디자인에 대한 메타포의 은유가치에 관한 논고를 통해서 기호학 이론적 해석을 서술하게 되었다. 웹 설계에 있어 영향을 미치는 공통요소는 웹 기호를 생성하기 위한 경험적 확립과 검증적 제공에 있으며 사이트의 유용성과 주요요소를 평가하는 데 사용하는 중요한 요소적 관점을 지닌다. 또한 웹 기술적 기능을 적용하면서 부터 화면의 구조가 동적으로 변모하기 시작하였으며 매체 기능들이 웹 표준을 만드는데 중요한 차원으로 시각적 구조화를 기호학적 측면에서 구현하게 되었다. 무엇보다 기호를 탐구하는 기술적 표현방식으로 취급하기 보다는 자연스럽고 보편적인 다양한 분야에서의 기호학 접근방식이 적용함으로써 기호적인 측면에서 휴먼 - 컴퓨터 인터페이스를 통해 미적코드를 마련하게 되었고 이를 바탕으로 의도된 의미를 사용자에게 전달하기 위해 의사소통의 수단으로 활용하며 사용자 인터페이스의 유용성 문제와 메타포의 중요성을 강조할 수 있게 되었다.

한부모가족의 복지 지원체계로서의 가상공동체 활용에 관한 기초 연구 - 웹사이트 활용을 중심으로 - (A Study on Practical Use of Cyber Community as Welfare Support System for Single-Parent Family - Focused on Practical Using Websites-)

  • 강기정;이무영;김영희
    • 대한가정학회지
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    • 제40권10호
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    • pp.141-159
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    • 2002
  • The purpose of this study is to find plan of practical using websites as welfare support system for present single-parent family practically. The subject websites were chosen by search in twice using Yahoo(http://www.yahoo.co.kr),Naver(http://www.naver.com).Empas(http://www.empas.com). The first search was accomplished by reference to these websites from the eighth of December to the twelfth of December in 2001. With the use of key words‘widowed mother & widower’,‘divorce’,‘single parent’,‘single-parent home’,‘single-parent family’. The second search was conducted on March 27, 2001. Finally 10 websites were selected. Chosen websites were analysed by structural element measure and structural technique measure of the contents. The following are summary of results and conclusion of this study. First, counsel program, self-help group, legal advice of the legal system and legal question area in the field of psychology·emotion·health problem of subject websites satisfied desire of single-parent family comparatively. Second, subject websites were classified into two types which are after the assessment of contents and structural technique of subject websites, a imaginary site was designed to solve the problem of single-parent family and to support single-parent family by means of prior research. Putting the result mentioned above together, As a step to solve the problem of single-parent family, to use practically website as a place single-parent family can be provided what the country and community cannot offer. It was accomplished by expanding self-help group extremely through the connection with ground to acquire strategy of dealing with single-parent family's desire and problem, volunteer supports and specialists.