• Computers and Concrete
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• 제21권4호
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• pp.407-417
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• 2018

Concrete which is a composite material is one of the most important construction materials. Compressive strength is a commonly used parameter for the assessment of concrete quality. Accurate prediction of concrete compressive strength is an important issue. In this study, we utilized an experimental procedure for the assessment of concrete quality. Firstly, the concrete mix was prepared according to C 20 type concrete, and slump of fresh concrete was about 20 cm. After the placement of fresh concrete to formworks, compaction was achieved using a vibrating screed. After 28 day period, a total of 100 core samples having 75 mm diameter were extracted. On the core samples pulse velocity determination tests and compressive strength tests were performed. Besides, Windsor probe penetration tests and Schmidt hammer tests were also performed. After setting up the data set, twelve artificial intelligence (AI) models compared for predicting the concrete compressive strength. These models can be divided into three categories (i) Functions (i.e., Linear Regression, Simple Linear Regression, Multilayer Perceptron, Support Vector Regression), (ii) Lazy-Learning Algorithms (i.e., IBk Linear NN Search, KStar, Locally Weighted Learning) (iii) Tree-Based Learning Algorithms (i.e., Decision Stump, Model Trees Regression, Random Forest, Random Tree, Reduced Error Pruning Tree). Four evaluation processes, four validation implements (i.e., 10-fold cross validation, 5-fold cross validation, 10% split sample validation & 20% split sample validation) are used to examine the performance of predictive models. This study shows that machine learning regression techniques are promising tools for predicting compressive strength of concrete.

• 한국환경생태학회지
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• 제20권2호
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• pp.227-234
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• 2006

히어리의 자연집단과 벌채집단간의 비교는 전라남도 순천시 승주읍 접치재, 월등면, 황전면, 경상남도 진주시 명석면, 경기도 포천시 백운산 5곳의 벌채지와 주변 자연림에 분포하는 히어리군락을 대상으로 비교하였다. $100m^2$당 맹아수와 개체당 평균 맹아수는 벌채 집단에서 자연집단의 것보다 더 높게 나타났다. 반면 맹아수별 수고와 직경은 자연집단에서 더 높게 나타났다. 종조성과 식생상관성은 없으며 벌채집단과 자연집단 모두에서 큰차이 없이 생육하였다. 개괄지인 벌채집단에서 근맹아 뿐만 아니라 실생묘로도 번식하였다. 이처럼 히어리는 환경적응력이 커서 인간이 훼손시킨 벌채집단에서 근맹아와 실생묘로 번식함으로써 종 자체의 소멸은 없고, 오히려 일시적인 교란이후에 개체군 확장을 보였다.

• Archives of Reconstructive Microsurgery
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• 제6권1호
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• pp.29-38
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• 1997

A peripheral nerve when approximation of the ends imparts tension at the anastomosis and with a relatively long segment defect after excision of neuroma and neurofibroma cannnot be repaired by early primary suture. The one of the optimistic reconstruction method of severed peripheral nerves is to restore tension-free continuity at the repair site putting an autogenous nerve graft into the neural gap despite of ancipating motor or sensory deficit of the donor nerve area. To overcome the deficit of the autogenous nerve graft, several other conduits supplying a metabolically active environment which is able to support axon regeneration and progression, providing protection against scar invasion, and guiding the regrowing axons to the distal stump of the nerve have been studied. An author have used ipsilateral femoral vein, ipsilateral femoral vein filled with fresh thigh muscle, and autogenous sciatic nerve for the sciatic nerve defect of around 10 mm in length to observe the regeneration pattern in rat by light and electron microscopy. The results were as follows. 1. Light microscopically regeneration pattern of nerve fibers in the autogenous graft group was more abundant than vein graft and vein filled with muscle group. 2. On ultrastructural findings, the proxial end of the graft in various groups showed similar regenerating features of the axons, myelin sheaths, and Schwann cells. The fascicular arrangement of the myelinated and unmyelinated fibers was same regardless of the type of conduits. There were more or less increasing tendency in the number and the diameter of myelinated fibers correlated with the regeneration time. 3. In the middle of the graft, myelinated nerve fibers of vein filled with muscle group were more in number and myelin sheath was thinner than in the venous graft, but the number of regenerating axons in autogenous nerve graft was superior to that in both groups of the graft. The amount of collagen fibrils and amorphous materials in the endoneurial space was increased to elapsed time. 4. There was no difference in regenerating patterns of the nerve fibers of distal end of the graft. The size and shape of the myelinated nerve fbers were more different than that of proximal and middle portion of the graft. From the above results, the degree of myelination and regenerating activity in autogenous nerve is more effective and active in other types of the graft and there were no morphological differences in either ends of the graft regardless of regeneration time.

• 한국환경생태학회지
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• 제25권5호
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• pp.710-716
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• 2011

본 연구에서는 중국 북경 옌칭(延慶)으로부터 북한 상원지역에 도입한 1년생 묘목 4배체 아까시나무를 대상으로 식재 입지별로 1년생 묘목의 생장특성을 분석하고, 엽내 3가지 성분의 함량 측정을 통해 향후 식재 후 수확한 엽의 사료첨가제로 이용 가능성을 검토하였다. 그 결과, (1) 상원지역에서 평지에 식재한 4배체 아까시나무는 중국의 옌칭지역 내 4배체 아까시나무에 비해 당년생 맹아지의 길이와 근원경이 50%정도 작게 나타났다. (2) 상원지역의 4개 사면입지에서 4배체 아까시나무의 당년생 맹아지의 길이 생장은 동, 서, 남사면에서 북사면에 비해 23~30% 크게 나타났고, 근원경은 동, 남사면의 4배 아까시나무가 북, 서사면에 비해 14~23% 크게 나타났다. (3) 상원지역에서 4배체 아까시나무의 엽내 조단백질과 조회분 함량은 중국 옌칭지역 내 4배체 아까시나무와 마찬가지로 일반 아까시나무 잎에 비해 40% 이상 높게 나타났다.

• Tuberculosis and Respiratory Diseases
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• 제44권3호
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• pp.505-515
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• 1997

배 경 : 폐암환자에서 기관지 침습에 관하여 CT의 정확도를 알아보고, 수술을 시행한 폐암환자에서 CT의 역할을 알아보기 위하여 본 연구를 시행하였다. 대상 및 방법 : 저자들은 폐절제술을 시행한 95명과 엽절제술을 시행한 61명의 수술전 CT를 분석하였다. 엽절제술을 시행 환자중 7명에서는 절제한 기관지 말단에서 암세포가 발견되어 폐절제술을 시행했다. 또한 저자들은 충분한 생검을 한 수술못한 60명의 수술전 CT도 분석하였다. 3mm 이상의 기관지벽의 비후, 불규칙한 기관지벽의 비후 그리고 기관지 직경의 감소를 기관지 침습으로 정하였다. 절제한 기관지 말단의 암세포 발견(20명), 수술한 기관지 말단에서의 폐암재발(6명) 그리고 기관지 생검상 양성(수술 안한군에서 34명)을 기관지 침습으로 생각하였다. 결 과 : 기관지 침습에 관하여 CT는 예민도 (11.5%), 낮은 양성기대치 (38%), 그러나 높은 특이도 (96%), 그리고 비교적 높은 정확도 (84%)를 나타냈으며, 수술 안한 군에서는 높은 예민도(62%), 양성 기대치를 보였다. 결 론 : 시행한 폐암환자에서 CT는 폐암의 기관지 침습에 대하여 예민도와 양성 기대치가 낮았다. 이와 같은 결과로 기관지 침습에 대한 CT의 유용성은 제한적이라 생각되며, 수술전 기관지경에 의한 기관지벽 생검이 필요하리라 생각된다.

• 한국농공학회지
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• 제17권3호
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• pp.3860-3871
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• 1975

This experiment was carried out to establish the mechanized methods in stumping and root-clearing, which were the most important works in the reclamation of sloping uplands. The determination of optimum teeth interval of rake blades and its operation methods to reduce the quantity of transported topsoil during the works, are the aims of this investigation. A newly designed rake blade, whose net teeth intervals could be regulated by three stages as 15cm, 25cm, and 35cm, was manufactured to attach to the bulldozer of 13ton. The experiments were carried out at Kilsang-Myon, Kwangwha-Gun, from Aug. 9 to Aug. 23, 1975. For each interval, 36 test plots of 50${\times}$10mn in size, which were regulated under three levels of land slopes of 10, 20, and 30% and two different tree stand density of high or medium values, were randomly chosen and arranged by two-replicated split-split plot design. Each stump classified by its diameter was stumped and cleared by the rake dozer to be related between diameter and stumping time. The results obtained in this experiment can be summarized as follows: 1. Stumping times for the diameters ranging from 6 to 18cm of stumps are almost the same and they are not varied by the difference of teeth intervals of rake dozer. 2. By back-ward stumping method, the number of stumps which can be stumped per hour ranges almost from 100 to 170, showing significant difference with respect to the teeth intervals. The working area is sharply varied with not only the stand density of stumps but the teeth intervals. 3. Optimum stumping distance for each teeth interval of rake dozer to minimize the quantity of transported topsoil are varied with such the rates as it is 15m or 20m for 15cm of teeth interval, but 25m for 25cm or 35cm, respectively. The clearing distance could be chosen almost double as long as the operating distance. 4. The working areas per hour of the simultaneous stumping and clearing methods are no significant difference among the various treatments of working conditions, but they are affected by the operating techniques. However, the influencing factors of the working conditions as classified before and the working directions are ranged from 10 to 15 per cent of total working area, respectively. 5. The residual rates of stumps which are not stumped by the rake dozer in each test plot are generally reduced as the teeth interval gets narrower, but there are no significant difference among them. The mean residual rates average to be about 4% for the simultaneous stumping and clearing method. The back-ward stumping method are recommended to be supervised and directed by more than one man, to show the operator where the stumps are located. 6. The results according to the stumping and clearing methods are summarized as Table IV-2. And the selection of working methods is recommended to follow as shown in Fig. IV-9 with respect to the stand density of the field. 7. Generally speaking, the narrower the teeth interval, the better become the working results, but the more the quantity of transported topsoil is increased. Therefore, it is recommended that the teeth interval should be reduced from the present distance of more than 30cm to 25cm or 15cm, by developing suitable working methods through more field works and experiments.

• Current Research on Agriculture and Life Sciences
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• 제9권
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• pp.147-155
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• 1991

노지재배(露地栽培)한 Lilium elegans 'Connecticut king'의 구근(球根) 굴취시기(掘取時期)를 개화기(開花期)인 6월 5일부터 7월 25일까지 10일(日) 간격(間隔)으로 나누고 잔존엽수(殘存葉數)를 달리해서 일정기간(一定期間) 냉장처리(冷藏處理)($3{\pm}1^{\circ}C$, 0~105일간(日間) 8처리(處理))한 후(後) 촉성재배(促成栽培)한 결과(結果)는 다음과 같다. 1. 맹아율(萌芽率)은 저온처리기간(低溫處理期間)이 길어질수록, 잔존엽수(殘存葉數)가 많을수록 그리고 구근비대기간(球根肥大期間)이 길수록 증가(增加)하는 경향(傾向)이었으며 개화기(開花期)의 미숙구근(未熟球根)도 짧은 저온처리(低溫處理)로 높은 맹아율(萌芽率)을 나타내었다. 개화율(開花率)을 보면 개화기(開花期)의 미숙구근(未熟球根)과 엽(葉) 10매(枚)를 남기고 50일간(日間) 비대(肥大)시킨 구근(球根) 그리고 엽(葉)20매(枚)를 남기고 30일이상(日以上) 비대(肥大)시킨 구근(球根)을 90일간(日間) 저온처리(低溫處理)하였을때, 또 전엽(全葉)을 남기고 30일이상(日以上) 비대(肥大)시킨 구근(球根)을 60일간(日間) 저온처리(低溫處理)했을때 90%이상(以上)의 높은 개화율(開花率)을 나타내었다. 2. 맹아(萌芽) 및 개화(開花)소요일수(日數)는 저온처리일수(低溫處理日數)가 증가(增加)함에 따라 짧아지는 경향(傾向)이었으며 특히 개화(開花)소요일수(日數)에 있에서는 개화기(開花期)의 미숙구근(未熟球根)이 타(他) 처리구(處理區)에 비해 가장 짧았고 정식(定植) 후(後) 100 일 이내에 개화(開花)시킬 수 있었다. 3. 초장(草長), 착화수(着花數), 경경(莖經)등은 공히 개화후(開花後) 구근비대기간(球根肥大期間)이 길수록 증가(增加)하였으며 개화기의 미숙구근(未熟球根)이 가장 저조한 생육(生育)을 나타내었다. 그러나 대구(大球)를 사용(使用)한다면 구근비대기간(球根肥大期間)없이 개화기(開花期)의 미숙구근(未熟球根)을 사용(使用)하여 연내(年內) 절화재배(切花栽培)가 가능할 것으로 판단(判斷)되었다.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• 제31권3호
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• pp.199-218
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• 2005

Purpose of Study: Peripheral nerve regeneration depends on neurotrophism of distal nerve stump, recovery potential of neuron, supporting cell like Schwann cell and neurotrophic factors such as BDNF. Peripheral nerve regeneration can be enhanced by the conduit which connects the both sides of transected nerve. The conduit maintains the effects of neurotrophism and BDNF produced by Schwann cells which can be made by gene therapy. In this study, we tried to enhance the peripheral nerve regeneration by using calcium phosphate coated porous conduit and BDNF-Adenovirus infected Schwann cells in sciatic nerve of rats. Materials and Methods: Microporous filter which permits the tissue fluid essential for nerve regeneration and does not permit infiltration of fibroblasts, was made into 2mm diameter and 17mm length conduit. Then it was coated with calcium phosphate to improve the Schwann cell adhesion and survival. The coated filter was evaluated by SEM examination and MTT assay. For effective allogenic Schwann cell culture, dorsal root ganglia of 1-day old rat were extracted and treated with enzyme and antimitotic Ara-C. Human BDNF cDNA was obtained from cDNA library and amplified using PCR. BDNF gene was inserted into adenovirus shuttle vector pAACCMVpARS in which E1 was deleted. We infected the BDNF-Ad into 293 human mammary kidney cell-line and obtained the virus plaque 2 days later. RT-PCR was performed to evaluate the secretion of BDNF in infected Schwann cells. To determine the most optimal m.o.i of BDNF-Ad, we infected the Schwann cells with LacZ adenovirus in 1, 20, 50, 75, 100, 250 m.o.i for 2 hours and stained with ${\beta}$-galactosidase. Rats(n=24) weighing around 300g were used. Total 14mm sciatic nerve defect was made and connected with calcium phosphate coated conduits. Schwann cells$(1{\times}10^6)$ or BDNF-Ad infected Schwann cells$(1{\times}10^6)$ were injected in conduit and only media(MEM) was injected in control group. Twelve weeks after surgery, degree of nerve regeneration was evaluated with gait analysis, electrophysiologic measurements and histomorphometric analysis. Results: 1. Microporous Millipore filter was effective conduit which permitted the adhesion of Schwann cells and inhibited the adhesion of fibroblast. We could enhance the Schwann cell adhesion and survival by coating Millipore filter with calcium phosphate. 2. Schwann cell culture technique using repeated treatment of Ara-C and GDNF was established. The mean number of Schwann cells obtained 1 and 2 weeks after the culture were $1.54{\pm}4.0{\times}10^6$ and $9.66{\pm}9.6{\times}10^6$. 3. The mRNA of BDNF in BDNF-Ad infected Schwann cells was detected using RT-PCR. In Schwann cell $0.69\;{\mu}g/{\mu}l$ of DNA was detected and in BDNF-Adenovirus transfected Schwann cell $0.795\;{\mu}g/{\mu}l$ of DNA was detected. The most effective infection concentration was determined by LacZ Adenovirus and 75 m.o.i was found the most optimal. Conclusion: BDNF-Ad transfected Schwann cells successfully regenerated the 14mm nerve gap which was connected with calcium phosphate coated Millipore filter. The BDNF-Ad group showed better results compared with Schwann cells only group and control group in aspect to sciatic function index, electrophysiologic measurements and histomorphometric analysis.