• Journal of the Korea Academia-Industrial cooperation Society
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• v.12 no.1
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• pp.233-247
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• 2011

With recent increase in growth without employment and unemployment rate, Business Incubator (BI), which is the birthplace of business start-up, is drawing much attention. Therefore, numerous studies had been carried out from the perspectives of efficient operation and performances of BI. Preceding studies at home and abroad were concentrated mainly on the effect of Critical Success Factors of BI on performance, or on internal operational programs or support services of BI. Recently, assertion that potential capacity of companies located in BI at the time of their commencement of occupancy imparts effect on the performance has been presented. Therefore, this Study, in order to pursue research on above issues, will, firstly, analyze the effect of the characteristics of evaluation of companies wishing to be located in BI conducted by each BI, and, secondly, regulation effect of characteristics of evaluation of companies wishing to be located in BI imparted on performance in connection with the work capabilities of BI and capabilities of manager. The results of analysis illustrated that the expertise, among the capabilities of CEO, imparts affirmative effect on the success rate of business start-up. Product competitiveness and marketability displayed affirmative effect on the success rate of business start-up when work capability (operational intensity) is applied. In particular, although the financing capability of CEO of the company located in BI, as an important factor, imparts negative effect on the success rate of business start-up, it implies affirmative regulation effect through the capabilities of manager.

• Safety and Health at Work
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• v.10 no.4
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• pp.452-460
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• 2019

Background: Monitoring and control of PM_2.5 are being recognized as key to address health issues attributed to PM_2.5. Availability of low-cost PM_2.5 sensors made it possible to introduce a number of portable PM_2.5 monitors based on light scattering to the consumer market at an affordable price. Accuracy of light scatteringe-based PM_2.5 monitors significantly depends on the method of calibration. Static calibration curve is used as the most popular calibration method for low-cost PM_2.5 sensors particularly because of ease of application. Drawback in this approach is, however, the lack of accuracy. Methods: This study discussed the calibration of a low-cost PM_2.5-monitoring device (PMD) to improve the accuracy and reliability for practical use. The proposed method is based on construction of the PM_2.5 sensor network using Message Queuing Telemetry Transport (MQTT) protocol and web query of reference measurement data available at government-authorized PM monitoring station (GAMS) in the republic of Korea. Four machine learning (ML) algorithms such as support vector machine, k-nearest neighbors, random forest, and extreme gradient boosting were used as regression models to calibrate the PMD measurements of PM_2.5. Performance of each ML algorithm was evaluated using stratified K-fold cross-validation, and a linear regression model was used as a reference. Results: Based on the performance of ML algorithms used, regression of the output of the PMD to PM_2.5 concentrations data available from the GAMS through web query was effective. The extreme gradient boosting algorithm showed the best performance with a mean coefficient of determination (R²) of 0.78 and standard error of 5.0 ㎍/㎥, corresponding to 8% increase in R² and 12% decrease in root mean square error in comparison with the linear regression model. Minimum 100 hours of calibration period was found required to calibrate the PMD to its full capacity. Calibration method proposed poses a limitation on the location of the PMD being in the vicinity of the GAMS. As the number of the PMD participating in the sensor network increases, however, calibrated PMDs can be used as reference devices to nearby PMDs that require calibration, forming a calibration chain through MQTT protocol. Conclusions: Calibration of a low-cost PMD, which is based on construction of PM_2.5 sensor network using MQTT protocol and web query of reference measurement data available at a GAMS, significantly improves the accuracy and reliability of a PMD, thereby making practical use of the low-cost PMD possible.

• Clinical and Experimental Reproductive Medicine
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• v.1 no.1
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• pp.1-14
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• 1974

Data from this study support the View that the following factors are not sufficiently important in Korea to invalidate the relationships observed between age of marriage and fertility: (1) Premarital pregnancy and common law marriage, (2) shortening of birth intervals in late marriages, (3) adverse effects of very eary marriage in reproductive capacity, and (4) postponement of first pregnancy among early marriages. Thirteen variables which were considered to be potential predictors of fertility were studied to determine their influence on three indices of fertility. Age of marriage and family planning praetice are the strongest predictors and account for about 10% and 7% of the total variance, respectively. Seven other factors each account for an intermediate amount of variability; these are ideal number of children, rural versus urban study area, education, aspiration for daughter, index of exposure to mass media, economic index of respondent's home at survey, and residence before marriage. The remaining variables have no consistently significant relationship to fertility. Most of the relationships appear to be stable and consistent over time; others appear to be changing. The latter group include those variables which are associated with modernization indices of family planning practice, mass media exposure. and aspiration for daughters. Thus, the index of family planning practice is of limited significance for the $40{\sim}49$ age group but is the most important variable for the $20{\sim}29$ year women. The relationship is a direct one for the two age groups between 30 and 49 years which suggests that these groups already had high fertility when family planning services became available and that this high fertility then became an inducement to acccept contraception. The pattern of relationship is not yet clear for the $20{\sim}29$ year group. Similar interactions are observed for the other indices of modernity and are discussed. The thirteen variables together can account for a maximum of about 40% of the variance in the number of live births in the age group $30{\sim}39$, and for lesser amounts of variance in other age and fertility groupings.

• Archives of Plastic Surgery
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• v.38 no.4
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• pp.438-444
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• 2011

Purpose: Adipose-derived stromal cells (ASCs) are readily harvested from lipoaspirated tissue or subcutaneous adipose tissue fragments. The stromal vascular fraction (SVF) is a heterogeneous set of cell populations that surround and support adipose tissue, which includes the stromal cells, ASCs, that have the ability to differentiate into cells of several lineages and contains cells from the microvasculature. The mechanisms that drive the ASCs into the osteoblast lineage are still not clear, but the process has been more extensively studied in bone marrow stromal cells. The purpose of this study was to investigate the osteogenic capacity of adipose derived SVF cells and evaluate bone formation following implantation of SVF cells into the bone defect of human phalanx. Methods: Case 1 a 43-year-old male was wounded while using a press machine. After first operation, segmental bone defects of the left 3rd and 4th middle phalanx occurred. At first we injected the SVF cells combined with demineralized bone matrix (DBM) to defected 4th middle phalangeal bone lesion. We used P (L/DL)LA [Poly (70L-lactide-co-30DL-lactide) Co Polymer P (L/DL)LA] as a scaffold. Next, we implanted the SVF cells combined with DBM to repair left 3rd middle phalangeal bone defect in sequence. Case 2 was a 25-year-old man with crushing hand injury. Three months after the previous surgery, we implanted the SVF cells combined with DBM to restore right 3rd middle phalangeal bone defect by syringe injection. Radiographic images were taken at follow-up hospital visits and evaluated radiographically by means of computerized analysis of digital images. Results: The phalangeal bone defect was treated with autologous SVF cells isolated and applied in a single operative procedure in combination with DBM. The SVF cells were supported in place with mechanical fixation with a resorbable macroporous sheets acting as a soft tissue barrier. The radiographic appearance of the defect revealed a restoration to average bone density and stable position of pharyngeal bone. Densitometric evaluations for digital X-ray revealed improved bone densities in two cases with pharyngeal bone defects, that is, 65.2% for 4th finger of the case 1, 60.5% for 3rd finger of the case 1 and 60.1% for the case 2. Conclusion: This study demonstrated that adipose derived stromal vascular fraction cells have osteogenic potential in two clinical case studies. Thus, these reports show that cells from the SVF cells have potential in many areas of clinical cell therapy and regenerative medicine, albeit a lot of work is yet to be done.

• Journal of Chest Surgery
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• v.46 no.5
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• pp.340-345
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• 2013

Background: This study aims to evaluate whether or not the method of right vertical axillary minithoracotomy (RVAM) is preferable to and as reliable as conventional sternotomy surgery, and also assesses its cosmetic results. Methods: Thirty-three patients (7 males, 26 females) with atrial septal defect were admitted to the Cardiovascular Surgery Clinic of Cukurova University from December 2005 until January 2010. The patients' ages ranged from 3 to 22. Patients who underwent vertical axillary minithracotomy were assigned to group I, and those undergoing conventional sternotomy, to group II. Group I and group II were compared with regard to the preoperative, perioperative and postoperative variables. Group I included 12 females and 4 males with an average age of $16.5{\pm}9.7$. Group II comprised 14 female and 3 male patients with an average age of $18.5{\pm}9.8$ showing similar features and pathologies. The cases were in Class I-II according to the New York Heart Association (NYHA) Classification, and patients with other cardiac and systemic problems were not included in the study. The ratio of the systemic blood flow to the pulmonary blood flow (Qp/Qs) was $1.8{\pm}0.2$. The average pulmonary artery pressure was $35{\pm}10$ mmHg. Following the diagnosis, performing elective surgery was planned. Results: No significant difference was detected in the average time of the patients' extraportal circulation, cross-clamp and surgery (p>0.05). In the early postoperative period of the cases, the duration of mechanical ventilator support, the drainage volume in the first 24 hours, and the hospitalization time in the intensive care unit were similar (p>0.05). Postoperative pains were evaluated together with narcotic analgesics taken intravenously or orally. While 7 cases (43.7%) in group I needed postoperative analgesics, 12 cases (70.6%) in group II needed them. No mortality or major morbidity has occurred in the patients. The incision style and sizes in all of the patients undergoing RVAM were preserved as they were at the beginning. Furthermore, the patients of group I were mobilized more quickly than the patients of group II. The patients of group I were quite pleased with the psychological and cosmetic results. No residual defects have been found in the early postoperative period and after the end of the follow-up periods. All of the patients achieved functional capacity per NYHA. No deformation of breast growth has been detected during 18 months of follow-up for the group I patients, who underwent RVAM. Conclusion: To conclude, the repair of atrial septal defect by RVAM, apart from the limited working zone for the surgeon in these pathologies as compared to sternotomymay be considered in terms of the outcomes, and early and late complications. And this has accounted for less need of analgesics and better cosmetic results in recent years.

• Journal of the Korean Geotechnical Society
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• v.26 no.6
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• pp.29-38
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• 2010

Micro-piles have been used to increase the bearing capacity or to restrain settlement of existing shallow foundation. Recently, micro-piles are used to support the shallow foundation, to stabilize the slope and to resist the sliding of retaining wall. Using the micro-piles in geotechnical engineering, some investigators have studied the effective installing method by model test or field test. But most of previous studies are chiefly focused on the micro-piles in sand or clay layer. If a rock layer exists in soil, the installing length of micro-piles may be determined by the depth of rock layer. In this case, the stiffness of pile may be changed by the installing length of pile, and so the installing method has to be altered by the changed stiffness of pile. Model tests have been conducted to study the installation method of micro-pile in soil with rock layer. As a result, when the ratio of length of pile is below 50 ($L/d{\leq}50$), installing of micro-piles in vertical position is effective regardless of the depth of rock layer. If the depth of rock layer is deeper than soil failure zone and the ratio of the length of pile exceeds 50 (L/d>50), installing of the micro-piles in sloped position is effective.

• International Commerce and Information Review
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• v.19 no.2
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• pp.213-236
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• 2017

World trade has entered a stagnant state, protection trade measures are spread due to delayed economic recovery in developed countries, sluggish investment in emerging economies such as China, economic recession in resource exporting countries, and geopolitical and political uncertainties along with the election period in the US and other major industrialized countries. Thus, in the economic structure of our country with a focus on export, for small and medium enterprises to grow, efforts for having various markets are necessary. The importance of the trade insurance system, which can support the risk management of enterprises, is emphasized by the fact that the majority of SME exporters have a risk management level and a lack of corporate capacity to enter the global market. This study was surveyed with 87 small and medium export companies in South Korea. The purpose of this study is to verify the effect relationship how service quality of trade insurance and utilization of trade insurance impact on the risk management of trade payment and export performance. The research hypothesis and model was derived from the basis of existing theory and empirical research, and obtained the following results. Firstly, Service Quality of Trade Insurance showed positive (+) effect on Export Performance. Secondly, Utilization of Trade Insurance showed positive (+) effect on Risk Management of Trade Payment. Thirdly, Risk Management of Trade Payment showed positive (+) effect on Export Performance. This study is differentiated from previous research information by empirically evaluating the relationship between the risk management of trade payment and export performance through utilization of trade insurance. This study contributed to academic by examining the research on the risk management of trade insurance and also practically suggested the direction how small and medium export company is to take the advantage of the trade insurance.

• Applied Chemistry for Engineering
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• v.8 no.2
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• pp.204-210
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• 1997

Zeolite 4A-impregnated complex molecular sieve was prepared by hydrothermal reaction after aluminosilicate gel was penetrated into the pore of activated carbon granule. The crystals of zeolite 4A mainly were formed in the macropore of activated carbon, and their average diameter is $0.8{\mu}m$. The pore volume of activated carbon granule is $0.67m{\ell}/g$, and the pore volume of the sample including 21.6wt% of zeolite 4A crystal is $0.41m{\ell}/g$ decreasing the pore volume by 40% due to the crystallization of zeolite 4A crystals on the internal surface of activated carbon. The calcium ion exchange capacity of zeolite 4A-impregnated sample is 320mg $CaCO_3/g$ zeolite, and this value is almost the same as that of zeolite 4A powder. The crystal of zeolite 4A was not separated from the support of activated carbon granule in the course of ultrasonic dispersion. The adsorption isotherm of water on zeolite 4A-impregnated sample shows the intermediate shape between types, I and III. In addition, zeolite 4A-impregnated sample shows the hydrophilic and hydrophobic properties simultaneously.

• Proceedings of the Korean Vacuum Society Conference
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• 2012.08a
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• pp.269-269
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• 2012

A new ion source has been designed, fabricated, and installed at the NBTS (Neutral Beam Test Stand) at the KAERI (Korea Atomic Energy Research Institute) site. The goalis to provide a 100 keV, 2MW deuterium neutral beam injection as an auxiliary heating of KSTAR (Korea Super Tokamak Advanced Research). To cope with power demand, an ion current of 50 A is required considering the beam power loss and neutralization efficiency. The new ion source consists of a magnetic cusp bucket plasma generator and a set of tetrode accelerators with circular copper apertures. The plasma generator for the new ion source has the same design concept as the modified JAEA multi-cusp plasma generator for the KSTAR prototype ion source. The dimensions of the plasma generator are a cross section of $59{\times}25cm^2$ with a 32.5 cm depth. The anode has azimuthal arrays of Nd-Fe permanent magnets (3.4 kG at surface) in the bucket and an electron dump, which makes 9 cusp lines including the electron dump. The discharge properties were investigated preliminarily to enhance the efficiency of the beam extraction. The discharge of the new ion source was mainly controlled by a constant power mode of operation. The discharge of the plasma generator was initiated by the support of primary electrons emitted from the cathode, consisting of 12 tungsten filaments with a hair-pin type (diameter = 2.0 mm). The arc discharge of the new ion source was achieved easily up to an arc power of 80 kW (80 V/1000 A) with hydrogen gas. The 80 kW capacity seems sufficient for the arc power supply to attain the goal of arc efficiency (beam extracted current/discharge input power = 0.8 A/kW). The accelerator of the new ion source consists of four grids: plasma grid (G1), gradient grid (G2), suppressor grid (G3), and ground grid (G4). Each grid has 280 EA circular apertures. The performance tests of the new ion source accelerator were also finished including accelerator conditioning. A hydrogen ion beam was successfully extracted up to 100 keV /60 A. The optimum perveance is defined where the beam divergence is at a minimum was also investigated experimentally. The optimum hydrogen beam perveance is over $2.3{\mu}P$ at 60 keV, and the beam divergence angle is below $1.0^{\circ}$. Thus, the new ion source is expected to be capable of extracting more than a 5 MW deuterium ion beam power at 100 keV. This ion source can deliver ~2 MW of neutral beam power to KSTAR tokamak plasma for the 2012 campaign.

• Geomechanics and Engineering
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• v.13 no.2
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• pp.195-215
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• 2017

This paper proposes gob-side entry retaining by roof break and filling in thick-layer soft rock conditions based on the thick-layer soft rock roof strata migration law and the demand for non-pillar gob-side entry retaining projects. The functional expressions of main roof subsidence are derived for three break roof direction conditions: lateral deflection toward the roadway, lateral deflection toward the gob and vertically to the roof. These are derived according to the load-bearing boundary conditions of the main roadway roof stratum. It is concluded that the break roof angle is an important factor influencing the stability of gob-side entry retaining surrounding rock. This paper studies the stress distribution characteristics and plastic damage scope of gob-side entry retaining integrated coal seams, as well as the roof strata migration law and the supporting stability of caving structure filled on the break roof layer at the break roof angles of $-5^{\circ}$, $0^{\circ}$, $5^{\circ}$, $10^{\circ}$ and $15^{\circ}$ are studied. The simulation results of numerical analysis indicate that, the stress concentration and plastic damage scope to the sides of gob-side entry retaining integrated coal at the break roof angle of $5^{\circ}$ are reduced and shearing stress concentration of the caving filling body has been eliminated. The disturbance of coal mining to the roadway roof and loss of carrying capacity are mitigated. Field tests have been carried out on air-return roadway 5203 with the break roof angle of $5^{\circ}$. The monitoring indicates that the break roof filling section and compaction section are located at 0-45 m and 45-75 m behind the working face, respectively. The section from 75-100 m tends to be stable.