• Advances in concrete construction
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• v.5 no.5
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• pp.513-537
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• 2017

In this study, the fracture toughness $K_{IC}$ of high performance concrete (HPC) was investigated by conducting three-point bending tests on a total of 240 notched beams of $500mm{\times}100mm{\times}100mm$ subjected to heating temperatures up to $450^{\circ}C$ with exposure times up to 16 hours and various heating and cooling rates. For a heating rate of $3^{\circ}C/min$, $K_{IC}$ for the hot concrete sustained a monotonic decrease trend with the increasing heating temperature and exposure time, from $1.389MN/m^{1.5}$ at room temperature to $0.942MN/m^{1.5}$ at $450^{\circ}C$ for 4-hour exposure time, $0.906MN/m^{1.5}$ for 8-hour exposure time and $0.866MN/m^{1.5}$ for 16-hour exposure time. For the cold concrete, $K_{IC}$ sustained a two-stage decrease trend, dropping slowly with the heating temperature up to $150^{\circ}C$ and then rapidly down to $0.869MN/m^{1.5}$ at $450^{\circ}C$ for 4-hour exposure time, $0.812MN/m^{1.5}$ for 8-hour exposure time and $0.771MN/m^{1.5}$ for 16-hour exposure time. In general, the $K_{IC}$ values for the hot concrete up to $200^{\circ}C$ were larger than those for the cold concrete, and an inverse trend was observed thereafter. The increase in heating rate slightly decreased $K_{IC}$, and at $450^{\circ}C$ $K_{IC}$ decreased from $0.893MN/m^{1.5}$ for $1^{\circ}C/min$ to $0.839MN/m^{1.5}$ for $10^{\circ}C/min$ for the hot concrete and from $0.792MN/m^{1.5}$ for $1^{\circ}C/min$ to $0.743MN/m^{1.5}$ for $10^{\circ}C/min$ for the cold concrete after an exposure time of 16 hours. The increase in cooling rate also slightly decreased $K_{IC}$, and at $450^{\circ}C$ $K_{IC}$ decreased from $0.771MN/m^{1.5}$ for slow cooling to $0.739MN/m^{1.5}$ for fast cooling after an exposure time of 16 hours. The fracture energy-based fracture toughness $K_{IC}$' was also assessed, and similar decrease trends with the heating temperature and exposure time existed for both hot and cold concretes. The relationships of two fracture toughness parameters with the weight loss and the modulus of rapture were also evaluated.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.49 no.11
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• pp.893-900
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• 2021

In this study, air density in a narrow test section is measured using a laser absorption spectroscopy system that detects oxygen absorption lines. An absorption line pair at 13156.28 and 13156.62 cm^-1 are detected. A gas chamber with a height of 40 mm is used as a narrow test section. A triangular spiral-shaped laser path is applied in the gas chamber to amplify absorption strength by extending laser beam path length. A well-known logarithm amplifier and a secondary amplifier are used to electrically amplify absorption signal. An AC-coupling is applied after the logarithm amplifier for signal saturation prevention and noise suppression. Procedure of calculating spectral absorbance from output signal is introduced considering the logarithm amplifier circuit configuration. Air density is determined by fitting the theoretically calculated spectral absorbance to the measured spectral absorbance. Test conditions with room temperature and a pressure range of 10~100 kPa are made in a gas chamber using a Bourdon pressure gauge. It is confirmed that air density in a narrow test section can be measured within a 16 % error through absorption signal amplification using a triangular spiral-shaped beam path and a logarithm amplifier.

• Journal of the Korean Wood Science and Technology
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• v.49 no.5
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• pp.462-470
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• 2021

To find out the wood species used in national wood structures in the late Joseon Dynasty, 11 volumes of Yeonggeon-Uigwes were reviewed. It was confirmed that the wood was mainly used for the repair and restoration of palaces, shrines, and fortresses. In the 17th to 20th centuries, the wood species specified in Yeonggeon-Uigwes have revealed either hardwood or softwood. As hardwood species, Juglans mandshurica, Zelkova serrata, Fraxinus rhynchophylla, Betula schmidtii, Paulownia coreana, or Quercus spp. (Quercus aliena; Q, variabilis; Q, dentata; Q, acutissima; Q, mongolica; Q, serrata) were used. As softwood species, Pinus densiflora and Pinus koraiensis were used. Investigation of the wood species is important part because the same species is required as a principle when reparing cultural heritage. In this study, the anatomical images of the wood species were investigated for some samples which were taken from the same species that has been stored in the wood specimen room of the National Institute of Forest Science, instead of the actual wood material used. It was possible to find out the wood species of each member in the wooden cultural heritage buildings by reviewing the Yeonggeon-Uigwes in the late Joseon Dynasty, and the anatomical images of the wood species required for determining the wood species in the repair or restoration of the buildings.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.22 no.4
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• pp.90-98
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• 2021

Since 2017, the Occupational Safety and Health Act has been fully applied to school food services, and risk assessments have been implemented since 2019. The introduction was slow compared to other industries and was evaluated by non-professional nutritionists, so there was a limit to establishing the system. All schools under the Seoul Metropolitan Office of Education apply the KRAS every year in accordance with the OSH Act for school foodservice and a notice from the Ministry of Employment and Labor. A risk assessment is applied according to legal regulations. On the other hand, the effectiveness of risk assessment has been questioned because the frequency and intensity criteria of the risk are qualitative and subjective. Based on the accident statistics of catering workers, the frequency and intensity criteria of risk were presented quantitatively and objectively, and a risk assessment was conducted by applying a new calculation standard for some work during the catering service and compared with current risk assessment results. The risk was increased, and the improved effectiveness was confirmed by the specific suggestions for improvement. Thus, the pilot evaluation for the entire food service should be expanded, and the feasibility confirmed. The pilot evaluation should be applied to all schools to enhance the effectiveness and operability of the risk assessment.

• Korean Journal of Comparative Education
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• v.28 no.4
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• pp.221-248
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• 2018

The purpose of this study was to analyze the performance of the Daegu Happiness Competency Education Program. It was confirmed that students, parents, teachers, and education professions are aware of the middle and higher level of education for happiness in Daegu in terms of the formation and operation of the curriculum. There is no significant difference between students and parents in terms of average value, and teachers' perception level is relatively high, which is understandable in that teachers are the subjects of the curriculum organization and operation. In addition, there was no statistically significant difference between the parents and the school level, but there were significant differences between students and teachers. In particular, students' and teachers' perceptions were lowered as the number of schools increased, unlike the predictions. They showed the lowest results in the special schools, autonomous schools and special schools. The reason for this is that Daegu Happiness Competency Education was implemented in 2014, and it was because there was little room to recognize and accept the new curriculum due to the burden of college entrance examination or employment. In the future, it will naturally improve as the education process is settled, but here we can find suggestions for the establishment of Daegu Happiness Competency Education.

• Food Engineering Progress
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• v.13 no.1
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• pp.56-63
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• 2009

The aim of this study was to control the outbreak of food pathogen through quantitative microbial risk assessment (QMRA). We used Monte Calro Simulation (MCS) to predict contamination levels of Staphylococcus aureus on the raw materials, equipments and cook in Japanese restaurant located in Seoul. The result of sensitivity analysis showed that the most significant factor for the outbreak of food pathogen was consumption temperature and storage time. In shrimp and octopus sushi, 'consumption temperature' was the highest sensitivity value of 0.419 followed by 'storage time' of 0.374. To increase safety of sushi, consumers should have sushi as soon as possible after cooking. In sushi 'storage time after cooking' was determined as Critical Control Point (CCP). To determine Control Limit (CL), Scenario Analysis (SA) was carried out. In sushi, SA was carried out using storage time as a unit condition. Safety level of S. aureus was set lower than 5 log CFU/g. After 2 hr 'storage time' the number of S. aureus increased to 3.908 log CFU/g. Therefore, 'storage time' of sushi was set as CL in case of room temperature storage.

• Food Engineering Progress
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• v.15 no.3
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• pp.230-234
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• 2011

The objective of this study was to optimize the thermal condition and determine the shelf life of heated Chunbokjang product. The optimum thermal condition of heated Chunbok-jang product was determined by sensory test, and heat penetration curve was obtained by Thermal Microprocessor. Sterilization time was a 21~23 min until $F_0$ value reached 9 min, depending upon the number of abalone. As solid content was reduced and temperature of sterilization was increased, the thermal death time was decreased. The score of sensory test indicated that there was no significant difference in flavor of heated Chunbok-jang product made at different sterilization temperatures (110, 121.1, 125, and $130^{\circ}C$). Heated Chunbok-jang product, however, sterilized at $125^{\circ}C$ showed the highest score in texture and taste values. Salinity and pH were not changed during seven month storages, but texture became firmer, and any microorganism had not been detected from the heated chunbok-jang product during these periods. As a result of storage experiment, the shelf-life of heated Chunbok-jang product was 3-month at room temperature.

• Journal of Trauma and Injury
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• v.32 no.1
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• pp.1-7
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• 2019

Purpose: The present study aimed to evaluate the influence of how the trauma care system applied on the management of trauma patient within the region. Methods: We divided the patients in a pre-trauma system group and a post-trauma system group according to the time when we began to apply the trauma care system in the Halla Hospital after designation of a trauma center. We compared annual general characteristics, injury severity score, the average numbers of the major trauma patients, clinical outcomes of the emergency department, and mortality rates between the two groups. Results: No significant differences were found in the annual patients' average age ($54.1{\pm}20.0$ vs. $52.8{\pm}18.2$, p=0.201), transportation pathways (p=0.462), injury mechanism (p=0.486), injury severity score (22.93 vs. 23.96, p=0.877), emergency room (ER) stay in minutes (199.17 vs. 194.29, p=0.935), time to operation or procedure in minutes (154.07 vs. 142.1, p=0.767), time interval to intensive care unit (ICU) in minutes (219.54 vs. 237.13, p=0.662). The W score and Z score indicated better outcomes in post-trauma system group than in pre-trauma system group (W scores, 2.186 vs. 2.027; Z scores, 2.189 vs. 1.928). However, when analyzing survival rates for each department, in the neurosurgery department, in comparison with W score and Z score, both W score were positive and Z core was higher than +1.96. (pre-trauma group: 3.426, 2.335 vs. post-trauma group: 4.17, 1.967). In other than the neurosurgery department, W score was positive after selection, but Z score was less than +1.96, which is not a meaningful outcome of treatment (pre-trauma group: -0.358, -0.271 vs. post-trauma group: 1.071, 0.958). Conclusions: There were significant increases in patient numbers and improvement in survival rate after the introduction of the trauma system. However, there were no remarkable change in ER stay, time to ICU admission, time interval to emergent procedure or operation, and survival rates except neurosurgery. To achieve meaningful survival rates and the result of the rise of the trauma index, we will need to secure sufficient manpower, including specialists in various surgical area as well as rapid establishment of the trauma center.

• Journal of Dental Anesthesia and Pain Medicine
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• v.19 no.1
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• pp.55-66
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• 2019

Background: Postoperative nausea and vomiting (PONV) frequently occurs following bimaxillary orthognathic surgeries. Compared to opioids, Nefopam is associated with lower incidences of PONV, and does not induce gastrointestinal tract injury, coagulopathy, nephrotoxicity, or fracture healing dysfunction, which are common side effects of Nonsteroidal anti-inflammatory drugs. We compared nefopam- and fentanyl-induced incidence of PONV in patients with access to patient-controlled analgesia (PCA) following bimaxillary orthognathic surgeries. Methods: Patients undergoing bimaxillary orthognathic surgeries were randomly divided into nefopam and fentanyl groups. Nefopam 120 mg or fentanyl $700{\mu}g$ was mixed with normal saline to a final volume of 120 mL. Patients were given access to nefopam or fentanyl via PCA. Postoperative pain intensity and PONV were measured at 30 minutes and 1 hour after surgery in the recovery room and at 8, 24, 48, and 72 hours after surgery in the ward. The frequency of bolus delivery was compared at each time point. Results: Eighty-nine patients were enrolled in this study, with 48 in the nefopam (N) group and 41 in the fentanyl (F) group. PONV occurred in 13 patients (27.7%) in the N group and 7 patients (17.1%) in the F group at 8 hours post-surgery (P = 0.568), and there were no significant differences between the two groups at any of the time points. VAS scores were $4.4{\pm}2.0$ and $3.7{\pm}1.9$ in the N and F groups, respectively, at 8 hours after surgery (P = 0.122), and cumulative bolus delivery was $10.7{\pm}13.7$ and $8.6{\pm}8.5$, respectively (P = 0.408). There were no significant differences in pain or bolus delivery at any of the remaining time points. Conclusion: Patients who underwent bimaxillary orthognathic surgery and were given nefopam via PCA did not experience a lower rate of PONV compared to those that received fentanyl via PCA. Furthermore, nefopam and fentanyl did not provide significantly different postoperative pain control.

• Journal of the Korea Convergence Society
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• v.10 no.1
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• pp.339-351
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• 2019

This study was conducted to identify the factors associated with the ruptured intracranial aneurysm (RIA) among demographic, admission to hospital, clinical, aneurysym itself and lifestyle characteristics. Medical records of RIA patients and un-RIA patients which had been admitted to undergo treatment including surgery (From January to December 2016) were included into data analysis. Multiple logistic regression showed that two and more than warning signs (14.14 (CI: 1.25-159.40)) indicated the greatest odds ratio with RIA, was followed by headache more than 3 scores (13.95 (CI: 3.68-52.83)), the admission via emergency room (13.62 (CI: 4.85-38.26)), single marital status (9.72 (CI: 2.22-42.49)), 1 mmHg increased systolic blood pressure (1.04 (CI: 1.01-1.08)), 1 score increased GCS (0.58 (CI: 0.37-0.90)), arrythmia finding in electrocardiogram (3.70 (CI: 1.22-11.22)) and increased age (0.95 (CI: 0.91-0.99)). The risk groups having factors associated with RIA were identified. Preventive activities including routine assessment should be done before developing the rupture and urgent care should be needed after developing the rupture for risk groups.