The O2 and CO2 concentrations in controlled atmosphere (CA) rooms are determined by the respiration of produce like apples and the airtightness of the CA room, with gas in the CA room controlled by O2 and CO2 removal as well as respiration (CO2 increase and O2 decrease). The purpose of this study was to evaluate the validity of the gas exchange model for O2 removal, CO2 removal, the rate of O2 decrease and CO2 increase by respiration of apples, and airtightness of the CA room. It took 17.5 hours to reduce O2 concentration from 20.9% to 2.0% after loading 4.3 tons of Fuji apples into the CA room, which was 4.2 hours longer than the 13.3 hours of the model formula. After the CO2 concentration rose to 0.5% due to respiration, it took 4.7 hours to lower the CO2 concentration to 0.2%, which was 0.6 hours longer than that of the model equation. The rate of CO2 increase by respiration was 0.021%/ h, which was similar to the model equation (0.017%/h). Also after 4.7 hours, the O2 concentration decreased by 0.1% which was also in line with the model equation (0.13%/h).

The variations of internal temperature, relative humidity (RH) and gas concentration in the pallet modified atmosphere package (MAP), using polyamide (PA) film and linear low density polyethylene (LLDPE) film, were investigated to extend the shelf life of tomatoes and paprikas. The temperature and RH inside the MAP were higher than that in the cold room, but there was no water condensation inside the MA film. The ethylene concentration in the MAP was maintained below 10 ppm. Oxygen level was stabilized at 2 to 5% during the storage and carbon dioxide level was also stabilized at 15 to 20%. The weight loss of the MAP tomatoes and paprikas was lower than that of the control because the RH in the pallet MAP was higher than that of the cold room. The fungal decay rate in the pallet MAP was also lower than that in the control due to a low oxygen concentration rate. There were no significant differences in the soluble solids, titratable acidity and Hunter’s color, but differences did exist in the hardness between the MAP and the control. So, this pallet MAP method was effective at extending the shelf life of tomatoes and paprikas considering the weight loss, fungal decay and hardness.

반도체용 초순수를 생산하는 공정에서 수질관리를 위해 카트리지 필터, 한외여과막, 역삼투막, 탈기막, 이온교환막, 최종생산수용 한외여과막 등 다양한 종류의 분리막이 적용되고 있다. 분리막 공정은 종래기술과 비교하여 동등이상의 성능과 운전의 용이함과 설치면적의 최소화 등 부수적인 장점을 가지고 있다. 유입수의 수질에 따라 전처리 필터의 종류 및 기능이 결정되며, 최종수의 폴리싱 부담을 줄이기 위한 분리막 공정의 구성 등이 중요하다. 본 연구에서는 반도체용 초순수 실증파일럿플랜트의 공정 최적화를 위해 분리막 공정의 구성 및 운전방법에 따른 성능 등을 평가하는 연구를 진행하였다.

In this study, two types of SKD61 tool-steel samples are built by a selective laser melting (SLM) process using the different laser scan speeds. The characteristics of two kinds of SKD61 tool-steel powders used in the SLM process are evaluated. Commercial SKD61 tool-steel power has a flowability of 16.68 sec/50 g and its Hausner ratio is calculated to be 1.25 by apparent and tapped density. Also, the fabricated SKD61 tool steel powder fabricated by a gas atomization process has a flowability of 21.3 sec/50 g and its Hausner ratio is calculated to be 1.18. Therefore, we confirmed that the two powders used in this study have excellent flowability. Samples are fabricated to measure mechanical properties. The highest densities of the SKD61 tool-steel samples, fabricated under the same conditions, are 7.734 g/cm³ (using commercial SKD61 powder) and 7.652 g/cm3 (using fabricated SKD61 powder), measured with Archimedes method. Hardness is measured by Rockwell hardness testing equipment 5 times and the highest hardnesses of the samples are 54.56 HRC (commercial powder) and 52.62 HRC (fabricated powder). Also, the measured tensile strengths are approximately 1,721 MPa (commercial SKD61 powder) and 1,552 MPa (fabricated SKD61 powder), respectively.

PURPOSES: The purpose of this research is to analyze the characteristics of panels that affect the evaluating results of riding quality and to evaluate the appropriateness of roughness management criteria based on ride comfort satisfaction. METHODS: In order to analyze the influence of panel characteristics of riding quality, 33 panels, consisting of civilians and experts, were selected. Also, considering the roughness distribution of the expressway, 35 sections with MRI ranging from 1.17 m/km to 4.65 m/km were selected. Each panel boarded a passenger car and evaluated the riding quality with grades from 0 to 10, and assessed whether it was satisfied or not. After removing outlier results using a box plot technique, 964 results were analyzed. An ANOVA was conducted to evaluate the effects of panel expertise, age, driving experience, vehicle ownership, and gender on the evaluation results. In addition, by using the receiver operating characteristics (ROC) curve, the MRI value, which can most accurately evaluate the satisfaction with riding quality, was derived. Then, the compatibility of MRI was evaluated using AUC as a criterion to assess whether the riding quality was satisfactory. RESULTS: Only the age of the panel participants were found to have an effect on the riding quality satisfaction. It was found that satisfaction with riding quality and MRI are strongly correlated. The satisfaction rate of roughness management criteria on new (MRI 1.6 m/km) and maintenance (MRI 3.0 m/km) expressways were 95% and 53%, respectively. As a result of evaluating the roughness management criteria by using the ROC curve, it was found that the accuracy of satisfaction was the highest at MRI 3.1-3.2 m/km. In addition, the AUC of the MRI was about 0.8, indicating that the MRI was an appropriate index for evaluating the riding quality satisfaction. CONCLUSIONS: Based on the results, the distribution of the panels’age should be considered when panel rating is conducted. From the results of the ROC curve, MRI of 3.0 m/km, which is a criterion of roughness management on maintenance expressways, is considered as appropriate.

목 적：MRI Upper Extremity(elbow, forearm) 촬영 시 피사체가 bore center에서 벗어나는 정도가 클 수 밖에 없다. 일반적으로 bore의 isocenter에서 촬영하는 것이 자기장의 균일도가 높아 영상의 SNR이 높 을 것이다. 본 연구에서는 Upper extremity 촬영 시 isocenter에서 벗어나는 정도에 따라 테이블을 기 준으로 피사체의 수직 위치변화에 따른 MRI영상의 SNR을 비교해 평가하고자한다. 대상 및 방법：원기둥모양의 water phantom을 MRI bore의 가장자리에서 1)테이블에 붙여서, 2) 테이블에서 11cm 올려서, 촬영하였다. 장비는 Siemens사 Verio 3T장비를 이용하였다. Flexible Large Coil을 사 용하여 T2 TSE sequence를 TR = 4560ms, TE = 76ms, slice thickness = 3mm, FOV = 120mm의 파라미터로 두 경우 모두 일치시켜서 촬영하였다. 결과의 공정함을 가하기 위해 prescan은 자동으로 수행하게 하였다. 영상을 평가하는 방법으로 두 영상의 중앙지점, 가장자리지점 12개 지점의 SNR을 측정 하여 정량적 평가를 하였다. 두 영상간의 SNR 차이가 통계적으로 유의미한지 확인하기 위해 Microsoft Excel의 paired t-test를 이용하였고, 이 때 유의성을 판단하는 기준은 p<0.05으로 하였다. 추가적으로 실제 flip angle이 피사체에 어떻게 들어갔는지를 확인하기 위해 double angle method를 이용하여 B1 mapping을 하였다. B1 map을 얻기 위한 촬영방법은 똑같은 위치에서 Flash sequence를 사용하여 TR = 1000 ms, TE = 3ms, flip angle 45도의 파라미터로 촬영하고, 같은 조건에서 flip angle 90도로 영상을 얻었다. 45도로 얻은 영상과 90도로 얻은 영상을 통해 double angle method를 이용하여 B1 map을 구한 후, B1의 균일성을 평가하였다. 결 과：정량적 평가를 통해 영상의 SNR 측정지점 12개 지점에 대한 검정을 한 결과 통계적으로 유의하게 테이 블에서 11cm를 올려서 촬영한 경우에 SNR이 더 높았다 (p<0.05). B1 map 촬영결과는 11cm를 올려서 촬영한 영상이 실제 가해지는 flip angle이 정상적으로 들어가고, 테이블에 붙여서 촬영한 영상은 더 높 은 flip angle이 들어간 것을 알 수 있었다. 이를 통해 T2 TSE를 촬영 시 테이블에 붙여서 촬영한 영상은 excitation및 refocusing RF의 flip angle이 의도대로 들어가지 못해 SNR이 떨어졌을 것임을 추측해볼 수 있다. 결 론：일반적으로 MRI 촬영 시 bore center에서 촬영하지만 Upper Extremity 검사 시 bore의 가장자리로 갈 수 밖에 없다. 3T장비에서 flexible coil을 이용하여 elbow, forearm등의 검사를 할 때 테이블에서 올려 검사 하게 되면 원하는 flip angle이 정상적으로 들어가서 SNR이 높은 영상을 얻을 수 있을 것 이라고 사료된다. 만약, 피사체를 올리기 어려운 경우라면 transmit gain이 제대로 조정이 되었는지 확 인해 볼 필요가 있다.

PURPOSES : The frequency and severity of natural disasters such as torrential rain or typhoons have become increasingly significant worldwide. Events such as summer typhoons and localized torrential downpour can cause severe damages to a residential area and road networks, resulting in serious harm to the daily lives of people, especially in rural areas by isolating residents from road networks. An immediate and emergency repair technology for the collapsed road networks is urgently needed. This study introduces a new technology to repair road bases or slopes. METHODS: The development of new technology for emergency and permanent repair consists of first, packing of cement paste-coated gravel, second, combining appropriate equipment, and third, conducting a field applicability test. In this research, the compressive strength of cement pastecoated gravel, gravel-netting concrete properties, and packing efficiency were determined, and a full scale field mock-up test was carried out. RESULTS : The compressive strength of the cement paste-coated gravel concrete satisfied the required limit for road base of 5 MPa after 7 days. With appropriate netting materials and packing size, gravel-netting concrete was successful up to a slope of 1:1.5. The full scale field mockup test showed efficiency in the field and penetration resistance performance. CONCLUSIONS: The new technology of emergency and permanent repair for damaged road bases and slopes, introduced in this study, showed satisfactory performance. The technology is expected to be applied in the field when construction procedures and quality specifications are made.

The identification of damping ratios in buildings is a well-known problem and appears to be of important and crucial interest in the safety and serviceability design. When compared to an estimation of the stiffness, i.e. natural frequency, and mass, the damping ratio is the most difficult quantity to determine. Many previous studies have examined the characteristics of damping ratios from ambient vibration, but the measurement time is roughly within 2 hours. In this paper, characteristics of damping ratios and natural frequencies of 4 story RC building were investigated using long-term ambient vibration. Free vibrations were obtained using random decrement technique, and damping ratios were evaluated by the envelop function, continuous wavelet transform, and logarithmic decrement. It was found that although the natural frequencies show little variations with time, the damping ratios show some variations with time and the largest variations found in the damping ratios obtained from the continuous wavelet transform. The damping ratios from the envelop function showed the smallest mean and standard deviation. And the probability distribution of damping ratios seems to follow the logarithmic normal distribution.

담낭암은 발생 빈도가 높지 않으며, 예후가 매우 불량한 암으로 알려져 있다. 근치적 치료법은 수술적 절제가 유일하나, 수술이 불가능한 진행성 병기에서 진단되는 경우가 많아 실제로 근치적 수술이 가능한 경우는 많지 않다. 복통을 주소로 내 원한 49세 환자가 전산화단층촬영에서 담낭암이 진단되었고, 자기공명췌담관조영술 및 양전자컴퓨터단층촬영 결과 수술이 불가능한 진행성 병기로 확인되어 여러차례 담도 감압술과 항암 치료를 받았으며, 치료 중 시행한 반응 평가 검사에서 수술이 가능한 상태로 판단되어 우측 문맥술로 간 용적을 증가시킨 후 성공적으로 근치적 목적의 수술을 시행받았다. 첫 진단시 수술이 불가능하였던 진행성 담낭암 환자가 고식적 목적의 항암화학요법과 담관배액술을 여러 차례에 걸쳐 시행받은 이후 암의 범위가 줄어들어 성공적으로 근치적 수술을 시행한 증례를 경험하여 이를 문헌고찰과 함께 보고하는 바이다.

With land-use (cover) and water quality, the distributional characteristics of epilithic diatom communities were studied with 193 samples from estuaries of Korean peninsula between 2015 and 2016. Of total 394 taxa classified, Nitzschia perminuta (19.6%) and N. inconspicua (14.0%) were the 1st and 2nd dominant species. Using a cluster analysis, the epilithic diatom communities of Korean estuaries were divided into four groups (G1-G4). Ecological characteristics of each group were followed: G1 was located in estuaries of the East Sea, and characterized by high forest land-use and high DO and low nutrients; G2 was the eastern part of the South Sea, and characterized by low turbidity and nutrients; G3 was the western part of the South Sea, and characterized by high agriculture, low electric conductivity and low salinity; G4 was the Yellow Sea, and characterized by high nutrients. The environmental factors having significant correlation with diatom distributions were as follows: TN to G1, turbidity to G2, agriculture to G3, and TP to G4. Moreover, the important factors affecting the occurrence of indicator species were forest land-use for Fragilaria construens var. venter in G1, turbidity for Rhoicosphenia abbreviata in G2, urban land- use and total phosphorus (TP) for Bacillaria paradoxa and Hantzschia amphioxys of G3, and TP and turbidity for N. ovalis and Stephanodiscus invistatus of G4. These results collectively indicate that the distribution of epilithic diatom communities in Korean peninsula was largely effected by water quality and land cover/use.