• Korean Journal of Food Science and Technology
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• v.37 no.2
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• pp.321-327
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• 2005

Staphylococcus aureus is spread worldwide and can result in food poisoning outbreaks. Among samples collected from soil, water, protected houses, packing houses, employees, strawberries, and leaves, and analyzed for S. aureus contamination, 16% samples 'showed S. aureus contamination, particularly on employees' hands, scissors, and strawberries. Examination of enterotoxins A, B, and C genes of S. aureus by PCR revealed sea and seb in 92 and 38% of total strains, respectively, whereas sec was not detected. In conclusion, implementation of Good Agricultural Practice is necessary for preventing food-borne diseases of staphylococcal origin, thereby ensuring the safety of farm-to-table products.

• Journal of Food Hygiene and Safety
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• v.29 no.4
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• pp.253-259
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• 2014

This study was conducted to investigate survival of Bacillus cereus (B. cereus) on stainless steel and polyvinyl chloride (PVC) and its transfer from two material to lettuce. The stainless steel and PVC were innoculated with B. cereus and stored at 6 combination conditions (temperature : $20^{\circ}C$ and $30^{\circ}C$, relative humidity (RH) : 43%, 69%, and 100%). Although the total numbers of B. cereus at RH 43% and RH 69% were reduced by 3.53-4.00 log CFU/coupon within 24 h regardless of material type, the spore numbers of B. cereus was lasted at 3.0 log CFU/coupon. When two materials were stored at $30^{\circ}C$, RH 100%, the spore numbers of B. cereus was rapidly increased by 3.0 log CFU/coupon. In addition, the reduction rate of B. cereus was decreased in the presence of organic matter. Transfer rate of B. cereus from surface of stainless steel and PVC to lettuce was increased by 10 times in the presence of water on the lettuce surface. As a result of this study, the presence of B. cereus on produce contact surfaces can increase the risk of cross-contamination. Thus, it is important that the packing table and conveyer belt in post harvest facility should be properly washed and sanitized after working to prevent cross-contamination.

• Journal of the Korean Society of Food Culture
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• v.11 no.5
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• pp.699-710
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• 1996

The sacrificial foods using at 88 villages in Andong area where the village sacrificial rituals are performed, were investigated in 1994. The finding are as follows; 1. Since the village sacrificial rituals keep ancientry, white Baeksulki without any ingredients is used as Ddock (a steamed rice cake) in 74 villages, and in 5 villages the Baeksulki was served just in Siru (a tool used to prepare Ddock). The type of meat serving in rituals has been changing from large animal to small animal and the type of light from bowl-light to candle. 2. Though the ritual observes Confucianism style, memorial address was offered in 34 villages and only in 8 villages, liquor was served 3 times and the address was offered. In 60 villages, liquor was served only once, and calling village god, bowing twice, and burning memorial address paper were performed in order. Burning paper has been meaningful in rituals. 3. Tang (a stew) was served in 21 villages, and in 18 villages even Gook (a soup) was not used. The numbers of village which do not use cooked rice and Ddock are 14, respectively. 4. Fruits are essential in rituals foods. In 63 villages, 3 kinds of fruits are served and this is contrasted with even number of fruits in Bul-Chun-Wi Rituals. 5. In 25 villages, fish and meat are not served. As meat, chicken in 19 village are served. Meat Sikhae (a fermented rice beverage) prepared with meats or fish are served in 5 villages. Slice of dried meat is served in 73 villages commonly. 6. In gender of god for village shrine, woman in 43 villages, couple in 17 villages, man in 9 villages, mountain god in 2 villages, villages tree, etc were enshrined. In 52 villages liquor is served in rituals (liquor is used in 58 villages including serving god), in 28 villages sweet liquor (Gamju) is served for god (sweet liquor is used in 46 villages), and liquor, water, or sweet liquor is just displayed on table but not served in 8 villages. Incensing is found to be not common in village ritual, only in two villages it is performed. The most appropriate rituals food is thought to be pig for mountain god. Home dishes can not be used in village ritual and spoon is not used and chopstick is prepared from wild plant. Meat and fish are used in the raw.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.64 no.1
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• pp.1-17
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• 2019

A quantitative trait loci (QTL) analysis of traits related to heading and yield was performed develop rice cultivars that are both early maturing and panicle weight type varieties. Our analysis included 120 strains of the Cheongcheong Nagdong doubled haploid (CNDH) variety. An observational growth experiment was conducted to identify genetic agronomic traits of CNDH. Heading date, ten plant weight, moisture, thousand grain weight, and yield had a normal distribution based on the frequency distribution table of the observational growth data. The QTL analysis found one heading-related and nine yield-related QTLs. The LOD of 2.85 was the largest in QTLs for heading date (QHD), 5.39 in QTLs for ten plant weight (QTPW), 3.92 in QTLs for moisture (QM), 4.80 in QTLs for thousand grain weight (QTGW), and 3.7 in QTLs for yield (QY). Genomic analysis detected 58 candidate genes on chromosome 2, 3, 7, 8, and 10. Among those, we found Rcd1 protein and OsERF3 gene in QM, MtN3 and zinc finger protein genes in QTGW, and OsNAC3 protein gene in QY. If further analysis reveals the presence of genes related to water content, thousand grain weight or yield in the CNDH stains, we can develop a selection of varieties that will be capable of coping with climate change and will contribute to global food problems.

• Journal of the Korean Geotechnical Society
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• v.37 no.1
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• pp.29-41
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• 2021

Although underground works are essential to use underground spaces in urban areas efficiently, various damages caused by constructions have often occurred, making them major social problems. Since 2018, it is stipulated in the Special Act on Underground Safety Management that appropriate construction methods must be used in the design stage to prevent various damage cases. This Special Act includes establishing an area subject to underground safety impact assessment, analysis of ground and geological status, review of effects caused by changes in groundwater, review of ground safety, and establishment of measures to secure underground safety. This study area consists of various strata in order of landfill, sedimentary silt, sedimentary sand, sedimentary gravel, weathering zone, and foundation rock. Also, the slurry wall, a highly rigid underground continuous wall, was chosen as a construction method to consider high water table distribution and minimize the influence of the surroundings in this area. However, ground subsidence occurred on the road nearby in December 2019 due to the inflow of loosening soil to the construction area. Thus, several types of site investigations were conducted to suggest an appropriate analysis method and to find out loosed ground behavior and its area for the subsided site. As a result, new design soil properties were re-calculated, and the reinforcement measures were proposed through analytical verification.

• Journal of Korean Tunnelling and Underground Space Association
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• v.24 no.3
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• pp.263-278
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• 2022

This paper contains experimental study for the development and performance of TBM backfill material with thixotropic properties. The LW backfill material is widely applied to fill the cavity on the back side of the shield TBM excavation, but has disadvantages such as settlement caused by strength reduction, material separation by groundwater, and reduced plasticity. In this paper, laboratory tests and a model test were conducted to assess the performance of inorganic thixotropic backfill material proposed to improve these problems. The results of laboratory tests show that 1 hr-uniaxial compressive strength of ITB was 12 times higher than LW, and the rate of bleeding of 20 hr was 8.3 times lower, and the result of flow table test was more than 27 times higher. This result indicated that the inorganic thixotropic backfill material has superior properties to LW backfill in terms of strength reduction, material separation, and thixotropy. In the model experiment, a model injection device tester was manufactured and the injection performance and filling rate were verified. When material was injected in the water, it was visually checked whether material separation occurred, and it was confirmed that the filling rate was 96% or more. Comparison results with the test of LW and ITB materials was concluded that ITB can reduce the material separation by groundwater and the occurrence of tunnel cavity.

• Journal of the Korean Geotechnical Society
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• v.22 no.8
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• pp.107-118
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• 2006

Among a variety of influencing components, time-variant seepage and long-term underground motion are important to understand the abnormal behavior of tunnels. Excessiveness of these two components could be the direct cause of severe damage on tunnels, however, it is not easy to quantify the effect of these on the behavior of tunnels. These parameters can be estimated by using inverse methods once the appropriate relationship between inputs and results is clarified. Various inverse methods or parameter estimation techniques such as artificial neural network and least square method can be used depending on the characteristics of given problems. Numerical analyses, experiments, or monitoring results are frequently used to prepare a set of inputs and results to establish the back analysis models. In this study, a back analysis method has been developed to estimate geotechnically hard-to-known parameters such as permeability of tunnel filter, underground water table, long-term rock mass load, size of damaged zone associated with seepage and long-term underground motion. The artificial neural network technique is adopted and the numerical models developed in the first part are used to prepare a set of data for learning process. Tunnel behavior, especially the displacements of the lining, has been exclusively investigated for the back analysis.

• Earthquakes and Structures
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• v.24 no.6
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• pp.455-475
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• 2023

The present study investigates the non-linear soil-pile interaction using three-dimensional (3D) non-linear finite element models. The numerical models were validated by using the results of extensive pile load and shaking table tests. The pile performance in liquefiable and non-liquefiable soil has been studied by analyzing the liquefaction ratio, pile lateral displacement (LD), pile bending moment (BM), and frictional resistance (FR) results. The pile models have been developed for the different ground conditions. The study reveals that the results obtained during the pile load test and shaking cycles have good agreement with the predicted pile and soil response. The soil density, peak ground acceleration (PGA), slenderness ratio (L/D), and soil condition (i.e., dry and saturated) are considered during modeling. Four ground motions are used for the non-linear time history analyses. Consequently, design charts are proposed depended on the analysis results to be used for design practice. Eleven models have been used to validate the capability of these charts to capture the soil-pile response under different seismic intensities. The results of the present study demonstrate that L/D ratio slightly affects the lateral displacement when compared with other parameters. Also, it has been observed that the increasing in PGA and decreasing L/D decreases the excess pore water pressure ratio; i.e., increasing PGA from 0.1 g to 0.82 g of loose sand model, decrease the liquefaction ratio by about 50%, and increasing L/D from 15 to 75 of the similar models (under Kobe earthquake), increase this ratio by about 30%. This study reveals that the lateral displacement increases nonlinearly under both dry and saturated conditions as the PGA increases. Similarly, it is observed that the BM increases under both dry and saturated states as the L/D ratio increases. Regarding the acceleration histories, the pile BM was reduced by reducing the acceleration intensity. Hence, the pile BM decreased to about 31% when the applied ground motion switched from Kobe (PGA=0.82 g) to Ali Algharbi (PGA=0.10 g). This study reveals that the soil conditions affect the relationship pattern between the FR and the PGA. Also, this research could be helpful in understanding the threat of earthquakes in different ground characteristics.

• Journal of The Korean Association For Science Education
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• v.27 no.5
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• pp.404-411
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• 2007

The purpose of this study was to examine the types of explanation about different experimental data on students' preconceptions on physical experiment. 45 students were selected from P University by examining their pre-test. The subjects had a scientific conception about a simple pendulum's period of movement, and expected that there was no change in the movement even when the mass of water increased in the can. The students were presented data about pendulum movement inside a can. They recorded this in a blank table and drew a graph about the movement of the pendulum. The responses of students were tested by presenting written anomalous experimental data. Students' recognition, trust about the anomalous data, cognitive conflict, belief change about their preconceptions were examined with written tests also. To measure students' cognitive conflict levels, CCLT (Cognitive Conflict Levels Test) developed in a previous study was used. Some students responded based on preconceptions and regarded the data as manufactured data or experimental error. The students who recognized the anomaly in the situation showed higher cognitive conflict levels than those who didn't recognize the anomaly in the situation. The students who changed their beliefs about preconceptions recognized the data as anomalous situations and showed high cognitive conflict levels than those who didn't abandon their preconceptions. The students who have unchanged beliefs about their preconceptions regarded the data as experimental error.

• Korean Journal of Soil Science and Fertilizer
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• v.21 no.4
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• pp.386-408
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• 1988

A study was conducted to develop a model for estimating evapotranspiration and yield of Chinese cabbages from meteorological factors from 1981 to 1986 in Suweon, Korea. Lysimeters with water table maintained at 50cm depth were used to measure the potential evapotranspiration and the maximum evapotranspiration in situ. The actual evapotranspiration and the yield were measured in the field plots irrigated with different soil moisture regimes of -0.2, -0.5, and -1.0 bars, respectively. The soil water content throughout the profile was monitored by a neutron moisture depth gauge and the soil water potentials were measured using gypsum block and tensiometer. The fresh weight of Chinese cabbages at harvest was measured as yield. The data collected in situ were analyzed to obtain parameters related to modeling. The results were summarized as followings: 1. The 5-year mean of potential evapotranspiration (PET) gradually increased from 2.38 mm/day in early April to 3.98 mm/day in mid-June, and thereafter, decreased to 1.06 mm/day in mid-November. The estimated PET by Penman, Radiation or Blanney-Criddle methods were overestimated in comparison with the measured PET, while those by Pan-evaporation method were underestimated. The correlation between the estimated and the measured PET, however, showed high significance except for July and August by Blanney-Criddle method, which implied that the coefficients should be adjusted to the Korean conditions. 2. The meteorological factors which showed hgih correlation with the measured PET were temperature, vapour pressure deficit, sunshine hours, solar radiation and pan-evaporation. Several multiple regression equations using meteorological factors were formulated to estimate PET. The equation with pan-evaporation (Eo) was the simplest but highly accurate. PET = 0.712 + 0.705Eo 3. The crop coefficient of Chinese cabbages (Kc), the ratio of the maximum evapotranspiration (ETm) to PET, ranged from 0.5 to 0.7 at early growth stage and from 0.9 to 1.2 at mid and late growth stages. The regression equation with respect to the growth progress degree (G), ranging from 0.0 at transplanting day to 1.0 at the harvesting day, were: $$Kc=0.598+0.959G-0.501G^2$$ for spring cabbages $$Kc=0.402+1.887G-1.432G^2$$ for autumn cabbages 4. The soil factor (Kf), the ratio of the actual evapotranspiration to the maximum evapotranspiration, showed 1.0 when the available soil water fraction (f) was higher than a threshold value (fp) and decreased linearly with decreasing f below fp. The relationships were: Kf=1.0 for $$f{\geq}fp$$ Kf=a+bf for f$$I{\leq}Esm$$ Es = Esm for I > Esm 6. The model for estimating actual evapotranspiration (ETa) was based on the water balance neglecting capillary rise as: ETa=PET. Kc. Kf+Es 7. The model for estimating relative yield (Y/Ym) was selected among the regression equations with the measured ETa as: Y/Ym=a+bln(ETa) The coefficients and b were 0.07 and 0.73 for spring Chinese cabbages and 0.37 and 0.66 for autumn Chinese cabbages, respectively. 8. The estimated ETa and Y/Ym were compared with the measured values to verify the model established above. The estimated ETa showed disparities within 0.29mm/day for spring Chinese cabbages and 0.19mm/day for autumn Chinese cabbages. The average deviation of the estimated relative yield were 0.14 and 0.09, respectively. 9. The deviations between the estimated values by the model and the actual values obtained from three cropping field experiments after the completion of the model calibration were within reasonable confidence range. Therefore, this model was validated to be used in practical purpose.