• Journal of the Korean Geotechnical Society
• /
• 제30권8호
• /
• pp.39-47
• /
• 2014

Frost heaving and thawing settlement cause unexpected stress around buried pipelines, which results in deformation and permanent demage. A large scale laboratory test has been performed to observe deformation, stress, and temperature of a buried pipe during atmospheric temperature changes. From the experimental results, the stress concentrated around the buried pipe is inevitable and deformation is caused by the frost heaving. Even though backfill materials are sandy soils which are normally assumed to be non frost susceptible, it is revealed that frost demage can happen due to drainage condition, the level of ground water table, and water content.

• Maxillofacial Plastic and Reconstructive Surgery
• /
• 제19권3호
• /
• pp.287-299
• /
• 1997

Procurement, cutting, cleansing, freezing, freeze-drying, and demineralization of the allogeneic bone must be made under the germ-free stable condition without bacterial and/or viral contamination. Even thought the bone is procured under the germ free condition, we must have confidence on disinfection of all the solutions that come in contact with tissue during the whole procedure. Lots of antibacterial agents have been introduced for chemical sterilization. Recently ethylene oxide gas sterilization or radiation sterilization is frequently selected as a secendary sterilization procedure. The biological and biochemical response of the graft material differs with the type and concentration of the sterilizing agents, and various toxic reactions have been reported due to the graft material itself and the substance released by the chemicals. The authors conducted the Millipore filter test to observe the toxic effect on L929 fibroblasts according to the effect on activity of succinate dehydrogenase, during the secondary sterilization of the demineralized allogeneic bone powder with irradiation or ethylene oxide gas. The result were as follows : 1. Around the copper disk, positive control group, 10mm diameter discoloration was observed. 2. As same as the negative control group, the disk showed no discoloration. 3. The demineralized allogeneic bone which was sterilized with ethylene oxide gas or irradiation showed no cytotoxicity. 4. From this results, it is suggested that treatment with ethylene oxide gas or irradiation should be effective to sterilize the deminineralized allogeneic bone.

• Journal of the Korea Society of Computer and Information
• /
• 제12권1호
• /
• pp.189-197
• /
• 2007

Developed safety system which transfers danger information to rear cars for accident prevention when drivers detect a accident, a dropping or a freezing during driving on the high way. To prevent an accident, each vehicles mount OBU which is made up of a GPS unit and a transmitter-receiver and the trace of road is always renewed and saved in OBU per a regular past distance. When the driver see dangerous situation, transfer a danger pattern and a trace information by pressing button. All cars which receive information compare the received data with the original data. And then, only cars which are located at the rear in a regular distance respond and occur a warning. Performed a road test at the rate of $30{\sim}50$ kilometer a hour using two test cars which saved about 120meter's space between them were mounted OBU which had 447Mhz transceiver. As a result of the experiment, communication between test cars had no problem. Accordingly, it can use a safety driving device because driver can notice a danger situation and set themselves ready for it using this system in advance.

• The Korean Journal of Pain
• /
• 제35권4호
• /
• pp.468-474
• /
• 2022

Background: The new type of corona virus has a wide range of symptoms. Some people who have COVID-19 can experience long-term effects from their infection, known as post-COVID conditions. The authors aimed to investigate prolonged musculoskeletal pain as a symptom of the post-COVID-19 condition. Methods: This is a descriptive study on the patients who were diagnosed with COVID-19 in a university hospital, between March 2020 and March 2021. Patient records and an extensive questionnaire were used to obtain relevant demographic and clinical characteristics, including hospitalization history, comorbidities, smoking history, duration of the pain, the area of pain, and the presence of accompanying neuropathic symptoms. Results: Of the diagnosed patients, 501 agreed to participate in the study. Among the participants, 318 had musculoskeletal pain during COVID-19 infection, and 69 of them reported prolonged pain symptoms as part of their a post-COVID condition which could not be attributed to any other cause. The mean duration of pain was 4.38 ± 1.73 months, and the mean pain level was 7.2 ± 4.3. Neuropathic pain symptoms such as burning sensation (n = 16, 23.2%), numbness (n = 15, 21.7%), tingling (n = 10, 14.5%), stinging (n = 4, 5.8%), freezing (n = 1, 1.4%) were accompanied in patients with prolonged musculoskeletal pain. Conclusions: Patients with COVID-19 may develop prolonged musculoskeletal pain. In some patients, neuropathic pain accompanies it. Awareness of prolonged post-COVID-19 pain is crucial for its early detection and management.

• Journal of the Korean Geotechnical Society
• /
• 제25권8호
• /
• pp.95-106
• /
• 2009

This study was intended to identify the effect of the wetting on a long-term compression settlement of the rock/soil mixture used as fill material, depending on compaction and grading conditions. The relatively large settlement happened under the fully-submerged condition, and a repeated settlement was monitored when moisture content increased over and over again like the rainfall infiltration. In case of the materials without fine fractions or compacted in wet condition, the settlement caused by wetting was relatively low. In conclusion, the long-term compression settlement of granular (rock/soil mixture) fill material is more affected by the increase of water content and temperature change (freezing and thawing) than creep.

• Food Science of Animal Resources
• /
• 제33권3호
• /
• pp.390-394
• /
• 2013

The aim of this study was to determine the optimal storage condition of pre-packed Hanwoo beef without freezing. Hanwoo loin was purchased from a local distributor at 48 h after slaughter, then sliced in $1.5{\pm}0.5$ cm thickness, and packed in a polyethylene (PE) tray covered with linear low-density polyethylene (LLDPE) film. The studied factors to set the optimal storage condition were chamber temperature (5, 2.5 and $-1^{\circ}C$ for 14 d), cooling method (direct and indirect cooling system), and ultraviolet (UV) light irradiation for beef surface sterilization (0, 30, 60, and 120 min). The changes of pH, thiobarbituric acid reactive substances (TBARS) and number of aerobic bacteria were measured during storage. Beef samples stored in $-1^{\circ}C$ showed the minimal increasing rate in TBARS and microbial growth. After 15 d of storage, there was no significant difference in pH and TBARS values. However, the microbial population of beef stored in direct type cooling chamber ($4.25{\pm}0.66$ Log CFU/g) was significantly lower than that of beef stored in indirect type chamber ($6.47{\pm}0.08$ Log CFU/g) (p<0.05). After 4 d of storage, 60 or 120 min UV light irradiated beef samples showed significantly lower microbial population, and at 14 d of storage, 60 min UV irradiated beef sample showed significantly lower microbial population ($3.14{\pm}0.43$ Log CFU/g) than control ($4.46{\pm}0.13$ Log CFU/g) (p<0.05). However, TBARS values of 60 or 120 min UV light irradiated beef samples were significantly higher than non-irradiated beef sample after 4 d of storage (p<0.05).

• Journal of the Korea Concrete Institute
• /
• 제15권4호
• /
• pp.541-548
• /
• 2003

This study is to investigate the temperature curve and development of compressive strength due to the curing conditions and to evaluate the optimum curing condition of test specimens showing the same development of strength to that of real structures in cold weather. The results of temperature curve with curing conditions in mock-up tests showed the trend of decrease plain concrete with insulation form, plain concrete with heating, concrete with accelerator for freeze protection, and control concrete in turn. The strength development of plain concrete of inside and outside of shelter showed the very slow strength gains due to early freezing, but that of concrete with accelerator for freeze protection showed the gradual increase of strength with time. From this, it is clear that accelerator for freeze protection has the effects of reducing the freezing temperature and accelerating the hardening under low temperature. Strength test results of small specimens embedded in members and located in insulation boxes at the site are similar to that of cores drilled from the members at the same ages, thus it is clear that these curing methods are effective for evaluation in-place concrete strength.

• Korean Journal of Veterinary Research
• /
• 제33권3호
• /
• pp.547-554
• /
• 1993

This study was carried out to investigate the best condition for in vitro and in vivo culture after freezing and thawing of nuclear transplant 2 cell embryos. When nuclear transplant embryos were submitted to electrofusion, the significantly higher fusion rates of 2 cell donor nuclei were achieved at the electric field strength of DC 1.5 kV/cm for 100 and $150{\mu}sec$, DC 2.0 kV/cm for 100 and $150{\mu}sec$ than DC 1.0 kV/cm for 100 and $150{\mu}sec$(p<0.01). The significantly higher fusion rates of 4 cell donor nuclei were achievecl at DC 2.0 kV/cm for 100 and $150{\mu}sec$ than DC 1.0 kV/cm for 100 and $150{\mu}sec$(p<0.01). The fusion rates in 8 cell donor nuclei were 94.2~99.3%. The developmental potency to blastocyst in 2 cell donor nuclei was significantly higher in DC 2.0 kV/cm for $150{\mu}sec$ treated group(p<0.01). The significantly higher developmental potency to blastocyst in 4 cell donor nuclei were achieved at the electric field strength of DC 2.0 kV/cm for $150{\mu}sec$ than DC 1.5 kV/cm for 100 and $150{\mu}sec$, DC 2.0 kV/cm for $100{\mu}sec$ treated group(p<0.01). The develop mental potency to blastocyst in 8 cell donor nuclei was significantly higher in DC 2.0 kV/cm for $100{\mu}sec$ treated group(p<0.01). The developmental potency to blastocyst after nuclear transplantation was significantly higher in 2 cell donor nuclei than in 8 cell donor nuclei(p<0.01). When the recovered embryos in normal morphology were cultured in vitro, there were no significant differences in the developmental potency to blastocyst between the freezing methods and the concentrations of cryoprotectant(p<0.01). The production rates of offspring after transfer of nuclear transplant embryos to recipient mouse were no significant difference in 2, 4 and 8 cell donor nuclei.

• Korean Journal of Animal Reproduction
• /
• 제17권3호
• /
• pp.233-242
• /
• 1993

The effects of in vitro maturation and sperm treatment condition on the in vitro fertilization (IVF) and developmental capacity of bovine oocytes were investigated and the development of embryos was compared under the 2 different co-culture system, with GC or BOEC. The cultured embryo to 16 cell or morula wre transferred into recipients or frozen by 2 different freezing method. The results obtained were summarized as follows; 1. In vitro maturation rates of vovine follicular oocytes cultrued in TCM199 with 10% FCS or ECS were 64.0% and 72.7%, but the case of addition of 10% FCS or ECS to TCM199 co-cultured with granulosa cells were 81.3% and 84.0%, respectively. IVM rate of three TCM199 added to granulosa cells was higher than that of media without granulosa cells. 2. When bovine follicular oocytes were matured in TCM199 with 10% FCS and GC and then fertilized in vitro by sperm treated with caffeine, embryo developments of bovine oocytes co-cultured with BOEC were 38.4% and 51.4%, respectively. But those of bovine oocytes co-cultured with GC were 52.2% by sperm treated with caffeine-heparin. 3. Cleavage rates of bovine oocytes cultured with 10% FCS alone and fertilized in vitro by sperm treated with caffeine-heparin was 33.0%. 4. When bovine follicular oocytes were matured in TCM199 with 10% FCS and GC, embryo developments of bovine ooctyes co-cultured with BOEC of GC were 46.0% and 50.2%, respectively. 5. When bovine follicular oocytes were matured in TCM199 with 10% ECS and GC, embryo developments co-cultured with BOEC or GC were 45.2% and 51.4%, respectively. 6. When Korean Native cow's follicular oocytes matured in TCM199 with 10% FCS and GC, embryo developed co-cultured with BOEC or GC were 45.2% and 51.4%, respectively. 6. When Korean Native cow's follicular oocytes matured in TCM199 with 10% FCS and GC, embryo developments of the bovine oocyte co-cultured with BOEC and GC were 41.8% and 60.1%. But with FCS 10% those of the bovine oocytes co-cultured with BOEC and GC were 42.0% and 48.4%, respectively. 7. When Holstein's follicular oocytes were matured in TCM199 with 10% ECS and GC, embryo developments fo the bovine oocytes co-cultured with BOEC and GC were 50.0% and 57.7%, but with ECS 10% those of the bovine oocytes co-cultured with BOEC and GC were 52.2% and 56.5%, respectively. 8. The viability of frozen-thawed embryos ranged from 60~80% and those of frozen-thawed embryos from vitrification was lower than that from conventional metiod. 9. The selected fresh embryos were transferred nonsurgically to 7 recipients but did not result in pregnancy.

• Journal of the Korean Society of Food Science and Nutrition
• /
• 제12권2호
• /
• pp.62-65
• /
• 1983

As a new practical method for preserving freshness of fish, partially frozen storage has been reported to be useful in terms of K-value, TBA value, sensory evaluation etc. In order to develop a storage procedure to be used in place of cooled or frozen storage for the preservation of precooked fish food, partial freezing for up to two to three weeks was examined using baked mackerel. The criteria for evaluation were made according to the changes in volatile basic nitrogen (VBN), thiobarbituric acid (TBA) value, viable bacterial number, pH, color difference and sensory evaluation in fish muscle. The changes in TBA value of baked muscle during storage at $-3^{\circ}C$ differed slightly from those obserbed during cooled ($5^{\circ}C$) and frozen storage ($-20^{\circ}C$). Partial frozen storage ($-3^{\circ}C$) was effective in prolong an induction period of lipid oxidation during early storage. VBN of baked muscle tends to increase slowly while pH value was decrease during storage and there was no observed significant differences among three different storage condition. Viable bacterial number of the baked mackerel muscle stored at $-3^{\circ}C$ showed significantly less than that stored at $5^{\circ}C$, and similar to that stored at $-20^{\circ}C$ (the levels of $10^2/g$). Judging from the results of sensory evaluation and experimental data, partial frozen storage at $-3^{\circ}C$ seems to be effective as means of short-period preserving baked mackerel.