• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.31 no.1D
• /
• pp.65-72
• /
• 2011

When an expressway intersects another expressway, a unique connector needs to be designed between the two consecutive exit ramps. In such a case, it is important to design a connector such that there is enough distance for drivers to find their way safely. A current design manual in Korea prescribes the minimum length of the connector as 240 m. In this research, we have suggested a method for calculating the minimum length of a connector in order to check the feasibility of the currently prescribed length. For this purpose, we have attempted to determine the total perception-reaction time and lane-changing time required by a driver. For determining the driver's perception-reaction time, we have used the driver's decision time in addition to the conventional 2.5 s of perception-reaction time for stopping sight distances. We have considered both the design speed and the average travel speed for the calculation of the length. To evaluate the accuracy of the new method, we have chosen four sites on expressways for which relatively high accident rates were recorded. As a result, we could verify that the current limit (240 m) was sufficient for drivers to be able to change lanes in the given specific geometry. However, the prescribed limit should be revised in case the drivers' decision time is considered to be their perception-reaction time. All new approaches for calculating the ideal length of a connector have been carried out by taking into account the design speed as well as the average travel speed. Owing to the characteristics of the specific geometry for two consecutive exit ramps and the large difference between the design speed and the average travel speed in the objective areas, it is more realistic to use the proposed method by keeping the decision time equal to a driver's perception-reaction time, in order to determine the ideal distance that should be maintained between two consecutive exit ramps.

• Proceedings of KOSOMES biannual meeting
• /
• 2007.11a
• /
• pp.61-67
• /
• 2007

With an entering into force of OPRC-HNS started in June 14th 2007, establishment of response system in a nationwide scale to take care of accidents is required to respond rapidly and effectively. This necessities drove us to analyze national contingency plan for chemicals including national response system against accidents, which is in operation in the US. Main characteristics of the system are well described as an integrated incident command system with a cooperation of responsibilities facilities, manpower, and technical support. In addition, state anψor local authorities tend to have responsibilities on management of disaster with its response activities. Polluters are also charged to pay expenses 3 times expensive provided state or local authorities are conducted. In general, response activities are conducted by private sectors. However, the government will take action with Superfund if the response capacity is over than the polluters can. However, safety are regarded as a primary factor to be considered in the response activities, and try not to recover any pollutants. Personals belonging to USCG and EPA are required to complete specialized courses to promαe professional skills, and are also welcomed to participate in "certification program"

• Journal of the Korean Society of Marine Environment & Safety
• /
• v.24 no.6
• /
• pp.662-669
• /
• 2018

Recently, the installation of submarine power cables is under consideration due to the increase of electric power usage and the development of the offshore wind farm in island areas, including Jeju. In order to protect power cables installed on the seabed, it is necessary to calculate the burial depth based on the characteristics of anchoring, dragging and fishing, etc. However, there is no design standard related to the size of target ships to protect the cables in Korea. In this study, we analyzed the design standards for the protection of domestic submarine pipelines similar to submarine cables, and developed the risk matrix based on the classification by emergency anchoring considering the installation environment, then designed the size of target ships according to the cumulative function scale by ship size sailing through the sea concerned. Also, we linked marine accident conditions, such as anchoring, dragging, etc. and the environmental conditions such as current, sea-area depth of installation etc. to the criteria of the protection of submarine cable, and examined the size of specific target ships by dividing the operating environment of ships into harbor, coastal and short sea. To confirm the adequacy and availability of the size of target ships, we verified this result by applying to No. 3 submarine power cables, which is to be installed in the section from Wando to Jeju Island. This result is expected to influence in the development of a protection system for submarine cables and pipelines as well as the selection of anchor weight according to the determination of burial depth.

• The Journal of The Korea Institute of Intelligent Transport Systems
• /
• v.19 no.4
• /
• pp.45-54
• /
• 2020

This study investigated basic data on walking characteristics, including walking speed and cognitive-response for the elderly, and based on these, the time of walking signal was calculated. The on-site survey examined the actual pedestrian crossing speed using a stopwatch, and the age was divided into groups of ordinary people and the elderly. Analysis of the data showed that the average walking speed for the general public was 1.29 m/s, while the average walking speed for the elderly was 1.13 m/s, higher than that of the general public. In addition, the lower speed of the 15th percentile was analyzed to 1.01 m/s for the general population and 0.85 m/s for the elderly, showing a lower walking speed than the standard for the general area and 0.8 m/s for the protected area. However, for senior citizens who use walking sticks or wheelchairs, the speed of the lower 15th-percentile is 0.73 m/s, which is lower than the current standard of protected areas, according to the analysis.

• Journal of Energy Engineering
• /
• v.25 no.4
• /
• pp.124-132
• /
• 2016

In order to estimate the effect of flow distributors connected to an upper nozzle of CMT(Core Makeup Tank) on the thermal-hydraulic characteristics in the tank, a simplified 2 inch Small Break Loss of Coolant Accident(SBLOCA) was simulated by skipping the decay power and Passive Residual Heat Removal System(PRHRS) actuation. The CMT is a part of safety injection systems in the SMART (System Integrated Modular Advanced Reactor). Each test was performed with reliable boundary conditions. It means that the pressure distribution is provided with repeatable and reproducible behavior during SBLOCA simulations. The maximum flow rates were achieved at around 350 seconds after the initial opening of the isolation valve installed in CMT. After a short period of decreased flow rate, it attained a steady injection flow rate after about 1,250 seconds. This unstable injection period of the CMT coolant is due to the condensation of steam injected into the upper part of CMT. The steady injection flow rate was about 8.4% higher with B-type distributor than that with A-type distributor. The gravity injection during hot condition tests were in good agreement with that during cold condition tests except for the early stages.

• The Journal of Korean Medicine
• /
• v.24 no.2
• /
• pp.66-80
• /
• 2003

Objectives : Recently, herbal acupuncture has been developed in the Korea since the earlier 1960' applied to various diseases including the cerebrovascular accident. The main characteristics of herbal acupuncture are a combination the merit of acupuncture and herbal medicine. It was not well known the therapeutic effect and the mechanism of herbal acupuncture on transient forebrain ischemic injury, although it has been used frequently in clinics. Ramulus Uncariae Cum Uncis (釣鉤藤) has been claimed to possess sedative, anti-spasmodic actions, and treat childhood epilepsy in oriental medical preparation. Also, it has been stated that Ramulus Uncariae Cum Uncis was antioxidatvie effect and neuroprotection against glutamateinduced neuronal death. Methods : In this study, effects of Ramulus Uncariae Cum Uncis' herbal acupuncture on the $GV_{20}{\;}or{\;}LR_3$, named Baek-hue or Tae-chung, on neuroprotection after the transient forebrain ischemia were investigated in Sprague-Dawely rats. Expressions of cFos, FosB and BDNF protein in the hippocampus and cortex were observed at 2 hrs and 48 hrs after transient forebrain ischemia by immunohistochemistry and ELISA technique. Results : Expression of cFos protein was increased slightly in the hippocampus and cortex at 2 hrs after transient forebrain ischemia, but FosB protein was increased highly comparing to cFos protein. However, pretreatment with Ramulus Uncariae Cum Uncis' herbal acupuncture on $GV_{20}{\;}or{\;}LR_3$ significantly increased expression of cFos protein and significantly decreased expression of FosB protein compared to control group, respectively. These features were observed in the motor cortex and retrosplenial granular cortex as well as the hippocampus. Especially, cFos expression was more increased at the herbal acupuncture on $GV_{20}{\;}than{\;}LR_3$, but FosB expression was more decreased in $LR_3$ group than $GV_{20}$ group. Also, pretreatment with Ramulus Uncariae Cum Uncis' herbal acupuncture on $GV_{20}{\;}or{\;}LR_3$ significantly increased the expression of BDNF protein in the hippocampus ($254.88{\pm}12{\;}pg/ml{\;}in{\;}GV_{20}$ group, $245.93{\pm}44.4{\;}pg/ml{\;}in{\;}LR_3$ group) and the cortex ($85.81{\pm}3.45{\;}pg/ml{\;}in{\;}GV_{20}$ group, $111.51{\pm}15.79{\;}pg/ml{\;}in{\;}LR_3$, group) compared to the hippocampus ($134.07{\pm}2.96{\;}pg/ml$) and the cortex ($61.16{\pm}4.11{\;}pg/ml$) in control group at 48 hrs after transient forebrain ischemia. Conclusion : These results suggest that pretreatment with Ramulus Uncariae Cum Uncis' herbal acupuncture on $GV_{20}{\;}or{\;}LR_3$ has neuroprotective effect on transient forebrain ischemia and the herbal acupunture on $GV_{20}{\;}or{\;}LR_3$ may be related to antioxidative effect and calcium channel block of Ramulus Uncariae Cum Uncis. Also, it could be mentioned there is specificity of acupoints treating ischemic injury through the difference between the herbal acupuncture of $GV_{20}{\;}and{\;}LR_3$.

• The Journal of Korean Medicine
• /
• v.24 no.2
• /
• pp.81-93
• /
• 2003

Objectives : Recently, the new therapeutic tool, that is herbal acupuncture, has been developed and applied to various diseases including the cerebrovascular accident. The main characteristics of herbal acupuncture are a combination of acupuncture and herbal medicine. It was not well known the therapeutic effect and the mechanism of herbal acupuncture on transient forebrain ischemic injury, although it has been used frequently in clinics. The objective was to determine the effect of folium artemisiae argyi (艾葉) herbal acupuncture on the trasient forebrain ischemic injured rat. Methods : In this study, the effects of folium artemisiae argyi (艾葉) herbal acupuncture on the $LR_3$ named Taechung, on neuroprotection after the transient forebrain ischemia were investigated in Sprague-Dawely rats. Expressions of cFos, FosB and BDNF protein in the hippocampus and cortex were observed at 2 hrs and 48 hrs after transient forebrain ischemia by immunohistochemistry and ELISA technique. Results : Expression of cFos protein was increased slightly in the hippocampus and cortex at 2 hrs after transient forebrain ischemia, but FosB protein was increased highly comparing to cFos protein. However, pretreatment with folium artemisiae argyi' herbal acupuncture on $LR_3$ significantly increased expression of cFos protein and significantly decreased expression of FosB protein compared to control group. These features were observed in the retrosplenial granular cortex as well as the hippocampus. Also, pretreatment with folium artemisiae argyi' herbal acupuncture on $LR_3$ significantly increased the expression of BDNF protein in the hippocampus ($263.26{\pm}44.56{\;}pg/ml$ extracted by water, $275.35{\pm}51.47{\;}pg/ml$ extracted by moxa tar)and the cortex ($102.33{\pm}13.65{\;}pg/ml$ extracted by water, $109.54{\pm}9.37{\;}pg/ml$ extracted by moxa tar) compared to the hippocampus ($134.07{\pm}2.96{\;}pg/ml$) and the cortex ($61.16{\pm}4.11{\;}pg/ml$) in control group at 48 hrs after transient forebrain ischemia. Conclusions : These results suggest that pretreatment with folium artemisiae argyi' herbal acupuncture on $LR_3$ has neuroprotective effect on transient forebrain ischemia and the herbal acupunture on $LR_3$ may be related to antioxidative function of folium artemisiae argyi.

• Journal of Korean Academy of Nursing
• /
• v.30 no.3
• /
• pp.549-559
• /
• 2000

The purpose of this study was to investigate the correlation between the knowledge and educational needs related to recurrent in coronary artery bypass graft patients as a basis to provide an individual nursing education for the population. The subjects consisted of 110 patients who had coronary artery bypass graft(CABG) at Asan Medical Center in Seoul and Sechong hospital in Buchon. Data was obtained from a knowledge questionnaire and a learning needs questionnaire between November 1998 and February 1999. Data were analyzed using SAS program for Wilcoxon rank sum test and Spearman correlation coefficient. The results were as follows : 1. With regard to the 18 items to measure knowledge, the mean (median) of items 'don't know' was 4.9(4) items. The mean (median) of items answered wrong was 3.2(3) items. The number of items answered 'don't know' tend to show higher in those who had less education, blue color jobs and myocardiac infarction history than in their counter parts. There were higher frequency of items answered 'don't know' in those who had no hypertension 2. With regard to the level of knowledge by questionnaire about CABG, The most "I dont know" (59.1%) highly response was 'He has to be treated with anticoagulant drug to prevent revasculized vessel from obstructing.' The seond highest response (56.4%) was 'If you were hypotensive, the coronary attack would collapse. 'During the hospitalized day, the patient has complete bedrest.' The highest error probability was cholesterol has not to intake.', 'After surgery, the sexual life is need controlled for 1 year. 3. The mean of educational needs was 3.38. With regard to the level of learning needs by sentence about CABG, 'Food that benefit heart disease', 'Recurrence possibility of heart disease', 'Management method of operation site', 'Risk symptom that visit hospital or report immediately' were higher than other sentenses. With regard to the level of learning needs by factor 'food(5 items)', 'disease(9 items)' and 'exercise(3 items)' showed the highest than other factors. The educational needs by patients characteristics tend to show higher in males, under the age of 49, middle or high school degree, previous experience of admission with coronary artery disease, history of myocardial infarction, expierience of PTCA, history of cerebro-vascular accident, previous expierience of smoking than in their counter parts. 4. The number of items answered 'don't know', wrong and correct weren't correlated with the level educational needs. As the results, the number of items answered 'don't know' tend to show higher in those who had less educated, blue color jobs and myocardiac infarction history than in their counter parts. There were higher frequency of items answered 'don't know' in those who had no hypertension .There were higher frequency of items answered 'don't know' on anti-thrombolitic theraphy, hypotension and pain relief. Also there were higher frequency of items answered wrong on bed rest period, cholesterol intake, and sexual life. Educational needs were higher in young age group, had previous experience of procesure and history of other disease. And when we educate CABG patients, education for diet, recurrence possibility of disease, management methods of operation site and risk symptom should be emphasized.

• Transactions of the Korean Society of Mechanical Engineers B
• /
• v.40 no.3
• /
• pp.165-172
• /
• 2016

An experimental study of the thermal-hydraulic characteristics of passive safety systems (PSSs) was conducted using a system-integrated modular advanced reactor-integral test loop (SMART-ITL). The present passive safety injection system for the SMART-ITL consists of one train with the core makeup tank (CMT), the safety injection tank, and the automatic depressurization system. The objective of this study is to investigate the injection effect of the PSS on the small-break loss-of-coolant accident (SBLOCA) scenario for a 0.4 inch line break in the safety-injection system (SIS). The steady-state condition was maintained for 746 seconds before the break. When the major parameters of the target value and test results were compared, most of the thermal-hydraulic parameters agreed closely with each other. The water level of the reactor pressure vessel (RPV) was maintained higher than that of the fuel assembly plate during the transient, for the present CMT and safety injection tank (SIT) flow rate conditions. It can be seen that the capability of an emergency core cooling system is sufficient during the transient with SMART passive SISs.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.21 no.4
• /
• pp.39-48
• /
• 2020

Since the fire accident of ESS (energy storage system) occurred at Gochang KEPCO Power Testing Center in August 2017, 29 fire cases with significant property losses have occurred in Korea. Although the cause of fire accidents have not been identified precisely, it should be considered battery and PCS (power conditioning system) as well as unbalance issues in the distribution system. In particular, circulating currents in a neutral line of a grid-connected transformer, which can affect a magnetized current, may have a negative effect on the ESS with unintentional core saturation and surge voltages at the secondary side of the transformer. Therefore, this paper proposes the modeling of the distribution system, which was composed of a substation, grid-connected transformer, and customer loads using PSCAD/EMTDC S/W, to analyze the phenomena of circulating current and surge voltages of the transformer with unbalanced currents in the distribution system. This paper presents a countermeasure for a circulating current with the installation of NGR (neutral grounding resistor) in grid-connected transformer. From the simulation results, it is clear that exceeding the circulating current and surge voltage at the secondary side of the transformer can be one of the causes of fire accidents.