• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.3
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• pp.585-593
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• 2020

Until now, 29 fire accidents have occurred; 22 of them were caused by the interconnection of renewable energy sources that occurred during the rest period after the lithium-ion battery had been fully charged regardless of the seasons. The fire accidents of ESS were attributed to thermal runaway due to the overcharging of a few cells with the phenomenon of self-energy balancing, which is unintentional current flow from cells with a high SOC to the low cells if the SOC condition of each cell connected in parallel is different. Therefore, this paper proposes a novel configuration and operation algorithm of the BMS to prevent the self-energy balancing of ESS and presents a hybrid SOC estimation algorithm. From the test results of the self-energy balancing phenomenon between aging and normal cells based on the proposed algorithm and BMS, it was confirmed the possibility of self-energy balancing, which is unintentional current flow from cells with a high SOC to cells with a low SOC. In addition, the proposed configuration of the BMS is useful and practical to improve the safety of lithium-ion batteries because the BMS can reliably disconnect a parallel connection of the cells if the self-energy balancing current becomes excessively high.

• Journal of Korean Society of Environmental Engineers
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• v.30 no.10
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• pp.1006-1012
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• 2008

The effect of small and medium scale shipyard operations on environmental pollutions related with civil appeal of nearby residential areas was estimated. PM-10(particles with an aerodynamic diameter less than or equal to 10 $\mu$m) concentrations were higher, as the sampling sites were nearer from shipyards. PM-10 concentrations of sampling sites closer to shipbuilding companies were higher during the normal operation periods than on vacation at which only small works were done. The larger amount of dry deposition was observed as the sampling sites were closer to shipyards. The odor intensity was highly influenced by ambient temperature. Almost all odor intensities measured by air dilution sensory test went over the emission standard in summer. Odor properties measured by instrumental analysis were observed to exceed the emission standard enforced to the shipyards. Odor compounds such as ammonia, sulfur compounds and trimethylamine went over the standard. Concentrations of styrene and aldehydes were lower than the olfactory threshold. All equivalent sound levels measured at daytime except the value of SP-3 pont were in excess of the environmental standard. Almost all sound levels at nighttime in all measuring sites were higher than the environmental standard. The results of this study shows counterplans need to be established for reducing the civil appeal related pollutions in the research areas.

• Journal of Chest Surgery
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• v.21 no.2
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• pp.211-222
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• 1988

Tetralogy of Fallot is a cyanotic congenital heart disease characterized by large ventricular septal defect[VSD] and stenosis of right ventricular outflow tract[RVOT] and the degree of RVOT stenosis and the state of pulmonary arteries are the major determinant of prognosis of this anomaly after operation. The sum of blood flow through RVOT and collateral flow from systemic arteries determine the total pulmonary blood flow and it is drained to left atrium and left ventricle. Therefore the degree of development of left ventricle not only reflects pulmonary blood flow and the status of peripheral pulmonary arteries but also affects postoperative prognosis as a systemic ventricle. In this article, left ventricular volume and its influence on postoperative cardiac function in tetralogy of Fallot were studied in 34 patients operated on at Department of Thoracic and Cardiovascular Surgery, Seoul National University Hospital in 1985. Mean age of the patients was 5 1/12*3 9/12 years[range 9/12 - 14 8/12 years], mean body surface area[BSA] 0.65*0.20m2[range 0.38 - 1.22m2], mean body weight 15.6k6.48kg[range 7.0 - 36kg]and mean hematocrit 50.6*9.77%[range 32.0 - 73.5%]. Left ventricular end-diastolic volume[LVEDV] of them were from 11.2 to 113cc and there was a good linear correlation between BSA[m2, X]and LVEDV[cc, Y][Y= - 20.0+923x, r= 0.84, p < 0.005]. Mean LVEDV/m2 was [57.6 * 18.3 cc / m2[range 28.7 - 95.8 cc / m2] and there was a significant reduction of volume compared with normal value. As body surface increases, there was a increasing tendency in LVEDV/m2 but there was no statistical significance. Mean total amount of postoperatively infused dopamine in these 33 patients[except one who expired postoperatively] was 65.6*74.5mg / kg and it was 40.6*44.0mg / kg in routine RVOT widening group [Group I] and 205*49.3mg / kg in transannular RVOT widening group[Group II]. There was a statistically significant difference between two groups. In group I patients there was a good linear inverse correlation between dopamine total amount[mg / kg, Y] and LV volume[cc / m2, X] [Y = 150 - 1.89 X, r = - 0. 77, p < 0.005]. But there were no correlations between dopamine total amount and Hct, cardiopulmonary bypass time and aorta cross clamp time. In conclusion, the patient with small preoperative left ventricular volume required more amount of dopamine as an inotropic agent for the maintenance of a cardiac function in postoperative period. But this is a result of immediate postoperative period and does not reflect the long term effect of left ventricular volume in tetralogy of Fallot. There must be more study for the evaluation of its long term effect.

• Journal of Chest Surgery
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• v.35 no.2
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• pp.144-148
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• 2002

The present study was done to determine the efficacy and safety of varicose vein removal using a minimally invasive, powered vein-extracting device with cutaneous transillumination and tumescent anesthesia techniques and then compared this to a retrospective group of conventional phlebectomy operations. There were 133 limbs in 104 patients(72 women, 32 men) treated with the use of the vein extractor aided by transcutaneous illumination. The hydrodissection was performed with Trivex™ Irrigated illuminator(Smith & Nephe $w^{ R}$) system using normal saline after the 2~3mm sized skin incision. Varicose clusters were extracted by the use of TriveTM esector(Smith & Nephe $w^{ R}$) system under transillumination. After the varisoce vein extraction, the operation area was compressed with surgical pad for bleeding control. The complication rate was 3.84% The mean number of incisions was 3.24 and mean operative time per limb was 65.9 minutes. The mean hospitalization was 1.86 days. The varicose vein extraction using transilluminated powered phlebectomy(TIPP) is a safe, efficacious and cosmetically satisfactory method. The procedure decreases the operating time and the number of incisions required to remove varicose clusters. Further evaluation and long term follow up will be necessary to determine the recurrence rate and long termcomplications.to determine the recurrence rate and long termcomplications.

• Journal of the Korean Vacuum Society
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• v.21 no.6
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• pp.301-311
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• 2012

Discharge property of plasma jet devices is investigated for the application to the doping processes of crystalline solar cells and others. Current-voltage characteristics are shown as the typical normal-glow discharge in the various gas pressure of plasma jets, such as in the atmospheric plasma jets of Ar-discharge, in the ambient pressure of atmospheric discharge, and in the ambient Ar-pressure of Ar-discharge. The discharge voltage of atmospheric plasma jet is required as low as about 2.5 kV while the operation voltage of low pressure below 200 Torr is low as about 1 kV in the discharge of atmospheric and Ar plasma jets. With a single channel plasma jet, the irradiated plasma current on the doped silicon wafer is obtained high as the range of 10~50 mA. The temperature increasement of wafer is normally about $200^{\circ}C$. In the result of silicon wafers doped by phosphoric acid with irradiating the plasma jets, the doping profiles of phosphorus atoms shows the possibility of plasma jet doping on solar cells.

• Korean Journal of Head & Neck Oncology
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• v.21 no.2
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• pp.146-150
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• 2005

Background and Objectives: When the pleomorphic adenoma(PA) recures, the tumor tends to become a multinodular mass that infiltrates into the normal tissue which is not a common condition for a benign tumor. This manifestation is probably due to the difference in cell biology of the recurrent tumor compared to that of the primary PA. The aim of this study is to assay the immunhistochemical characteristics of the recurrent PA compared to the primary PA and to evaluate whether this property can be used for developing a method that can select the patients who have higher risk to recur. Materials and Methods: Thirteen patients were enrolled in the primary PA group and 15 patients who had a recurrent PA were enrolled in the recurrent PA group. To evaluate the cell biology of the tumor, immunohistochemical stainings of Ki-67, bcl-2 and p53 were performed. Results: There was no difference in the expression of Ki-67 (p=0.117, p=.208) and p53 (p=.430, p=.328). The extent stained by bcl-2 was significantly larger in the recurrent PA group (p=.033, p=.014). The expression of bcl-2 did not increase while time passed. Conclusion: The high expression of bcl-2 seems to be a property of the recurrent PA group which can be found even during first operation before recurrence. By this immunhistochemical characteristic, we would be able to sort out the patients who have higher risk to recur.

• Fire Science and Engineering
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• v.30 no.4
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• pp.111-120
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• 2016

This is an experimental study to analyze the explosion and fire hazards of mobile phone batteries. Using the lithium-ion batteries currently used on smart phone as the experiment samples, the experiments were conducted by overcharging, internal and external short circuit, and thermal shock with the potential of explosion and fire caused by careless use or abnormal conditions. The experiment results showed that, in the case of overcharging and external short circuit, there was no explosion and fire hazard in the normal operation of the protection circuit module (PCM), but there were big risks when the PCM faulted conditions were assumed. In the case of the experiments by internal short circuit and thermal shock, such risks varied depending on a battery charge state. In other words, it could be verified that there were low risks of explosion and fire in a full discharge state, but there were high risks in a full charge state. These experiment results suggest that to minimize the explosion and fire hazards of mobile phone batteries, an alarm device is necessary when the PCM fault occurs. In addition, a solid battery case should be made and safety equipment, such as a cooling device to avoid high temperature, is needed.

• Korean Journal of Pharmacognosy
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• v.47 no.3
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• pp.264-272
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• 2016

This study was carried out to evaluate the preventive effect of the Corni Fructus (SSU) 50 % EtOH extract (SSU-E50) against bisphenol A (BPA) toxicity in Leydig cells and improving testosterone deficiency syndrome in orchidectomized Sprague-Dawly (SD) rats. Antioxidant properties were measured by radical scavenging activity of SSU-E50 in ABTS assay and DPPH assay. Also, real-time polymerase chain reaction(real-time PCR) was performed to quantify the mRNA expression levels of antioxidant enzyme. SD rats were divided into eight group: normal, sham operation (Sham), orchidectomized (ORX), ORX treated with testosterone 1 mg/kg (Tes. 1), ORX treated with SSU water extract 100 mg/kg (SSU-A 100) and 300 mg/kg (SSU-A 300), ORX treated with SSU 50 % EtOH extract 100 mg/kg (SSU-E 100) and 300 mg/kg (SSU-E 300). On a comparative basis, the SSU showed better activity quenching ABTS with an IC50 value of 0.29 mg/ml and DPPH with an IC50 value of 0.33 mg/ml. Cell viability was evaluated by MTS assay as described not cytotoxic at the highest concentration of $500{\mu}g/ml$. Cytotoxicity of BPA showed in $200{\mu}M$, but definitely survived by treatment with SSU in Leydig cells. In addition, SSU increased the mRNA expression levels of antioxidant enzyme in BPA induced Leydig cells. Superoxide dismutase (SOD) level was slightly increased and malondialdehyde (MDA) level was decreased with SSU-A 100 in in-vivo. These results suggest that Corni Fructus extracts have the greatest property as a natural anti-oxidative and improves testosterone deficiency syndrome source.

• International Journal of Highway Engineering
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• v.8 no.4 s.30
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• pp.125-133
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• 2006

In this study, the Korean Industrial Standard(KS) penetration grade system was examined to evaluate its statistical validity. It was found from this limited study that the system has no gap between each grade, the binder falling out of limit trespasses into other binder grade. Therefore, many products can have similar property level with an adjacent grade even though the mean value is within the specification limit. It was also found out that the equal range setup of each grade, such as 20 for 40-60, 60-80, 80-100, has no statistical foundation. Since KS penetration grade is defined without gap between each grade, the producer must maintain the coefficient of variation below the level by the ASTM system to satisfy the normal quality control limit of products. Due to its lack of a gap between grades, higher percentage of products will be duplicated even if the mean is at the median of the specification limits due to material's quality uncertainty. Especially if the mean moves toward the upper limit, a half or more of the binder grade will be overlapped with the upper binder grade. Therefore, KS penetration specification should be immediately modified by statistically valid methodologies.

• Tunnel and Underground Space
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• v.28 no.1
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• pp.38-58
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• 2018

The ventilation system plays a crucial role in underground mine safety. The main objective of the ventilation system is to supply sufficient air to dilute the contaminated air at working places and consequently provide tenable environment during the normal operation, while it also should be capable of controlling the fire propagation and facilitate rescue conditions in case of fire in mines. In this study, a smoke control fan was developed for the auxiliary ventilation as well as the fire smoke exhaust. It works as a free-standing auxiliary fan without tubing to dilute or exhaust the contaminated air from the working places. At the same time, it can be employed to extract the fire smoke. This paper aims to examine the smoke control efficiency of the fan when combined with the current ventilation system in mines. A series of the site experiments and numerical simulations were made to evaluate the fan performance in blind entry development sites. The tracer gas method with SF6 was applied to investigate the contaminant behavior at the study sites. The results of the site study at a large-opening limestone mine were compared with the CFD analysis results with respect to the airflow pattern and the gas concentration. This study shows that in blind development entry, the most polluted and risky place, the smoke fan can exhaust toxic gases or fire smoke effectively if it is properly combined with an additional common auxiliary fan. The venturi effect for smoke exhaust from the blind entry was also observed by the numerical analysis. The overall smoke control efficiency was found to be dependent on the fan location and operating method.