• Journal of Soil and Groundwater Environment
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• v.19 no.1
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• pp.34-45
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• 2014

A variety of physical, chemical, and microbiological techniques have been developed to deal with soil and groundwater contamination. However, in the presence of the large portion of soil micro-environments, contaminant rebound and/or tailing have been frequently reported. Case study of total petroleum hydrocarbons (TPH) removal by full-scale land farming showed that contaminant rebound and/or tailing occurred in 9 out of total 21 cases and subsequently resulted in problems of a long term operation to satisfy TPH guidelines of contaminated soil and groundwater. The main cause of contaminant rebound and tailing is considered to be the strong interactions between contaminants and micro-environments including micro-particles, micro-pores, and organic matter. Thus, this study reviewed the effects of soil micro-environments of soil and groundwater on the removal efficiency for both heavy metals and petroleum contaminants. In addition, the various methods of sampling, analysis, and assessment of soil micro-environments were evaluated. Thorough understanding of the effects of soil micro-environments on contaminant removal will be essential to achieve a cost-effective and efficient solution to contaminated sites.

• Archives of Plastic Surgery
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• v.37 no.4
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• pp.391-395
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• 2010

Purpose: Given that the critical nature of the microvascular anastomosis to what is often a long and difficult reconstructive operation, trainees need to have a high level of microsurgical competence before being allowed to perform microsurgery on patients. Some artificial substitutes and dead or live animal models have been used to improve manual dexterity under the operating microscope. Yet, most surgeons are not equipped with such models, so search for easy available and appropriate microsurgical practice model have been an issue. Umbilical artery, placental vessels and gastroepiploic arteries have been previously suggested as a microsurgical training model, which involves other surgical departments. The purpose of this article is to introduce that saphenous vein specimen obtained from varicose vein surgery is useful and has many advantages as training model for the practice of microvascular anastomosis. Methods: The conventional technique using perforation/inversion method with a metallic stripper is widely performed for varicose vein patients. The stripper is inserted through disconnected safeno-femoral junction and retrieved at the knee or the medial side of ankle. The length of saphenous vein specimens removed is about that of one's leg and inversed from inside out. Obtained saphenous vein specimens are re-inversed and cleansed with normal saline, to be readily available for microsurgical practice. Preserved in a squeezed wet saline gauze and refrigerated, frozen or glycerated specimens were investigated into their comparative quality for microsurgical practice. Results: Varicose vein surgery remains one of the common operations performed in the field of plastic surgery. Convenient informed consent regarding the vessel donation can be easily signed. The diameter of the obtained saphenous vein is as variable as 1.5 to 6 mm, which is already stripped, and is in sufficient length corresponding to that of patient's leg. Vessels specimens were available for microsurgical practice within 1 week period when preserved with squeezed wet saline gauze, and the preservation period could be extended monthly by freezing it. Conclusion: Saphenous vein obtained from varicose vein patients provide with variable size of vessel lumen with sufficient length. The practice can be cost effective and does not require microsurgical laboratory. Additionally there is no need of involving other surgical departments in acquiring vessel specimens. Furthermore, simple preservation method of refrigerating for a week or freezing with squeezed wet saline gauze for a month period, allow the saphenous vein obtained after varicose vein surgery as an excellent model for the microsurgical practice.

• Journal of Korea Water Resources Association
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• v.53 no.8
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• pp.583-595
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• 2020

In this study, using the RCP scenario for Hyoja Drainage subbasin of Cheonggyecheon, we analyzed the change with the Historical and Future rainfall calculated from five GCMs models. As a result of analyzing the average rainfall by each GCMs model, the future rainfall increased by 35.30 to 208.65 mm from the historical rainfall. Future rainfall increased 1.73~16.84% than historical rainfall. In addition, the applicability of LID element technologies such as porous pavement, infiltration trench and green roof was analyzed using the SWMM model. And the applied weight and runoff for each LID element technology are analyzed. As a result of the analysis, although there was a difference for each GCMs model, the runoff increased by 2.58 to 28.78%. However, when single porous pavement and Infiltration trench were applied, Future rainfall decreased by 3.48% and 2.74%, 8.04% and 7.16% in INM-CM4 and MRI-CGCM3 models, respectively. Also, when the two types of LID element technologies were combined, the rainfall decreased by 2.74% and 2.89%, 7.16% and 7.31%, respectively. This is less than or similar to the historical rainfall runoff. As a result of applying the LID elemental technology, it was found that applying a green roof area of about 1/3 of the urban area is the most effective to secure the lag time of runoff. Moreover, when applying the LID method to the old downtown area, it is desirable to consider the priority order in the order of economic cost, maintenance, and cityscape.

• Journal of Korean Society of Transportation
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• v.27 no.5
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• pp.155-162
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• 2009

The recent increase of light rail construction by the private sector in Korea has caused a new issue in forecasting rail demand. Integrated fare systems between several rail operators is convenient and brings cost savings to users, and therefore is also very effective in increasing demand. However, it causes some short-term revenue loss to operators so that the private sector often suggests a non-integrated fare system. The current rail demand forecasting model is based upon an integrated fare system. Thus this model cannot be used to forecast the demand with a non-integrated fare system. Some value of transfer fare should be estimated and applied to forecast the demand in a non-integrated fare system. This study conducted a stated preference (SP) survey on urban railway passengers and estimated the value of transfer fare. The estimated value is 2,609 Won/hr, which is about 52% of in-vehicle time. This shows railway users have a tendency to pay more for transfer fares to save time or distance. This value has some limitations since it is derived from the SP survey. If some non-integrated fare system is applied in the future and a RP survey is conducted and compared with these study results, a more clear value of the transfer fare will be derived.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.08a
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• pp.249-249
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• 2013

Surface-enhanced Raman spectroscopy (SERS) is a sensitive approach to detect and to identify a variety of molecules. To enhance the Raman signal, optimization of the gap between nanostructures is quite important. One-dimensional materials such as nanowires, nanotubes, and nanograsses have great potential to be used in SERS due to their unique sizes and shape dependent characteristics. In this study we investigate a simple way to fabricate SERS substrates based on randomly grown copper oxide (CuO) nanowires. CuO nanograss is fabricated on pre-cleaned Cu foils. Cu oxidized in an ammonium ambient solution of 2.5 M NaOH and 0.1 M $(NH_4)_2S_2O_8$ at $4^{\circ}C$ for 10, 30, and 60 minutes. Then, Cu(OH)2 nanostructures are formed and dried at $180^{\circ}C$ for 2 h. With the drying process, the Cu(OH)2 nanostructure is transformed to CuO nanograss by dehydration reaction. CuO nanograss are grown randomly on Cu foil with the average length of 10 ${\mu}m$ and the average diameter of a 100 nm. CuO nanograsses are covered by Ag with various thicknesses from 10 to 30 nm using a thermal evaporator. Then, we immerse uncoated and Ag coated CuO nanowire samples of various oxidation times in a 0.001M methanol-based 4-mercaptopyridine (4-Mpy) in order to evaluate SERS enhancement. Raman shift and SERS enhancement are measured using a Raman spectrometer (Horiba, LabRAM ARAMIS Spectrometer) with the laser wavelength of 532 nm. Raman scattering is believed to be enhanced by the interaction between CuO nanograss and Ag island film. The gaps between Ag covered CuO nanograsses are diverse from <10 nm at the bottom to ~200 nm at the top of nanograsses. SERS signal are improved where the gaps are minimized to near 10s of nanometers. There are many spots that provide sufficiently narrow gap between the structures on randomly grown CuO nanograss surface. Then we may find optimal enhancement of Raman signal using the mapping data of average results. Fabrication of CuO nanograss based on a solution method is relatively simple and fast so this result can potentially provide a path toward cost effective fabrication of SERS substrate for sensing applications.

• Journal of Preventive Medicine and Public Health
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• v.35 no.4
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• pp.282-286
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• 2002

Objectives : The level of 4-hydroxyproline (4-Hyp) in human urine was measured using high performance liquid chromatography (HPLC) with a fluorescence detector. This method is useful for medical examinations and investigating the radicals induced by physical, chemical, mental stresses. This method is superior to many published several methods in terms of its low cost and ability to analyze many samples. Methods : The urine from workers in a tire manufacturing company (22 male pre- and post-shift workers) and 18 office-workers as controls were analyzed. Data concerning age, the cumulative drinking amount and the cumulative smoking amount was collected with a questionnaire. The optimum applied amount of dansyl-Cl, the optimum reaction temperature and time, the recoveries and the optimum pH of the eluent and buffer were determined.4-Hyp from human urine was derivatized with dansyl-Cl (dimethylamino-naphthalene-1-sulfonyl chloride) after removing the a-amino acid by a treatment with phthalic dicarboxaldehyde (OPA) and cleaned with Bond Elut C18 column. The 4-Hyp derivatives were separated on a reversed phase column by gradient elution with a phosphate buffer (5 mmol, pH 8.0) and acetonitrile, and detected by fluorescence measurements at 340 nm (excitation) and 538 nm (emission). Results : The detection limit for the urinary free 4-Hyp was $0.364{\mu}mol/l$. The recovery rate of 4-Hyp was 99.7%, and the effective pH of the phosphate buffer and borate buffer were 3.0 and 8.0, respectively. From statistical analysis, age, drinking and smoking did not affect the urinary free 4-Hyp in both the controls and workers. The range of urinary 4-Hyp in the controls, pre-shift, and post-shift workers were 0.33-16.44, N.D-49.06, and $0.32-56.27{\mu}mol/l$. From the pared-sample t-test, the urinary 4-Hyp levels in post-shift workers ($11.82{\pm}6.73\;nmmol/mg\;Cre$) were 2-fold higher than in pre-shift workers ($5.36{\pm}5.53\;nmol;/mg\;Cre$) and controls ($4.91{\pm}4.89\;nmol;/mg\;Cre$). Conclusions : This method was developed with high sensitivity, accuracy, and precision. The present method was effectively applied to analyze the urinary free 4-Hyp in both controls and workers.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.38 no.11
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• pp.915-924
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• 2014

In an aero gas-turbine engine, a surface air-oil heat exchanger (SAOHE) is used to cool the oil system for the gearboxes and electric generators. The SAOHE is installed inside the fan casing of the engine in order to dissipate the heat from the oil system into the bypass duct stream. The purpose of this study was to develop an effective numerical method for designing an SAOHE for an aero gas-turbine engine. A two-dimensional model using a porous medium was developed to evaluate the aero-thermal performance of the fins of the heat exchanger, and a one-dimensional flow and thermal network program was developed to save time and cost in the evaluation of the heat exchanger performance. Using this network program, the pressure drop and heat transfer performance of the heat exchanger were predicted, and the results were compared with two-dimensional computational fluid dynamics results and experiment data for validation.

• Journal of Food Hygiene and Safety
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• v.32 no.2
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• pp.83-88
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• 2017

We introduced disposable amperometric immunosensors for the detection of Sildenafil and Vardenafil (SDF/VDF) based on screen printed carbon electrodes. The developed immunosensors were used as a non-competitive sandwich-type enzyme immunoassay with a horseradish peroxidase label. The sensors were constructed on screen printed carbon electrodes by the simple electrochemical deposition of a reduced graphene oxide and chitosan (ErGO-CS) composite. To evaluate the sensing chemistry and optimize the sensor characteristics, a series of electrochemical experiments were carried out including electrochemical impedance spectroscopy, cyclic voltammetry and amperometry. The sensors showed a linear response to SDF/VDF concentrations in a range from 100 pg/mL to 300 ng/mL. The lower detection limit was calculated to be 55 pg/mL, the sensitivity was calculated to be $1.02{\mu}Ang/mL/cm^2$, and the sensor performance exhibited good reproducibility with a relative standard deviation (RSD) of 7.1%. The proposed sensing chemistry strategy and the sensor format can be used as a simple, cost-effective, and feasible method for the in-field analysis of SDF/VDF in functional or health supplement food samples.

• Horticultural Science & Technology
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• v.34 no.1
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• pp.84-93
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• 2016

Plant factories with artificial lights require a large amount of electrical energy for lighting; therefore, enhancement of light use efficiency will decrease the cost of plant production. The objective of this study was to enhance the light use efficiency by using filters to diffuse the light from LED sources in plant factory conditions. The two treatments used diffuse glasses with haze factors of 40% and 80%, and a control without the filter. For each treatment, canopy light distribution was evaluated by a 3-D ray tracing method and canopy photosynthesis was measured with a sealed acrylic chamber. Sixteen lettuces for each treatment were cultivated hydroponically in a plant factory for 28 days after transplanting and their growth was compared. Simulation results showed that the light absorption was concentrated on the upper part of the lettuce canopy in treatments and control. The control showed particularly poor canopy light distribution with hotspots of light intensity; thus the light use efficiency decreased compared to the treatments. Total light absorption was the highest in the control; however, the amount of effective light absorption was higher in treatments than the control, and was highest in treatment using filters with a haze factor of 80%. Canopy photosynthesis and plant growth were significantly higher in all the treatments. In conclusion, application of the diffuse glass filters enhanced the canopy light distribution, photosynthesis, and growth of the plants under LED lighting, resulting in enhanced the light use efficiency in plant factory conditions.

• Journal of KIISE:Information Networking
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• v.33 no.6
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• pp.407-419
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• 2006

As substituting IPv6 network for all IPv4 network in a short time seems unattainable due to high cost and technical limitation, IPv4 and IPv6 are expected to coexist for a certain period of time. Under the co]existing environment of IPv4 and IPv6, interworking brings a number of extra security considerations even if it may have no security problem for each protocol respectively. Thus, the analysis and solutions for those various attacks toward IPv4/IPv6 interworking-related security are inevitably required for the sake of effective transition and settlement to IPv6. In this paper we carried out a proper rule of packet filtering for IPv6-in-IPv4 tunneling interworking environment to protect the IPv4/IPv6 interworking-related security attacks. Design and implementation of the packet filtering system suitable for IPv4/IPv6 tunneling environment in the form of Linux netfilter and ip6tables are also shown. Thru this study, the packet filtering system was found operating correctly ill the tunneling mechanism.