• Journal of Environmental Health Sciences
• /
• v.39 no.1
• /
• pp.83-89
• /
• 2013

Objectives: The purpose of this experiment was to illuminate the relationship between the phosphorus removal rate of unit operation and the phosphorus removal rate of phosphorus volume loading in the Ferrous Nutrient Removal process, which consists of an anoxic basin, oxic basin, and iron precipitation apparatus. Methods: This study was conducted in order to improve the effect of nitrogen and phosphorus removal in domestic wastewater using the FNR (Ferrous Nutrient Removal) process which features an iron precipitation reactor in anoxic and oxic basins. The average concentration of TN and TP was analyzed in a pilot plant ($50m^3/day$). Results: The removal rate of T-N and T-P were 66.5% and 92.8%, respectively. The $NH_3-N$ concentration of effluent was 2.62 mg/l with nitrification in the oxic basin even though the influent was 17.7 mg/l. The $NO_3$-N concentration of effluent was 5.83 mg/l through nitrification in oxic basin even though the influent and anoxic basin were 0.82 mg/l and 1.00 mg/l, respectively. The specific nitrification of the oxic basin ($mg.NH_3$-Nremoved/gMLVSSd) was 16.5 and specific de-nitrification ($mg.NO_3$-Nremoved/gMLVSSd) was 90.8. The T-P removal rate was higher in the oxic basin as T-P of influent was consumed at a rate of 56.3% in the anoxic basin but at 90.3% in the oxic basin. The TP removal rate (mg.TP/g.MLSS.d) ranged from 2.01 to 4.67 (3.06) as the volume loading of T-P was increased, Conclusions: The test results showed that the electrolysis of iron is an effective method of phosphorus removal. Regardless of the temperature and organic matter content of the influent, the quality of phosphorus in the treated water was both relatively stable and high due to the high removal efficiency. Nitrogen removal efficiency was 66.5% because organic matter from the influent serves as a carbon source in the anoxic basin.

• Journal of Korean Society of Transportation
• /
• v.22 no.6
• /
• pp.47-54
• /
• 2004

Recently, a large reduction in domestic aviation demand had roughly shown in the range between 34% and 75% in east central and western corridor of Korea. The reasons for the drop in air traffic demand were the provisioning of several new highway serveces and the national economic difficulties. Since April 2004, moreover, the Korea Train Express(KTX) was operated between Seoul and Daegu in the first phrase of 293Km in KTX operational distance and 258Km in air route distance. The operation of KTX significantly impacted air traffic volume, particularly on the overlapped air routes with KTX routes. This study analyzed the effects on air traffic demand in accordance with the opening of KTX by applying the Stated Preference (SP) survey method, the survey conducted prior to 8 months of the KTX initiative. Also, the comparison of the decreased demand forecast by SP analysis and actual revealed traffic volume during two months service after inauguration of KTX was conducted. The Seoul-Daegu route was analysed using the 3 variables considered access and egress time, fare rate, operational frequency. The result obtained from the analysis showed that air users would be preferred only 14%. Comparatively, however, the actual revealed air passengers after the opening KTX were remained 28%, The less "decreased demand" was caused by the instability of the KTX's operation in the initial stage. Therefore, small numbers of passenger were preferable to airservices rather than high speed railroad service.

• Journal of the Korean Society of Manufacturing Process Engineers
• /
• v.15 no.3
• /
• pp.130-134
• /
• 2016

Due to the need for advanced technologies in the automotive industry, the demand for lighter and safer vehicles has increased. Even though various nonferrous metals, like Aluminum, Magnesium and also Carbon Fiber Reinforced Plastic (CFRP), have been implemented in the automotive industry, a lot of technical research and development is still focused on ferrous metals. In particular, the market volume of High Strength Steel (HSS) parts and Ultra High Strength Steel (UHSS) by hot press forming parts has expanded significantly in all countries' automotive industries. A new tool steel, High Thermal-Conductivity Tool Steel (HTCS), for stamping punches and dies has been developed and introduced by Rovalma Company (Spain), and it is able to support better productivity and quality during hot press forming. The HTCS punches and dies could help to reduce cycle time due to their high thermal conductivity, one of the major factors in hot press forming operation. In this study, test dies were manufactured in order to verify the high thermal conductivity of HTCS material compared to SKD6. In addition, thermal deformation was inspected after the heating and cooling process of hot press forming. After heating and cooling, the test dies were measured by a 3D scanner and compared with the original geometry. The results showed that the thermal deformation and distortion were very small even though the cooling time was reduced by 2 seconds.

• Proceedings of the Materials Research Society of Korea Conference
• /
• 2012.05a
• /
• pp.73-73
• /
• 2012

Modern technology-driven society largely relies on hybrid electric vehicles or electric vehicles for eco-friendly transportation and the use of high technology devices. Lithium rechargeable batteries are the most promising power sources because of its high energy density but still have a challenge. Graphite is the most widely used anode material in the field of lithium rechargeable batteries due to its many advantages such as good cyclic performances, and high charge/discharge efficiency in the initial cycle. However, it has an important safety issue associated with the dendritic lithium growth on the anode surface at high charging current because the conventional graphite approaches almost 0 V vs $Li/Li^+$ at the end of lithium insertion. Therefore, a fundamental solution is to use an electrochemical redox couple with higher equilibrium potentials, which suppresses lithium metal formation on the anode surface. Among the candidates, $Li_4Ti_5O_{12}$ is a very interesting intercalation compound with safe operation, high rate capability, no volume change, and excellent cycleability. But the insulating character of $Li_4Ti_5O_{12}$ has raised concerns about its electrochemical performance. The initial insulating character associated with Ti4+ in $Li_4Ti_5O_{12}$ limits the electronic transfer between particles and to the external circuit, thereby worsening its high rate performance. In order to overcome these weak points, several alternative synthetic methods are highly required. Hence, in this presentation, novel ways using a synergetic strategy based on 1D architecture and surface coating will be introduced to enhance the kinetic property of Ti-based electrode. In addition, first-principle calculation will prove its significance to design Ti-based electrode for the most optimized electrochemical performance.

• Korean Journal of Remote Sensing
• /
• v.39 no.5_4
• /
• pp.1173-1183
• /
• 2023

Over the past 20 years, Korea's overall import and export cargo volume has increased at an average annual rate of approximately 5.3%. About 99% of the cargo is still being transported by sea. Due to recent increases in maritime cargo volume, congestion in maritime logistics has become challenging due to factors such as the COVID-19 pandemic and conflicts. Continuous monitoring of ports has become crucial. Various ground observation systems and Automatic Identification System (AIS) data have been utilized for monitoring ports and conducting numerous preliminary studies for the efficient operation of container terminals and cargo volume prediction. However, small and developing countries' ports face difficulties in monitoring due to environmental issues and aging infrastructure compared to large ports. Recently, with the increasing utility of artificial satellites, preliminary studies have been conducted using satellite imagery for continuous maritime cargo data collection and establishing ocean monitoring systems in vast and hard-to-reach areas. This study aims to visually detect ships docked at berths in the Busan New Port using high-resolution satellite imagery and quantitatively evaluate berth utilization rates. By utilizing high-resolution satellite imagery from Compact Advanced Satellite 500-1 (CAS500-1), Korea Multi-Purpose satellite-3 (KOMPSAT-3), PlanetScope, and Sentinel-2A, ships docked within the port berths were visually detected. The berth utilization rate was calculated using the total number of ships that could be docked at the berths. The results showed variations in berth utilization rates on June 2, 2022, with values of 0.67, 0.7, and 0.59, indicating fluctuations based on the time of satellite image capture. On June 3, 2022, the value remained at 0.7, signifying a consistent berth utilization rate despite changes in ship types. A higher berth utilization rate indicates active operations at the berth. This information can assist in basic planning for new ship operation schedules, as congested berths can lead to longer waiting times for ships in anchorages, potentially resulting in increased freight rates. The duration of operations at berths can vary from several hours to several days. The results of calculating changes in ships at berths based on differences in satellite image capture times, even with a time difference of 4 minutes and 49 seconds, demonstrated variations in ship presence. With short observation intervals and the utilization of high-resolution satellite imagery, continuous monitoring within ports can be achieved. Additionally, utilizing satellite imagery to monitor changes in ships at berths in minute increments could prove useful for small and developing country ports where harbor management is not well-established, offering valuable insights and solutions.

• Journal of Yeungnam Medical Science
• /
• v.8 no.2
• /
• pp.128-137
• /
• 1991

Peritoneal dialysis has been widely considered to be the dialytic treatment of choice for acute renal failure in infants and young children, because the technique is simple, safe and easily adapted for these patients. Also peritoneal dialysis in infants might have more effective ultrafiltration and clearance than in adults. In certain circumstances associated with hemodynamic instability, ordinary volume peritoneal dialysis(30-50 ml/kg body weight per exchange) or hemodialysis may not be suitable unfortunately. But frequent cycled, low volume, high concentration peritoneal dialysis may be more available to manage the hemodynamically untable acute renal failure of newborns and infants. Seven infants underwent peritoneal dialysis for hemodynamically unstable acute renal failure with low exchange volume($14.2{\pm}4.2ml/kg$), short exchange time(30 to 45 minutes) and hypertonic glucose solution(4.25% dextrose). Age was $1.9{\pm}1.3$ months and body weight was $4.6{\pm}1.6kg $. Etiology of acute renal failure was secondary to sepsis with or without shock(5 cases) and postcardiac operation(2 cases). Catheter was inserted percutaneously with pigtail catheter or Tenkhoff catheter by Seldinger method. Dialysate was commercially obtained Peritosol which contained sodium, chloride, potassium, magnesium, lactate and calcium. Net ultrafiltration(ml/min) showed no difference between low volume dialysis and control($0.27{\pm}0.09$ versus $0.29{\pm}0.09$) Blood BUN decreased from $95.7{\pm}37.5$ to $75.7{\pm}25.9mg/dl$ and blood pH increased from $7.122{\pm}0.048$ to $7.326{\pm}0.063$ after 24 hours of peritoneal dialysis. We experienced hyperglycemia which were controlled by insulin(2 episodes), leakage at the exit site(2), mild hyponatremia(1) and Escherichia coli peritonitis(1). Two children of low volume dialysis died despite the treatment. In our experience, low volume and high concentration peritoneal dialysis with frequent exchange may have sufficient ultrafiltration and clearance without significant complications in the certain risked acute renal failure of infants.

• The Transactions of the Korean Institute of Power Electronics
• /
• v.16 no.2
• /
• pp.114-121
• /
• 2011

This paper proposes a soft-switching interleaved boost converter which is suitable for high step-up and high power applications. Compared to the conventional boost converter the proposed converter can achieve approximately doubled voltage gain using the same duty cycle. The voltage ratings of the switch and diode are reduced to half, which result in the use of devices with lower $R_{DS(ON)}$ and on drop leading to reduced conduction losses. Also, voltage ratings of the passive components are reduced, and therefore the total energy volume is reduced to half. Further, the switch is turned on with ZVS in the CCM operation, and the diode is turned off with ZCS which results in negligible surge caused by diode reverse recovery leading to reduced switching losses. The validity of the proposed converter is proved through a 2kW prototype.

• Journal of Environmental Health Sciences
• /
• v.36 no.4
• /
• pp.323-336
• /
• 2010

We evaluated the properties of a fixed-bed column reactor for high-concentration tetrachloroethylene (PCE) removal. The anaerobic bacterium Clostridium bifermentans DPH-1 was able to dechlorinate PCE to cis-1,2-dichloroethylene (cDCE) via trichloroethylene (TCE) at high rates in the monoculture biofilm of an upflow fixed-bed column reactor. The first-order reaction rate of C. bifermentans DPH-1 was relatively high at $0.006\;mg\;protein^{-1}{\cdot}l{\cdot}h^{-1}$, and comparable to rates obtained by others. When we gradually raised the influent PCE concentration from $30\;{\mu}M$ to $905\;{\mu}M$, the degree of PCE dechlorination rose to over 99% during the operation period of 2,000 h. In order to maintain efficiency of transformation of PCE in this reactor system, more than 6 h hydraulic retention time (HRT) is required. The maximum volumetric dechlorination rate of PCE was determined to be $1,100\;{\mu}mol{\cdot}d^{-1}l$ of reactor $volume^{-1}$, which is relatively high compared to rates reported previously. The results of this study indicate that the PCE removal performance of this fixed-bed reactor immobilized mono-culture is comparable to that of a fixed-bed reactor mixture culture system. Furthermore, our system has the major advantage of a rapid (5 days) start-up time for the reactor. The flow characteristics of this reactor are intermediate between those of the plug-flow and complete-mix systems. Biotransformation of PCE into innocuous compounds is desirable; however, unfortunately cDCE, which is itself toxic, was the main product of PCE dechlorination in this reactor system. In order to establish a system for complete detoxification of PCE, co-immobilization of C. bifermentans DPH-1 with other bacteria that degrade cDCE aerobically or anaerobically to ethene or ethane may be effective.

• Journal of the Korean Society of Food Science and Nutrition
• /
• v.44 no.4
• /
• pp.506-515
• /
• 2015

In this study, the effect of Goheung pomegranate extract on postmenopausal syndrome was evaluated both in vitro and in vivo in ovariectomized Sprague-Dawly (SD) rats. Sixty female SD rats were divided into six groups: sham, sham operation and distilled water; OVX, ovariectomized and distilled water; PE1, ovariectomized and pomegranate concentrate (0.75 mL/twice/d); PE2, ovariectomized and pomegranate concentrate (1.5 mL/twice/d); PE3, ovariectomized and pomegranate concentrate (2.2 mL/twice/d); and CE, ovariectomized and commercial pomegranate concentrate (2.2 mL/twice/d). Percent bone volume (bone volume/tissue volume) and trabecular thickness (Tb.Th) improved in a dose-independent manner in PE1, 2, and 3. Especially, bone mineral density was significantly improved in PE3 (P<0.05) compared to OVX. Pomegranate extract reduced body weight and visceral fat mass. High density lipoprotein cholesterol (HDL-C) level slightly increased in a dose-independent manner in the experimental group. In addition, HDL-C/total cholesterol level of PE3 significantly increased (P<0.05) compared with OVX. These results show that pomegranate concentrate improved blood lipid levels and bone metabolism in ovariectomized rats. Therefore, Goheung pomegranate concentrates are expected to improve cardiovascular and bone-related diseases in menopausal women.

• Journal of the Korean Society of Marine Environment & Safety
• /
• v.26 no.1
• /
• pp.31-38
• /
• 2020

The characteristics of ship traffic routes and the long term fluctuation in marine traf ic volume of the incoming and outgoing routes of the Yeosu Gwangyang Port were analyzed using vessel traffic data from the past 22 years and a real-time vessel traffic volume survey performed for 72 hours per year, for three years, between 2015 and 2017. As of 2017, the number of vessels passing through Yeosu Gwangyang Port was about 66,000 and the total tonnage of these ships was about 804,564 thousand tons, which is a 400 % increase from the 189,906 thousand tons shipped in 1996. Specifically, the dangerous cargo volume was 140,000 thousand tons, which is a 250 % increase compared to 1996. According to the real-time vessel traffic volume survey, the average daily number of vessels was 357, and traf ic route utilization rates were 28.1 % in the Nakpo sea area, 43.8 % in the specified sea area, and the coastal area traf ic route, Dolsan coastal area, and Kumhodo sea area showed the same rate of 6.8 %. Many routes meet in the Nakpo sea area and, parallel and cross passing were frequent. Many small work vessels entered the specific sea area from the neighboring coastal area traffic route and frequently intersected the path of larger vessels. The anchorage waiting rate for cargo ships was about 24 %, and the nightly passing rate for dangerous cargo ships such as chemical vessels and tankers was about 20 %. Although the vessel traffic volume of Yeosu Gwangyang Port increases every year, the vessel traffic routes remain the same. Therefore, the risk of accidents is constantly increasing. The route conditions must be improved by dredging and expanding the available routes to reduce the high risk of ship accidents due to overlapping routes, by removing reefs, and by reinforcing navigational aids. In addition, the entry and exit time for dangerous cargo ships at high-risk ports must be strictly regulated. Advancements in the VTS system can help to actively manage the traffic of small vessels using the coastal area traffic route.