• Proceedings of the Korean Society for Agricultural Machinery Conference
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• 1993.10a
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• pp.584-590
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• 1993

The constructed closed recycling system discussed in this technical report will be economically viable in future for the production of fish and vegetable in earth, space station and space colony, further, it will contribute a lot in the prevention of pollution in the world's ecological system. To make combined system, water management (Nitrification) is required, and it took 45 days to breed microorganism which facilitates this process. After this period , the recycle was confirmed to be working .Using derived equations, the expected nutrient characteristics of waste water were determined and it was found that the resulting nutrient balance was almost same as that in hydroponic solution when KOH was added to maintain pH level. Reverse osmosis (RO) system could solve the problem of the low nutrient concentration . It was found that plants grow well in fish waste water which was produced using RO system. RO system could combine fish and plant production through the advantageous use of separated high concentration water for plant and permeated water for fish in integrated combined system.

• Journal of Advanced Navigation Technology
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• v.4 no.1
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• pp.67-77
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• 2000

This paper proposes a reduction scheme for codebook search time in the adaptive codebook using wavelet transformed coefficients. In a CELP coder, pitch estimation with a combined open loop and closed loop search in adaptive codebook needs a lengthy search. More precisely, the pitch search using autocorrelation function over all possible ranges has been shown inefficient compared to the consuming time. In this paper, we propose a new adaptive codebook search algorithm which ensures the same position for the pitch with maximum wavelet coefficient over various scaling factors in Dyadic wavelet transform. A new adaptive codebook search algorithm reduces 25% conventional search time with almost the same quality of speech.

• Proceedings of the KIEE Conference
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• 1995.11a
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• pp.46-48
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• 1995

An efficient technique for the analysis of a general class of microstrip structures with a substrate is applied in this paper using newly-derived closed-form spatial domain Green's functions employed in conjunction with the Method of Moments(MoM). The computed current distributions on the microstrip structures are used to determine the scattering parameters of microstrip discontinuties and the input impedances of microstrip patch antennas. It is shown that the use of the closed-form Green's functions in the context of the MoM provides a computational advantage in terms of the CPU time by almost two orders of magnitude over the conventional spectral domain approach employing the transformed version of the Green's functions.

• Journal of Environmental Impact Assessment
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• v.13 no.3
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• pp.115-124
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• 2004

To utilize a closed municipal solid waste landfill site in environmentally secure conditions, it is necessary to verify the stabilization level of landfill leachate. To assess leachate stabilization of an open-dumping municipal solid waste landfill (Noeun Landfill) which is located at the upper drainage basin of Namhan River which flows into Lake Paldang utilized for Seoul Metropolitan water supplies, the surrounding characteristics of the landfill site was surveyed. After then, leachate, groundwater and soil samples from this landfill were chemically analyzed, and the analysis results were evaluated by "The Criteria of Landfill Waste Stabilization(CLWS)", "Discharge Criteria of Landfill Leachate", "The Criteria of Domestic Use in Groundwater Quality", and "Soil Contamination Criteria" promulgated by Korean Ministry of Environment. The closed open-dumping landfill was equipped with the final soil cover, 3 groundwater monitoring wells and poor landfill gas extraction devices for the post-closure management of the landfill. BOD/CODcr ratios in leachate were less than or slightly higher than 1/10. This results seemed to imply that the leachate stabilization level of this landfill based on the CLWS was almost completed. Qualities of groundwater sampled from monitoring wells located at outside of landfill were adequate for "The Criteria of Domestic Use in Groundwater Quality". Finally, concentrations of soil contaminants that were likely to be influenced by this landfill site were adequate to "Soil Contamination Criteria".

• Korean Journal of Human Ecology
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• v.3 no.2
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• pp.135-153
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• 2000

Shoes originated from the practical purposes : to protect feet from heat, cold. etc., and developed into various shapes. representing ornamentation and hierarchy. It was revealed that the aesthetic value was differently manifested from the practical one by different natural environments and socio-cultural Phenomena of the times in the East and the West. Comparing shoes in the East with those in the West, this study finds out the origin of shoes in the East and the West, and shapes and characteristics of shoes through the changes of times. Investigating various kinds of shoes in the East and the West, it also finds out the differences in status representations. Shoes are classified into the following styles : in the West. (i) sandal in which the instep was almost exposed, tied with strips and fixed with band, (ii) closed shoes covering the instep, (iii) boots that arose above the ankle: in the East, (i) shoes without shoe neck (리) boots with shoe neck (화) and wooden shoes (극). Status was also represented in shoes. In the West. the status difference was manifested mainly by jewelry or embroidery ornamentation. In particular, it was realized by the way they tied the shoes in Rome and by the length of the pointed front of the shoes in Romanesque and Gothic period. In the East, China, Korea and Japan, on the other hand, the use of shoes was regulated in detail by the official costume system, where material and color played an important role in marking the status.

• Particle and aerosol research
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• v.17 no.4
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• pp.107-114
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• 2021

In this study, the effect of the air purifier located in the living room on the reduction of PM_2.5 concentration in the living room and bedroom was investigated. Measurements were carried out in real-life for about 2 weeks in a Korean apartment building where a 3-person household had lived and the exclusive private area was 84.9 m². When the air purifier in the living room was operating, the change in PM_2.5 concentration was measured when the door to the bedroom connected to the living room was opened and closed. In the case of living with the bedroom door open, the average PM_2.5 concentrations in the living room and bedroom were almost the same. When living with the bedroom door closed, the average PM_2.5 in the living room was higher than in the bedroom. The ventilation and cooking effects in the living room mainly affected the PM_2.5 concentration in the living room. Only one air purifier in the living room was able to keep the PM_2.5 concentration in the living room and bedroom low.

• Communications of the Korean Mathematical Society
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• v.26 no.1
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• pp.135-149
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• 2011

Using (r, s)-preopen sets [14] and pre-${\omega}_t$-closures [6], a new kind of covering property $P^t_{({\omega}_r,s)}$-closedness is introduced in a bitopological space and several characterizations via filter bases, nets and grills [30] along with various properties of such concept are investigated. Two new types of cluster sets, namely pre-(${\omega}_r$, s)t-${\theta}_f$-cluster sets and (r, s)t-${\theta}_f$-precluster sets of functions and multifunctions between two bitopological spaces are introduced. Several properties of pre-(${\omega}_r$, s)t-${\theta}_f$-cluster sets are investigated and using the degeneracy of such cluster sets, some new characterizations of some separation axioms in topological spaces or in bitopological spaces are obtained. A sufficient condition for $P^t_{({\omega}_r,s)}$-closedness has also been established in terms of pre-(${\omega}_r$, s)t-${\theta}_f$-cluster sets.

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.44 no.4 s.316
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• pp.70-77
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• 2007

Two kinds of QMF(Quadrature Mirror Filter) pairs are used in JPEG2000 standard, which don't have QMF distortions. However, the QMF pairs have the main disadvantages such that there are gentle roll-off rate, ripples in the passband and unequal band decomposition. In this paper, Maxflat(maximally flat) QMF pairs with a half-band gain are proposed for overcoming these problems. Maxflat QMF pairs are realized due to generalized closed-form formulas, and the filters have maximally flat response in the passband/stopband as well as sharp roll-off rate in the transition band. Comparing proposed filters and JPEG2000's filters in frequency domain, it is found that proposed filters have better performance JPEG2000's filters. Moreover, Maxflat QMF pairs show stopband-attenuation exceeding 200 dB almost everywhere.

• Archives of Craniofacial Surgery
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• v.18 no.2
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• pp.92-96
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• 2017

Background: All nasal bone fractures have the potential for worsening of olfactory function. However, few studies have studied the olfactory outcomes following reduction of nasal bone fractures. This study evaluates posttraumatic olfactory dysfunction in patients with nasal bone fracture before and after closed reduction. Methods: A prospective study was conducted for all patients presenting with nasal bone fracture (n=97). Each patient consenting to the study underwent the Korean version of Sniffin' Sticks test (KVSS II) before operation and at 6 month after closed reduction. The nasal fractures were divided according to the nasal bone fracture classification by Haug and Prather (Types I-IV). The olfactory scores were compared across fracture types and between preoperative and postoperative settings. Results: Olfactory dysfunction was frequent after nasal fracture (45/97, 46.4%). Our olfactory assessment using the KVSS II test revealed that fracture reduction was not associated with improvements in the mean test score in Type I or Type II fractures. More specifically, the mean posttraumatic Threshold, discrimination and identification score decreased from 28.8 points prior to operation to 23.1 point at 6 months for Type II fracture with septal fracture. Conclusion: Our study has revealed two alarming trends regarding post-nasal fracture olfactory dysfunction. First, our study demonstrated that almost half (46.4%) of nasal fracture patients experience posttraumatic olfactory dysfunction. Second, closed reduction of these fractures does not lead to improvements olfaction at 6 months, which suggest that olfactory dysfunction is probably due to factors other than the fracture itself. The association should be further explored between injuries that lead to nasal fracture and the mechanism behind posttraumatic olfactory dysfunction.

• Design & Manufacturing
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• v.10 no.2
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• pp.18-23
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• 2016

Injection molded thermoplastic parts may need to be coated to facilitate paint adhesion, or to satisfy other surface property requirements, such as appearance, durability, and weather resistance. In this paper, a two-component polyurethane metering system was developed for the simultaneous injection and surface coating of a plastic substrate. The system was composed of storage tanks, feed pumps, axial piston pumps, mixing head. The tank was designed to be double-jacket structured and fabricated for polyol and isocyanate, respectively. A temperature chamber was used to maintain the material temperature to be $80^{\circ}C$ during flowing from storage tank to mixing head. Inside the chamber, feed pump, low pressure filter, high pressure pump, high pressure filter, pressure sensor, flow meter were installed. A mixing head of L-type was used for homogeneous mixing of polyol and isocyanate. Inside the mixing head, a cartridge heater and a temperature sensor were installed to control the temperature of the materials. The flow rate of axial-piston pump was controlled by using closed-loop feedback control algorithm. The input flow-rates were compared with the measured values. The output error was 6.7% for open-loop control, whereas the error was below 2.2% for closed-loop control. In addition, the pressure generated through mixing-head nozzle increased with increasing flow rate. It was found that the pressure drop between metering pump and mixing-head nozzle was almost 10 bar.