• Membrane Journal
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• v.34 no.1
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• pp.58-69
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• 2024

Reverse electrodialysis (RED) is an electro-membrane process employing ion-exchange membranes (IEMs) that can harvest electric energy from the concentration difference between seawater and river water. Multivalent ions contained in seawater and river water bind strongly to the fixed charge groups of the IEM, causing high resistance and reducing open-circuit voltage and power density through uphill transport. In this study, a pore-filled anion-exchange membrane (PFAEM) with excellent monovalent ion selectivity and electrochemical properties was fabricated and characterized for RED application. The monovalent ion selectivity of the prepared membrane was 3.65, which was superior to a commercial membrane (ASE, Astom Corp.) with a selectivity of 1.27 under the same conditions. Additionally, the prepared membrane showed excellent electrochemical properties, including low electrical resistance compared to ASE. As a result of evaluating RED performance under seawater of 0.459 M NaCl/0.0510 M Na₂SO₄ and river water of 0.0153 M NaCl/0.0017 M Na₂SO₄, the maximum power density of 1.80 W/m² was obtained by applying the prepared membrane, which is a 40.6% improved output performance compared to the ASE membrane.

• Journal of the Korean Society for Marine Environment & Energy
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• v.8 no.2
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• pp.60-66
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• 2005

When external pressure higher than osmosis pressure is reversely derived into solution, its solvent is moved into the solution having lower concentration, which is called 'reverse osmosis'. We investigated the desalination application of deep ocean water using reverse osmosis pressure of $40-70\;kgf/cm^2$ We observed how to operational factor j like flow rate, water temperature and pressure have effect on efficiency of reverse osmosis membrane and salts rejection. Fluxes of reverse osmosis membrane are directly proportional to water temperature and pressure. However, salts rejection rates are positively correlated with pressure and inversely proportional to water temperature. Separation efficiencies of osmosis membrane for major elements such as $Mg^{2+},\;Ca^{+2},\;Na^+\;and\;K^+$ are as follows in a strong electrolysis solution like seawater; $Ca^{2+},\;Mg^{2+}>K^+>Na^+$. Rejection rates of $Mg^{2+}\;and\;Ca^{2+}$ that have high electric charges are over 99% and show positively correlation with water temperature. Rejection rates of $Na^+$ having low electric charge is observed to be 98%-99%, which rates is much lower than those of $2^+$ charged ions like $Ca^{2+}\;and\;Mg^{2+}$. Ion rejection rates of boron, B, are much low because boron is present il free state or gas phase in seawater. Boron concentration in desalination water is over criteria of Korean drinking water, 0.3 mg/L. However, we could satisfied with the criteria of drinking water under the operation condition like temperature $5^{\circ}C$ and pressure $70kgf/cm^2$, using the relationship that rejection rates of boron is proportional to pressure and is inversely proportional to water temperature

• The Korean Journal of Nuclear Medicine Technology
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• v.15 no.2
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• pp.104-110
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• 2011

Purpose: The object evaluation method about medical institutes of these days increases credibility of consumers about medical services by conducting a certification system about medical institutes. In addition, as nuclear medicine test rooms and diagnosis test medicine room adopt many kinds of international certification systems, the matters regarding safety management of test rooms are being regarded as important. Since the blood test rooms of nuclear medicine are exposed to many harmful factors such as infection from clinical specimen and radioactive isotope reagent, there is a need to pay lots of attention to the safety management of staff and patients. Therefore, this study discusses safety management activities of staff and patients, which are conducted in the blood test rooms of the nuclear medicine department in Asan Medical Center. Materials and Methods: In the blood test rooms of the nuclear medicine department in Asan Medical Center, the matters regarding comprehensive safety management by the person in charge of safety management are offered and all staff members of the test rooms apply them into work. Safety management education is regularly conducted according to established regulations, and infection is prevented through implementation of wearing personal protectors and hand sanitation during test work. In addition, technical safety guides and accident guides for interruption of electric power are provided against emergencies. Through infection management guides, infection prevention and preparation methods for infection are learned and radioactive isotope management, safety management about reagent use and safety guides about harmful chemical substances are being applied to work. Results: The blood test rooms of the nuclear medicine department apply safety management regulations to work. Under the situation where hand sanitation should be conducted, hands are washed to prevent infection between staff and patients, and for preventing infection from clinical specimen, personal protectors are worn. The reagent, which is classified as harmful substance, is separately stored to be easily recognized, radioactive wastes and general medical wastes are also safely managed. Through these lots of safety management activities, safety management awareness of staff members is enhanced, and patients are protected from many dangers. Conclusion: Staff members of the blood test rooms of the nuclear medicine department should be fully aware of safety management regulations and apply them to work. When better safety management suggestions are made, they need to be examined and applied for increasing quality of safety management for staff and patients.

• Korean Security Journal
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• no.13
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• pp.423-449
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• 2007

This research is to investigate the detention facilities of police stations and their real operations through the perceptions of detainees at police station cells and to present the policy suggestions for them. To fulfill the research, a questionnaire was made out on the basis of 'the Regulation on Detention and Escort for Suspects'. 'the Regulation on a Standard Plan for Detention Facilities' and 'the Regulation on the Lowest Standard to Treat Detainees' ; and detainees at 23 police station cells under the jurisdiction of Kyungbuk Local Police Agency were asked to answer it. Policy suggestions following from the result of the investigation of detainees' perceptions of the detention facilities of the police stations are as follows; Firstly, the structure of police station cells should be arranged in straight lines in order to take their human rights into consideration and more detention facilities are needed to be built in order to separate male, female, handicapped and juvenile inmates. Secondly, shower rooms and washrooms outside the cells should always be open to detainees whenever they need to be used. Thirdly, any detention facilities deficient in fire fighting equipment should have exit doors installed as soon as possible in case of an emergency and provide sufficient fire extinguishers considering the number of detainees and the size of the facilities. Fourthly, the detention facilities should have sufficient windows for ventilation and take necessary measures to obtain natural lighting instead of electric lighting. Fifthly, air conditioners should be equipped properly taking account of the number of detainees and the dimensions of the facilities. Policy suggestions according to the result of the investigation of detainees' perceptions of the operation of detention facilities of police stations are as follows; Firstly, the problem of operating the detention facilities must deal with worn-out facilities and measures to secure the budget should be taken as soon as possible. Secondly, considering that most detained suspects have difficulties in livelihood, daily necessaries must be issued to them. Thirdly, personal belongings deposited by inmates must be properly managed with the same documentation throughout the police station detention facilities. The number of female guards to take exclusive charge of the physical checkups and processing of female detainees should be increased. Also the facilities for handicapped detainees must be expanded, improved and managed properly. Fourthly, except for handcuffs and ropes to bind detainees in the detention facilities, helmets to prevent self-harm must be withdrawn. The budget to improve the quality of meal issued by the government must be urgently secured and the price of private food sent to detainees must be readjusted to be in line with the consumer price. Health and medical care and sanitation for detainees must be substantial, and also sunbathing and outdoor exercises should be allowed to detainees.

• Journal of the Korean Magnetics Society
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• v.16 no.1
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• pp.6-10
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• 2006

The sulphur spinel $FeCr_{2-x}M_xS_4$(M=Ga, In) have been studied with Mossbauer spectroscopy, x-ray diffraction (XRD), and vibrating sample magnetometer. The XRB patterns for samples $FeCr_{2-x}M_xS_4$(M=Ga, In: x=0.1, 0.3) reveal a single phase, which the Ga and In ions are partially occupied to the tetrahedral (A) site. The Neel temperature for the Ga substituted samples increases from 180 to 188 K, with increase from x=0.1 to 0.3. While, it decreases from 173 to 160 K, for the In substituted samples of the x=0.1 and 0.3, respectively. The Mossbauer spectra were collected from 4.2 K to room temperature. We have analyzed the Mossbauer spectra using eight Lorentzian lines fitting method for the $FeCr_{2-x}In_xS_4$(x=0.1) at 4.2 K, yielding the 1311owing results; $H_{hf}=146.0kOe,\;{\Delta}E_Q=1.88mm/s,\;\theta=36^{\circ},\;\phi=0^{\circ},\;\eta=0.6$, and R=1.9. The Ga ions enter into the both sites octahedral (B) and tetrahedral (A), simultaneously the same amounts of Fe ions migrate from the A to the B site, this result is an agreement with XRD results, too. The ${\Delta}E_Q$ of the A and B site in Mossbauer spectra of the samples $FeCr_{2-x}Ga_xS_4$(x=0.3) are 0.83 and 2.94mm/s, respectively. While they are 0.56 and 2.36mm/s for the $FeCr_{2-x}In_xS_4$(x=0.3). It is noticeable that the ${\Delta}E_Q$ for the Ga doped samples are larger than that of the corresponding In doped samples, in spite of the larger ionic radius for In ions. The bond lengths of Cr-S, for the Ga and In doped samples (x=0.3) are found to be 2.41 and $2.43\;{\AA}$, respectively. We interpret that the larger covalence effect from the smaller bond length induces a large asymmetric charge distribution. Finally, it gives a large quadrupole interaction.

• Korean Chemical Engineering Research
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• v.60 no.1
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• pp.93-99
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• 2022

With the rapid development of ultra-small and wearable device technology, continuous electricity supply without spatiotemporal limitations for driving electronic devices is required. Accordingly, Triboelectric nanogenerator (TENG), which utilizes static electricity generated by the contact and separation of two different materials, is being used as a means of effectively harvesting various types of energy dispersed without complex processes and designs due to its simple principle. However, to apply the TENG to real life, it is necessary to increase the electrical output. In addition, stable generation of electrical output, as well as increase in electrical output, is a task to be solved for the commercialization of TENG. In this study, we proposed a method to not only improve the output of TENG but also to stably represent the improved output. This was solved by using the contact layer, which is one of the components of TENG, as an electret for improved output and stability. The utilized electret was manufactured by sequentially performing corona charging-thermal annealing-corona charging on the Fluorinated ethylene propylene (FEP) film. Electric charges artificially injected due to corona charging enter a deep trap through the thermal annealing, so an electret that minimizes charge escape was fabricated and used in TENG. The output performance of the manufactured electret was verified by measuring the voltage output of the TENG in vertical contact separation mode, and the electret treated to the corona charging showed an output voltage 12 times higher than that of the pristine FEP film. The time and humidity stability of the electret was confirmed by measuring the output voltage of the TENG after exposing the electret to a general external environment and extreme humidity environment. In addition, it was shown that it can be applied to real-life by operating the LED by applying an electret to the clap-TENG with the motif of clap.