• The Korean Journal of Nuclear Medicine
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• v.28 no.1
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• pp.124-132
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• 1994

Radioactive iodine has been widely used in patients with thyroid cancer combined with surgical treatment. However, due to individual variations in absorption and excretion and uptake by tumor tissue of radioactive iodine, there are differences in therapeutic effect and adverse effects even if the same doses are administrated. So this study compared the therapeutic effect and radiation hazard by measuring internal radiation dose. Of total 27 patients with well differentiated thyroid cancer who had been thyroidectomized, we administered radioactive iodine 100 mCi, 150 mCi, 200 mCi. According to BEL DOSIMETRY PROTO-COL, beta and gamma ray dose were estimated from a pelt of the logarithm of the percent of dose per liter of whole blood versus day, and percent dose retained versus day using somilogarithmic paper, respectively. 1) Physical dose to whole blood averaged $56.54{\pm}13.02$ rad in 100 mCi administered group, $76.83{\pm}19.97$ rad in 150 mCi administered group, $95.08{\pm}25.51$ rad in 200 mCi administered group and there has been a significant correlation among the groups. 2) Mean percent dose retained 48 hours later was 26.34%. 3) There was no significant correlation of physical dose between absence and presence of metastasis. 4) 17 of 19 patients who has been followed up with TSH and serum throglobulin, Thallium scan were successfully ablated by radioactive iodine. 5) Leukocyte, lymphocyte, neutrophil, platelet counts all deelined in 4.6 weeks and most of all were restored 3 months later. 6) There was no significant correlation between physical dosimetry and biologic dosimetry. Generally administered doses of radioactive iodine (100-200 mCi) to patients with thyroid cancer postoperatively had developed transient bone marrow suppression and minimal chromosomal aberration, but they were within safety dose to blood (200 rad). And there has been no significant differences in residual dose 48 hours later between Korean and western people.

• Korean Chemical Engineering Research
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• v.53 no.5
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• pp.620-626
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• 2015

$Ho^{3+}$ doped $SrAl_2O_4$ upconversion phosphor powders were synthesized by spray pyrolysis, and the crystallographic properties and luminescence characteristics were examined by varying activator concentrations and heattreatment temperatures. The effect of organic additives on the crystal structure and luminescent properties was also investigated. $SrAl_2O_4:Ho^{3+}$ powders showed intensive green emission due to the $^5F_4/^5S_2{\rightarrow}^5I_8$ transition of $Ho^{3+}$. The optimal $Ho^{3+}$ concentration in order to achieve the highest luminescence was 0.1%. Over this concentration, emission intensities were largely diminished via a concentration quenching due to dipole-dipole interaction between activator ions. According to the dependence of emission intensity on the pumping power of a laser diode, it was clear that the upconversion of $SrAl_2O_4:Ho^{3+}$ occurred via the ground state absorption-excited state absorption processes involving two near-IR photons. Synthesized powders were monoclinic as a major phase, having some hexagonal phase. The increase of heat-treatment temperatures from $1000^{\circ}C$ to $1350^{\circ}C$ led to crystallinity enhancement of monoclinic phase, reducing hexagonal phase. The hexagonal phase, however, did not disappear even at $1350^{\circ}C$. When both citric acid (CA) and ethylene glycol (EG) were added to the spray solution, the resulting powders had pure monoclinic phase without forming hexagonal phase, and led to largely enhancement of crystallinity. Also, N,N-Dimethylformamide (DMF) addition to the spray solution containing both CA and EG made it possible to effectively reduce the surface area of $SrAl_2O_4:Ho^{3+}$ powders. Consequently, the $SrAl_2O_4:Ho^{3+}$ powders prepared by using the spray solution containing CA/EG/DMF mixture as the organic additives showed about 168% improved luminescence compared to the phosphor prepared without organic additives. It was concluded that both the increased crystallinity of high-purity monoclinic phase and the decrease of surface area were attributed to the large enhancement of upconversion luminescence.

• Journal of Life Science
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• v.28 no.2
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• pp.153-161
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• 2018

Hot-air and freeze dried powder from aged black ginger were mixed under the ratio conditions of sample "A" (8:2), "B" (5:5), "C"(2:8), "D" (10:0) and "E" (0:10), respectively. The physicochemical properties and antioxidant activities in the 5 kinds of powder were compared. The water absorption index was significantly higher in freeze dried powder, and it tended to be significantly increased depend on the ratio of freeze dried sample. The browning intensity was significantly higher in the hot-air dried samples, but the color intensity was not significant. Total and reducing sugar contents were significantly higher in freeze dried sample. Total sugar content in mixed sample tended to significantly increased as the amount of freeze dried sample. Total phenol content was significantly higher in the sample "A". The contents of gingerol and shogaol were significantly higher in mixed sample "A", 6-gingerol content showed no significant difference according to the drying method. Cholesterol absorption activity was significantly higher in the freeze dried sample "E". The DPPH radical scavenging activity showed a little difference according to the drying method, but the ABTS radical scavenging activity and reducing power in the hot-air dried sample were significantly higher than those of freeze dried. And the activity of mixed powder "A" was significantly higher than others. These results suggest that aged black ginger was superior in terms of quality and functionality of the hot-air drying compared to freeze-drying, and it would be economically effective to the mixed sample "A".

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.12 no.12
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• pp.1098-1125
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• 2000

A review on the papers published in the Korean Journal of Air-Conditioning and Refrigerating Engineering in 1998 and 1999 has been done. Focus has been put on current status of research in the aspect of heating, cooling, ventilation, sanitation and building environment. The conclusions are as follows. 1) A review of the recent studies on fluid flow, turbomachinery and pipe-network shows that many experimental investigations are conducted in applications of impingement jets. Researches on turbulent flows, pipe flows, pipe-networks are focused on analyses of practical systems and prediction of system performance. The results of noise reduction in the turbomachinery are also reported. 2) A review of the recent studies on heat transfer analysis and heat exchanger shows that there were many papers on the channel flow with the application to the design of heat exchanger in the heat transfer analysis. Various experimental and numerical papers on heat exchanger were also published, however, there were few papers available for the analysis of whole system including heat exchanger. 3) A review of the recent studies on heat pump system have focused on the multi-type system and the heat pump cycle to utilize treated sewage as the heat source. The defrosting and the frosting behaviors in the fin-tube heat exchanger is experimentally examined by several authors. Several papers on the ice storage cooling system are presented to show the dynamic simulation program and optimal operation conditions. The study on the micro heat pipes for the cooling of high power electronic components is carried out to examine the characteristics of heat and mass transfer processed. In addition to these, new type of separate thermosyphon is studied experimentally. 4) The recent studies on refrigeration/air conditioning system have focused on the system performance and efficiency for new alternative refrigerants. New systems operating with natural refrigerants are drawing lots of attention. In addition to these, evaporation and condensation heat transfer characteristics of traditional and new refrigerants are investigated for plain tubes and also for microfin tubes. Capillary tubes and orifice are main topics of research as expansion devices and studies on thermophysical properties of new refrigerants and refrigerant/oil mixtures are widely carried out. 5) A review of the recent studies on absorption cooling system shows that numerous experimental and analytical studies on the improvement of absorber performance have been presented. Dynamic analysis of compressor have been performed to understand its vibration characteristics. However research works on tow-phase flow and heat transfer, which could be encountered in the refrigeration system and various phase-change heat exchanger, were seemed to be insufficient. 6) A review of recent studies on duct system shows that the methods for circuit analysis, and flow balancing have been presented. Researches on ventilation are focused on the measurement of ventilation efficiency, and variation of ventilation efficiency with ventilation methods by numerous experimental and numerical studies. Furthermore, many studies have been conducted in real building in order to estimate indoor thermal environments. Many research works to get some information for cooling tower design have been performed but are insufficient. 7) A review on the recent studies on architectural thermal environment and building mechanical systems design shows that thermal comfort analysis is sitting environment, thermal performance analysis of Korean traditional building structures., and evaluation of building environmental load have been performed. However research works to improve the performance of mechanical system design and construction technology were seemed to be insufficient.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.15 no.6
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• pp.252-259
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• 2005

Single crystal $CuGaSe_2$ layers were grown on thoroughly etched semi-insulating CaAs(100) substrate at $450^{\circ}C$ with hot wall epitaxy (HWE) system by evaporating $CuGaSe_2$ source at $610^{\circ}C$. The crystalline structure of the single crystal thin films was investigated by the photoluminescence (PL) and double crystal X-ray diffraction (DCXD). The carrier density and mobility of single crystal $CuGaSe_2$ thin films measured with Hall effect by Van der Pauw method are $4.87{\times}10^{17}cm^{-3}$ and $129cm^2/V{\cdot}s$ at 293 K, respectively. The temperature dependence of the energy band gap of the $CuGaSe_2$ obtained from the absorption spectra was well described by the Varshni's relation, $E_g(T)=1.7998eV-(8.7489{\times}10^{-4}eV/K)T^2/(T+335K)$. The voltage, current density of maxiumun power, fill factor, and conversion, efficiency of $n-CdS/p-CuGaSe_2$, heterojunction solar cells under $80mW/cm^2$ illumination were found to be 0.41 V, $21.8mA/cm^2$, 0.75 and 11.17%, respectively.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.36 no.6
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• pp.669-674
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• 2012

D-Cube City is a recently completed multi purpose building consisting of four types of facilities; offices, a department store, a hotel, and congregation spaces. A community energy supply system(CES) has been installed to supply this building with electricity, steam, heat, and cold water. The BEMS, building energy management system, is currently being designed to reduce building energy consumption through the efficient operation of the various pieces of building service equipment. In this study the optimal methods for operating the CES of D-Cube City were considered. This system includes three combined heat and power systems, seven steam boilers, two hot water boilers, two absorption chillers, and four turbo chillers, and various other pieces of equipment. In result, the optimal methods of operating the CES for various energy demand levels were obtained along with the seasonal effects on the economic efficiency of the operation. The effect of the amount of energy demanded by the various facility areas on the total energy consumption was also analyzed.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.22 no.12
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• pp.1107-1115
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• 2011

In this paper, a headset multiple-input multiple-output(MIMO) antenna for on-body application is proposed and the antenna performance with body effect and the impact on human body are investigated. The proposed MIMO antenna is composed of two planar inverted-F antennas(PIFA) above ground plane and an isolator located between the two antennas enhance the isolation characteristic. Simulation was carried to analyze the effect of human body on antenna performance when a human body is located in the near field of the antenna. According to the measurement result, the diversity performance of the proposed antenna can be considered good since ECC(Envelope Correlation Coefficient), which commonly indicates the performance of a MIMO antenna, remains below 0.1 over the ISM band. The measured SAR values for antennas 1 and 2 are 0.575 W/kg and 0.571 W/kg, respectively when 250 mW input power in engaged. These values satisfy the FCC guideline which states that the 1-g average SAR should be lower than 1.6 W/kg.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.23 no.2
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• pp.213-219
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• 2012

Recently, we are simultaneously exposed by various electromagnetic sources due to an increase of mobile communication services. However, EMF(Electric, Magnetic and Electromagnetic Field) study has been performed mainly about only single frequency. The objective of this paper is to develop an multiple-frequency exposure system for in vitro experiment. The exposure unit for in vitro experiments was designed by radial transmission line type to get broadband characteristics to generate signals of CDMA at 836.5 MHz and WCDMA at 1950 MHz frequency simultaneously. The modulated signals were delivered to the conical antenna through amplifier, digital attenuator and RF combiner. SAR values were obtained by the averaged values of 3 measured values at 9 points in petri dish using the fiber optic temperature probe. The measured return loss was under -15 dB. For 1 W input power, the mean value and standard deviation of SAR were $0.105{\pm}0.019$ for the CDMA frequency and $0.262{\pm}0.055$ for the WCDMA frequency.

• Proceedings of the Korean Vacuum Society Conference
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• 2012.08a
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• pp.189-189
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• 2012

Lead sulfide (PbS) nanocrystal quantum dots (NQDs) are promising materials for various optoelectronic devices, especially solar cells, because of their tunability of the optical band-gap controlled by adjusting the diameter of NQDs. PbS is a IV-VI semiconductor enabling infrared-absorption and it can be synthesized using solution process methods. A wide choice of the diameter of PbS NQDs is also a benefit to achieve the quantum confinement regime due to its large Bohr exciton radius (20 nm). To exploit these desirable properties, many research groups have intensively studied to apply for the photovoltaic devices. There are several essential requirements to fabricate the efficient NQDs-based solar cell. First of all, highly confined PbS QDs should be synthesized resulting in a narrow peak with a small full width-half maximum value at the first exciton transition observed in UV-Vis absorbance and photoluminescence spectra. In other words, the size-uniformity of NQDs ought to secure under 5%. Second, PbS NQDs should be assembled carefully in order to enhance the electronic coupling between adjacent NQDs by controlling the inter-QDs distance. Finally, appropriate structure for the photovoltaic device is the key issue to extract the photo-generated carriers from light-absorbing layer in solar cell. In this step, workfunction and Fermi energy difference could be precisely considered for Schottky and hetero junction device, respectively. In this presentation, we introduce the strategy to obtain high performance solar cell fabricated using PbS NQDs below the size of the Bohr radius. The PbS NQDs with various diameters were synthesized using methods established by Hines with a few modifications. PbS NQDs solids were assembled using layer-by-layer spin-coating method. Subsequent ligand-exchange was carried out using 1,2-ethanedithiol (EDT) to reduce inter-NQDs distance. Finally, Schottky junction solar cells were fabricated on ITO-coated glass and 150 nm-thick Al was deposited on the top of PbS NQDs solids as a top electrode using thermal evaporation technique. To evaluate the solar cell performance, current-voltage (I-V) measurement were performed under AM 1.5G solar spectrum at 1 sun intensity. As a result, we could achieve the power conversion efficiency of 3.33% at Schottky junction solar cell. This result indicates that high performance solar cell is successfully fabricated by optimizing the all steps as mentioned above in this work.

• Clean Technology
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• v.19 no.2
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• pp.165-172
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• 2013

In this study, the hydrogen chloride removal using K-based dry sorbents ($K_2CO_3/Al_2O_3$, KEPRI, Korea) was studied with varying the pressure in a fixed bed reactor (15 cm tall bed with 0.5 cm I.d.). Working temperature was $400^{\circ}C$ and feed gas concentration was 750 ppm (HCl vol%, $N_2$ balance). The chloride sorption capacity of sorbent increases with increasing pressure (1, 5, 10, 15 and 20 bar). Also, after forming KCl crystal by reaction with $K_2CO_3$ and HCl, owing to the strong bonding energy, sorbent regeneration was practically impossible. Its optical, physical and chemical characterizations were evaluated by SEM, EDAX, BET, TGA and XRD. At $400^{\circ}C$ and 20 bar condition, working condition for the dehalogenation process after gasification, K-based dry sorbent showed high HCl sorption capacity and HCl/$N_2$ separation performances comparing with Ca-based and Mg-based dry sorbents.