• Progress in Medical Physics
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• v.2 no.2
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• pp.109-120
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• 1991

Total body irradiation is operated to irradicate malignant cells of bone marrow of patients to be treated with bone marrow transplantation. Field size of a linear accelerator or cobalt teletherapy unit with normal geometry for routine technique is too small to cover whole body of a patient. So, any special method to cover patient whole body must be developed. Because such environments as room conditions and machine design are not universal, some characteristic method of TBI for each hospital could be developed. At Seoul National University Hospital, at present, only a cobalt unit is available for TBI because source head of the unit could be tilted. When the head is tilted outward by 90$^{\circ}$, beam direction is horizontal and perpendicular to opposite wall. Then, the distance from cobalt source to the wall was 319 cm. Provided that the distance from the wall to midsagittal plane of a patient is 40cm, nominal field size at the plane(SCD 279cm) is 122cm$\times$122cm but field size by measurement of exposure profile was 130cm$\times$129cm and vertical profile was not symmetric. That field size is large enough to cover total body of a patient when he rests on a couch in a squatting posture. Assuming that average lateral width of patients is 30cm, percent depth dose for SSD 264cm and nominal field size 115.5cm$\times$115.5cm was measured with a plane-parallel chamber in a polystyrene phantom and was linear over depth range 10～20cm. An anthropomorphic phantom of size 25cm wide and 30cm deep. Depth of dose maximum, surface dose and depth of 50% dose were 0.3cm, 82% and 16.9cm, respectively. A dose profile on beam axis for two opposing beams was uniform within 10% for mid-depth dose. Tissue phantom ratio with reference depth 15cm for maximum field size at SCD 279cm was measured in a small polystyrene phantom and was linear over depth range 10～20cm. An anthropomorphic phantom with TLD chips inserted in holes on the largest coronal plane was bilaterally irradiated by 15 minute in each direction by cobalt beam aixs in line with the cross line of the coronal plane and contact surface of sections No. 27 and 28. When doses were normalized with dose at mid-depth on beam axis, doses in head/neck, abdomen and lower lung region were close to reference dose within $\pm$ 10% but doses in upper lung, shoulder and pelvis region were lower than 10% from reference dose. Particulaly, doses in shoulder region were lower than 30%. On this result, the conclusion such that under a geometric condition for TBI with cobalt beam as SNUH radiotherapy departement, compensators for head/neck and lung shielding are not required but boost irradiation to shoulder is required could be induced.

• Asia pacific journal of information systems
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• v.20 no.4
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• pp.101-123
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• 2010

Recently, firms are operating a number of teams to accomplish organizational performance. Especially, ad hoc teams like proposal preparation team are quite different from permanent teams like R&D team in the sense of how the team forms network structure and deals with organizational learning culture and knowledge management participation efforts. Moreover, depending on the team characteristics, individual creativity will differ from each other, which will lead to organizational performance eventually. Previous studies in the field of creativity are lacking in this issue. So main objectives of this study are organized as follows. First, the issue of how to improve individual creativity and organizational performance will be analyzed empirically. This issue will be performed depending on team characteristics such as ad hoc team and permanent team. Antecedents adopted for this research objective are cultural and knowledge factors such as organizational learning culture, and knowledge management participation. Second, the network structure such as degree centrality, and structural hole is used to analyze its influence on individual creativity and organizational performance. SI (System Integration) companies are facing severely tough requirements from clients to submit very creative proposals. Also, R&D teams are widely accepted as relatively creative teams because their responsibilities are focused on suggesting innovative techniques to make their companies remain competitive in the market. SI teams are usually ad hoc, while R&D teams are permanent on an average. By taking advantage of these characteristics of the two kinds of teams, we will prove the validity of the proposed research questions. To obtain the survey data, we accessed 7 SI teams (74 members), and 6 R&D teams (63 members), collecting 137 valid questionnaires. PLS technique was applied to analyze the survey data. Results are as follows. First, in case of SI teams, organizational learning culture affects individual creativity significantly. Meanwhile, knowledge management participation has a significant influence on Individual creativity for the permanent teams. Second, degree centrality Influences individual creativity significantly in case of SI teams. This is comparable with the fact that structural hole has a significant impact on individual creativity for the R&D teams. Practical implications can be summarized as follows: First, network structure of ad hoc team should be designed differently from one of permanent team. Ad hoc team is supposed to show a high creativity in a rather short period, implying that network density among team members should be improved, and those members with high degree centrality should be encouraged to show their Individual creativity and take a leading role by allowing them to get heavily engaged in knowledge sharing and diffusion. In contrast, permanent team should be designed to take advantage of structural hole instead of focusing on network density. Since structural hole can be utilized very effectively in the permanent team, strong arbitrators' merits in the permanent team will increase and therefore helps increase both network efficiency and effectiveness too. In this way, individual creativity in the permanent team is likely to lead to organizational creativity in a seamless way. Second, way of Increasing individual creativity should be sought from the perspective of organizational culture and knowledge management. Organization is supposed to provide a cultural atmosphere in which Innovative idea suggestions and active discussion among team members are encouraged. In this way, trust builds up among team members, facilitating the formation of organizational learning culture. Third, in the ad hoc team, organizational looming culture should be built such a way that individual creativity can grow up fast in a rather short period. Since time is tight, reasonable compensation policy, leader's Initiatives, and learning culture formation should be done In a short period so that mutual trust is built among members quickly, and necessary knowledge and information can be learnt rapidly. Fourth, in the permanent team, it should be kept in mind that the degree of participation in knowledge management determines level of Individual creativity. Therefore, the team ought to facilitate knowledge circulation process such as knowledge creation, storage, sharing, utilization, and learning among team members, which will lead to team performance. In this way, firms must control knowledge networks in permanent team and ad hoc team in a way mentioned above so that individual creativity as well as team performance can be maximized.

• Journal of Chest Surgery
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• v.12 no.4
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• pp.383-394
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• 1979

Treatment of valvular heart disease with valve replacement has been one of the most popular procedures in cardiac surgery recently. Although, first effort was directed toward the prosthetic valve, it soon became popular that bioprosthesis, the valvular xenograft, was prefered in the majority cases. Valvular xenograft has some superiority to the artificial prosthetic valve in some points of thromboembolism and hemolytic anemia, and it also has some inferiority of durability, immunologic reaction and resistance to Infection. Tremendous efforts were made to cover the inferiority with several methods of collection, preservation, and valve mounting of the porcine valve or pericardium of the calf, and also with surgical technique of the valvular xenograft replacement. Auther has collected 320 porcine aortic valves immediately after slaughter, and aortic cusps were coapted with cotton balls in the Valsalva sinuses to protect valve deformity after immersion in the Hanks' solution, and oxidation, cross-linking and reduction procedures were completed after the proposal of Carpentier in 1972. Well preserved aortic valves were suture mounted in the hand-made tissue valve frame of 19, 21, and 23 mm J.d., and also in the prosthetic vascular segment of 19 mm Ld. with 4-0 nylon sutures after careful trimming of the aortic valves. Completed valves were evaluated with bacteriologic culture, pressure tolerance test with tolerane gauge, valve durability test in the saline glycerine mixed solution with tolerance test machine in the speed of 300 rpm, and again with pathologic changes to obtain following results: 1. Bacteriologic culture of the valve tissue in five different preservation method for two weeks revealed excellent and satisfactory result in view of sterilization including 0.65% glutaraldehyde preservation group for one week bacteriologic culture except one tissue with Citobacter freundii in 75% ethanol preserved group. 2. Pressure tolerance test was done with an apparatus composed of V-connected manometer and pressure applicator. Tolerable limit of pressure was recorded when central leaking jet of saline was observed. Average pressure tolerated in each group was 168 mmHg in glutaraldehyde, 128 mmHg in formaldehyde, 92 mmHg in Dakin's solution, 48 mmHg in ethylene oxide gas, and 26 mmHg in ethanol preserved group in relation to the control group of Ringer's 90 mmHg respectively. 3. Prolonged durability test was performed in the group of frame mounted xenograft tissue valve with 300 up-and-down motion tolerance test machine/min. There were no specific valve deformity or wearing in both 19, 21, and 23 mm valves at the end of 3 months (actually 15 months), and another 3 months durability test revealed minimal valve leakage during pressure tolerance test due to contraction deformity of the non-coronary cusp at the end of 6 months (actually 30 months) in the largest 23 mm group. 4. Histopathologic observation was focussed in three view points, endothelial cell lining, collagen and elastic fiber destructions in each preservation methods and long durable valvular tolerance test group. Endothel ial cell lining and collagen fiber were well preserved in the glutaraldehyde and formaldehyde treated group with minimal destruction of elastic fiber. In long durable tolerance test group revealed complete destruction of the endothelial cell lining with minimal destruction of the collagen and elastic fiber in 3 month and 6 month group in relation to the time and severity. In conclusion, porcine xenograft treated after the proposal of Carpentier in 1972 and preserved in the glutaraldehyde solution was the best method of collection, preservation and valve mounting. Pressure tolerance and valve motion tolerance test, also, revealed most satisfactory results in the glutaraldehyde preserved group.

• The Korean Journal of Pesticide Science
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• v.18 no.4
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• pp.247-257
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• 2014

Assessment for operator's dermal and inhalation exposure to acetamiprid during cultivation of water melon in greenhouse was carried out. For dermal exposure measurement, whole body dosimetry (WBD) was performed as the first trial in Korea. WBD consists of cotton/polyester outer clothes and cotton inner clothes. Hand exposure was measured by washing of nitrile gloves and hands while head exposure was monitored by face/neck wipe technique. Inhalation exposure was monitored with personal air sampling pumps and IOM sampler (glass fiber filter). Analytical limit of quantitation was 2.5 ng/mL. Good reproducibility (C.V < 8.7%), linearity ($R^2$ > 0.99) and recovery (70~119%) were obtained. Field recovery of acetamiprid was 77~95%. During mixing/loading, hand exposure of acetamiprid was about 10 times ($229.7{\mu}g$) more than that of application case ($20.9{\mu}g$). During application, total dermal exposure was $1207.4{\mu}g$. Exposure of lower legs was $1132.1{\mu}g$, which is 93.8% of the total dermal exposure. Inhalation exposure during mixing/loading and application was not detected. Margin of safety (MOS) was calculated for risk assessment using male Korean average body weight (70 kg) and acceptable operator exposure level ($124{\mu}g/kg/day$) to give 140, suggesting that health risk of operator during treatment of acetamiprid for water melon in greenhouse could be safe.

• The Journal of Korean Society for Radiation Therapy
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• v.20 no.1
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• pp.17-23
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• 2008

Purpose: Cone-beam CT using linear accelerator attached to on-board imager is a image guided therapy equipment. Because it is to check the patient's set-up error, correction, organ and target movement. but imaging dose should be cause of the secondary cancer when taking a image. The aim of this study is investigation of appropriate cone beam CT scan mode to compare and estimate the image quality and skin dose. Materials and Methods: Measurement by Thermoluminescence dosimeter (TLD-100, Harshaw) with using the Rando phantom are placed on each eight sites in seperately H&N, thoracic, abdominal section. each 4 methods of scan modes of are measured the for skin dose in three time. Subsequently, obtained average value. Following image quality QA protocol of equipment manufacturers using the catphan 504 phantom, image quality of each scan mode is compared and analyzed. Results: The results of the measured skin dose are described in here. The skin dose of Head & Neck are measured mode A: 8.96 cGy, mode B: 4.59 cGy, mode C: 3.46 cGy mode D: 1.76 cGy and thoracic mode A: 9.42 cGy, mode B: 4.58 cGy, mode C: 3.65 cGy, mode D: 1.85 cGy, and abdominal mode A: 9.97 cGy, mode B: 5.12 cGy, mode C: 4.03 cGy, mode D: 2.21 cGy. Approximately, dose of mode B are reduced 50%, mode C are reduced 60%, mode D are reduced 80% a point of reference dose of mode A. the results of analyzed HU reproducibility, low contrast resolution, spatial resolution (high contrast resolution), HU uniformity in evaluation item of image quality are within the tolerance value by recommended equipment manufacturer in all scan mode. Conclusion: Maintaining the image quality as well as reducing the image dose are very important in cone beam CT. In the result of this study, we are considered when to take mode A when interested in soft tissue. And we are considered to take mode D when interested in bone scan and we are considered to take mode B, C when standard scan. Increasing secondary cancer risk due to cone beam CT scan should be reduced by low mAs technique.

• Journal of Yeungnam Medical Science
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• v.13 no.2
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• pp.279-294
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• 1996

This study was carried out to develop a Korean language version of Zung's self-rating anxiety scale(SAS) from august, 1994 to September, 1996. The subjects consisted of 205 normal control subjects from the general population group, and 97 subjects with anxiety disorders. These 97 subjects were chosen from a group by the structured clinical interview for DSM-IV of in patients and out patients. Both normal control subjects and anxiety disorder subjects were drawn utilizing a cluster of sampling methods. In order to analyze the data on anxiety scores, Pearson's product moment correlation coefficient method was carried out, as well as reliability, factor analysis and discriminant function analysis, utilizing the SPSS/PC+ program. The results obtained were as follows: The mean average of the total anxiety scores were 32.36 + 6.35 for the normal control subjects and 50.53 + 7.67 for anxiety disorder subjects. Test-retest reliability(coefficient r=0.98, p < 0.001), and internal consistency(coefficient r=0.96, p < 0.001) were satisfactory. Factor analysis using oblique technique rotation yielded four factors. The normal control subjects scored higher concerning the symptoms such as sweating, restlessness, apprehension, insomnia and dyspnea, and lower for faintness, mental disintegration, paresthesia, dizziness and tremor. On the other hand, for the anxiety disorders, apprehension, restlessness, sweating, dyspnea and insomnia scored higher, and lower for faintness, paresthesia, nightmare, dizziness and tremor.

• Journal of radiological science and technology
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• v.26 no.2
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• pp.57-61
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• 2003

The purpose of this study is to compare both 1.5T and 4.7T in Praietal White matter material Phantom using the same methodology at both field strengths. Data at both field strengths are compared in terms of $T_2$ relaxation times, line widths and SNRs MR imaging and $^1H$ MR spectroscopy were performed on GE 1.5T SIGNA system and Broker Biospec 4.7T/30 MRI/MRS system. After phantom axial scan $^1H$ MRS was obtained from T2 weighted image by 3-dimensional localization technique(PRESS : Point RE solved spectroscopy Sequence) this phantom is composed of an aqueous solution 36.7 mmol/L of NAA, 25.0 mmol/L of Cr, 6.3 mmol/L of choline chloride, 30.0 mmol/L or Glu, and 22.5 mmol/L of MI(adjusted to a pH of 7,15 in a phosphate buffet). Data processed using software developed inhouse. At 1.5T, T2 relaxation times for Cho, Cr, and NAA were $0.41{\pm}0.07,\;0.26{\pm}0.04,\;0.46{\pm}0.07$ while at 4.7T they were $0.17{\pm}0.03,\;0.14{\pm}0.05,\;0.20{\pm}0.03$ respectively. At 1.5T, line widths for water, Cho, Cr and NAA were $2.9{\pm}0.7,\;1.6{\pm}0.7,\;1.7{\pm}0.8,\;2.2{\pm}0.02Hz$ while at 4.7T they were $5.2{\pm}1.1,\;4.6{\pm}1.9,\;4.01{\pm}1.8,\;4.8{\pm}1.9Hz$ respectively. It can be seen that $T_2$ relaxation times were significantly shorter at 4.7 compared to 1.5T and that the line widths were also broader. The average SNRs for NAA for subjects at short and long TEs were $23.5{\pm}11.3$ at TE=20 msec ; $15.4{\pm}7.7$ at TE=272 msec at 1.5T and $40{\pm}8.3$ and $17{\pm}3.5$ respectively at 4.7T higher field strength is superior because of improved sensitivity and chemical shift dispersion. However these improvements are partially offset by increased line widths and decrease $T_2$ relaxation times, which act to reduce both sensitivity and resolution. In our experiments with the equipment available to us, 4.7T proton spectra at short TEs exhibit moderately improved sensitivity compared to 1.5T.

• Journal of radiological science and technology
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• v.32 no.1
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• pp.95-99
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• 2009

The purpose of this research is to seek SPAIR's reversal time (TI) which satisfies two conditions ; maintaining the suppression ability of fat tissue and simultaneously minimizing the inhomogeneity of fat tissue in T2 high-speed spin echo 3.0T magnetic resonance image (MRI) of the brain, and to compare SPAIR with STIR which is fat-suppression technique. The reversal times (TI) of SPAIR protocol are set to 1/2, 1/3, 1/6 and 1/12 of SPAIR TR (420 msec), namely 210 msec (8 people), 140 msec (26 people), 70 msec (26 people) and 35 msec (18 people) and STIR TI is set with 250 msec (26 people). With these parameter sets, we acquired the axis direction 104 images of the brain. In ROI ($50\;mm^2$) of output image, signal intensities of the fatty tissue, the muscular tissue, and the background were measured and the CNRs of fatty tissue and the muscular tissue were calculated. The inhomogeneity of the fatty tissue is SD/mean, where SD is the standard deviation and 'mean' is a average fatty tissue signal. Consequently, SPAIR TI is determined on either 1/3 or 1/6 of TR (420 ms) ; 140 ms or 70 ms. Because the difference of statistics in fat-suppression ability and inhomogeneity of fatty tissue is very small (p < 0.001), Selecting 140 ms seems to be better choice for the image quality. Meanwhile, Comparing SPAIR (TI : 140 ms) with STIR, the fat-suppression is not able to be considered statistically (p < 0.252), but the image quality is able to be considered statistically (p < 0.01). In conclusion, SPAIR is better than STIR in the image quality.

• Nuclear Engineering and Technology
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• v.25 no.2
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• pp.237-247
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• 1993

Activity ratio of two radioactive primary fission products which had sufficiently different half-lives was expressed as functions of cooling time and irradiation histories in which average burnup, irradiation time, cycle interval time and the dominant fissile material of the spent fuel were included. The gamma-ray spectra of 36 samples from 6 spent PWR fuel assemblies irradiated in Kori unit-1 reactor were obtained by a spectrometric system equipped with a high purity germanium gamma-ray detector. Activity ratio $^{l44}$Ce $^{l37}$Cs, analyzed from each spectrum, was used for the calculation of cooling time. The results show that the radioactive fission products $^{l44}$Ce and $^{l37}$Cs are considered as useful monitors for cooling time determination because the estimated cooling time by detection of activity ratio $^{l44}$Ce $^{l37}$Cs agreed well with the operator declared cooling time within relative difference of $\pm$5 % despite the low counting rate of the gamma-ray of $^{l44}$Ce (about 10$^{-3}$ count per second). For the samples with several different irradiation histories, the determined cooling time by modeled irradiation history showed good agreement with that by known irradiation history within time difference of $\pm$0.5 year. From this result, it would be expected to be possible to estimate reliably the cooling time of spent nuclear fuel without the exact information about irradiation history. The feasibility study on identification of and/or sorting out spent nuclear fuel by applying the technique for cooling time determination was also performed and the result shows that the detection of activity ratio $^{l44}$Ce $^{l37}$Cs by gamma-ray spectrometry would be usefully applicable to certify spent nuclear fuel for the purpose of safeguards and management in a facility in which the samples dismantled or cut from spent fuel assemblies are treated, such as the post irradiation examination facility.mination facility.

• Korean Journal of Soil Science and Fertilizer
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• v.26 no.1
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• pp.43-48
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• 1993

A laboratory study was cunducted to obtain fundamental informations on environmental-conservative treatment technique of soiled animalwaste. The release rate of inorganic nitrogen which mineralized from solid pigwaste and the effect of nitrification inhibitor(Dicyandiamide, DCD) on nitrate concentration of fresh or fermented pigwaste were weekly checked for ten weeks under incubation condition. Average pH of soild pigwaste was maintained over 8 unit during all incubation periods with no difference by nitrification inhibitor addition and the pHs of fresh- or fermented pigwaste without DCD were elevated by passing time 0.04, 0.058 pH unit/week (P<0.05) during incubation. While $NH_4-N$ concentration of fermented pigwaste until two week was nearly the same as it before incubation, $NH_4-N$ concentration of fresh pigwaste was remarkably increased upto 3,732 ppm for 1 week after incubation and the portion of increased $NH_4-N$ concentration, 2,473 ppm was 20.1% of indigenous organic nitrogen of fresh pigwaste. By the passing incubation time, $NH_4-N$ concentration began to lower linearly at not only fresh- but fermented pigwaste after 1 or 2 week, respectively and the $NH_4-N$ concentration loss rate at fresh pigwaste was 61.8 ppm/week with DCD addition and 72.3ppm/week with no DCD. There was positive relationship between $NO_3-N$ concentrations of fresh pigwaste by the addition of DCD or not and $NO_3-N$ concentraion was significantly lowered with DCD treatment($r=0.79^{**}$).