• Progress in Medical Physics
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• v.25 no.4
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• pp.218-224
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• 2014

The small field dosimetry is very important in modern radiotherapy because it has been frequently used to treat the tumor with high dose hypo-fractionated radiotherapy or high dose single fraction stereotactic radiosurgery (SRS) with small size target. But, the dosimetry of a small field (< $3{\times}3cm^2$) has been great challenges in radiotherapy. Small field dosimetry is difficult because of (a) a lack of lateral electronic equilibrium, (b) steep dose gradients, and (c) partial blocking of the source. The objectives of this study were to measure and verify with the various detectors the output factors in a small field (<3 cm) for the 6 MV photon beams. Output factors were measured using the CC13, CC01, EDGE detector, thermoluminescence dosimeters (TLDs), and Gafchromic EBT2 films at the sizes of field such as $0.5{\times}0.5$, $1{\times}1$, $2{\times}2$, $3{\times}3$, $5{\times}5$, and $10{\times}10cm^2$. The differences in the output factors with the various detectors increased with decreasing field size. Our study demonstrates that the dosimetry for a small photon beam (< $3{\times}3cm^2$) should use CC01 or EDGE detectors with a small active volume. And also, Output factors with the EDGE detectors in a small field (< $3{\times}3cm^2$) coincided well with the Gafchromic EBT2 films.

• Journal of the Society of Cosmetic Scientists of Korea
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• v.30 no.3 s.47
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• pp.353-359
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• 2004

The extent of silica flocculation can be modified by varying the silica concentration, aqueous phase pH, salt and polvmer concentration. High volume fraction W/O emulsion stabilized by hydrophobic silica was established with various aqueous phase conditions for cosmetic application. By increasing the silica concentration up to $1.0\;wt\%,$ the size of droplet decreased. A high silica concentration increased the viscosity of continuous oil phase by network formation, which resulted in target size of droplet. The stability of W/O emulsion is improved as increasing the aqueous phase pH. At low and intermediate pH, the emulsions became more stable by adding salt $(0.083\;mol\;dm^{-3}\;MgSO_4).$ At high PH, the presence of salt caused significant destabilization. The gelation behavior of the emulsion indicates that the effect of salt on silica-stabilized emulsion is derived from an electrostatic attraction. The addition of xanthan gum in aqueous phase increased the mono-dispersity of the W/O emulsion by making water more hydrophobic and hindering the recombination of droplets. In conclusion, these results indicate that very stable emulsifier-free, finely dispersed W/O emulsion can be achieved for cosmetic application by changing the aqueous phase composition.

• Journal of the Korean Society of Radiology
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• v.16 no.5
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• pp.567-574
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• 2022

Coronary artery disease (CAD) and atrial fibrillation (AF) are known to share many risk factors. In particular, in the case of acute coronary syndrome, it may be difficult to clearly determine the diameter of the vessel due to complete occlusion of the vessel and thrombus. Thus, the relationship between the diameter of the coronary arteries was evaluated to be used as a reference data before the treatment of coronary arteries and drug selection in patients with AF. From January 2020 to August 2022, images of coronary angiography (CAG) with AF and normal sinus rhythm (NSR) on electrocardiography were target. In both subjects, images of normal coronary artery without lesions as a result of CAG were used. For all vessels, the diameters of the vessels were measured by dividing them into proximal, middle, and distal parts, and the measured diameters were divided by the average for evaluation. As a result of analyzing the left anterior descending artery diameter, the vessel diameter of the AF patient was 2.24±0.26 mm, which was smaller than that of the NSR patient, 2.86±0.38 mm, and was statistically significant. (p<0.001) As a result of analyzing the left circumflex artery diameter, the vessel diameter of the AF patient was 2.34±0.28 mm, which was smaller than the vessel diameter of the NSR patient, 2.87±0.29 mm, and was statistically significant. (p<0.001) As a result of analyzing the diameter of the right coronary artery, the vessel diameter of the AF patient was 2.68±0.5 mm, which was smaller than the vessel diameter of the NSR patient, 3.35±0.4 mm, and was statistically significant. (p<0.001) Considering that the coronary artery size of AF patients is significantly smaller than the coronary vessel size of NSR patients, it is considered as a useful study to be used as a reference for evaluating coronary artery diameter when the arrhythmia is AF. In particular, it is considered to be a study that can be helpful in diagnosing lesions, using drugs before and after surgery, and choosing to use auxiliary devices such as intravascular ultrasound.

• Journal of agriculture & life science
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• v.50 no.1
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• pp.273-281
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• 2016

In this study, after carrying out a bending test that targeted the frames of plastic film greenhouse, the load-displacement relationship was analyzed to be used as basic data to develop greenhouse construction and maintenance guidelines. As a result, regardless of the shapes of the specimen, the yield and the maximum load increased as the size of the specimen increased. The displacement also showed the same pattern. A steel pipe showed lower yield and maximum load than a square pipe, and the displacement was large. In the steel pipe case, the displacement under the yield and maximum load was in the range of approximately 1.42-4.20mm and 5.80-24.13mm, respectively. In the square pipe case, the displacement under the yield and maximum load was in the range of approximately 1.62-3.00mm and 3.13-8.01mm, respectively. Further, a large difference was observed between the result of this test and the values calculated by a conventionally provided standard. In particular, not much difference was found from the result of this test in the case of a purlin member from the values provided by previous researches. However, a large difference was observed in the column or main rafter members. Furthermore, when a wide-span and venlo type, which is a glasshouse, was used as a target(h/100 and h/80), the displacement under the yield and maximum load was approximately 28.0mm and 35.0mm, respectively, which showed a large difference compared with the Netherlands standard(14.0mm) of a glasshouse. Further, in the main rafter case, a large difference was observed in the displacement limit according to the width(i.e., span) of the greenhouse where members are used. Therefore, because the displacement limit can vary depending on various factors such as type, form, and size of a greenhouse, we determined that studies or tests that consider these factors should be carried out to reflect them in the construction and maintenance of greenhouses.

• Journal of Intelligence and Information Systems
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• v.28 no.1
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• pp.107-129
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• 2022

It is important to preempt new technology because the technology competition is getting much tougher. Stakeholders conduct exploration activities continuously for new technology preoccupancy at the right time. Gartner's Hype Cycle has significant implications for stakeholders. The Hype Cycle is a expectation graph for new technologies which is combining the technology life cycle (S-curve) with the Hype Level. Stakeholders such as R&D investor, CTO(Chef of Technology Officer) and technical personnel are very interested in Gartner's Hype Cycle for new technologies. Because high expectation for new technologies can bring opportunities to maintain investment by securing the legitimacy of R&D investment. However, contrary to the high interest of the industry, the preceding researches faced with limitations aspect of empirical method and source data(news, academic papers, search traffic, patent etc.). In this study, we focused on two research questions. The first research question was 'Is there a difference in the characteristics of the network structure at each stage of the hype cycle?'. To confirm the first research question, the structural characteristics of each stage were confirmed through the component cohesion size. The second research question is 'Is there a pattern of diffusion at each stage of the hype cycle?'. This research question was to be solved through centralization index and network density. The centralization index is a concept of variance, and a higher centralization index means that a small number of nodes are centered in the network. Concentration of a small number of nodes means a star network structure. In the network structure, the star network structure is a centralized structure and shows better diffusion performance than a decentralized network (circle structure). Because the nodes which are the center of information transfer can judge useful information and deliver it to other nodes the fastest. So we confirmed the out-degree centralization index and in-degree centralization index for each stage. For this purpose, we confirmed the structural features of the community and the expectation diffusion patterns using Social Network Serice(SNS) data in 'Gartner Hype Cycle for Artificial Intelligence, 2021'. Twitter data for 30 technologies (excluding four technologies) listed in 'Gartner Hype Cycle for Artificial Intelligence, 2021' were analyzed. Analysis was performed using R program (4.1.1 ver) and Cyram Netminer. From October 31, 2021 to November 9, 2021, 6,766 tweets were searched through the Twitter API, and converting the relationship user's tweet(Source) and user's retweets (Target). As a result, 4,124 edgelists were analyzed. As a reult of the study, we confirmed the structural features and diffusion patterns through analyze the component cohesion size and degree centralization and density. Through this study, we confirmed that the groups of each stage increased number of components as time passed and the density decreased. Also 'Innovation Trigger' which is a group interested in new technologies as a early adopter in the innovation diffusion theory had high out-degree centralization index and the others had higher in-degree centralization index than out-degree. It can be inferred that 'Innovation Trigger' group has the biggest influence, and the diffusion will gradually slow down from the subsequent groups. In this study, network analysis was conducted using social network service data unlike methods of the precedent researches. This is significant in that it provided an idea to expand the method of analysis when analyzing Gartner's hype cycle in the future. In addition, the fact that the innovation diffusion theory was applied to the Gartner's hype cycle's stage in artificial intelligence can be evaluated positively because the Gartner hype cycle has been repeatedly discussed as a theoretical weakness. Also it is expected that this study will provide a new perspective on decision-making on technology investment to stakeholdes.

• Journal of Radiation Protection and Research
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• v.32 no.3
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• pp.105-110
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• 2007

Purpose : In spite of recent remarkable improvement of diagnostic imaging modalities such as CT, MRI, and PET and radiation therapy planing systems, ICR plan of uterine cervix cancer, based on recommendation of ICRU38(2D film-based) such as Point A, is still used widely. A 3-dimensional ICR plan based on CT image provides dose-volume histogram(DVH) information of the tumor and normal tissue. In this study, we compared tumor-dose, rectal-dose and bladder-dose through an analysis of DVH between CTV plan and ICRU38 plan based on CT image. Method and Material : We analyzed 11 patients with a cervix cancer who received the ICR of Ir-192 HDR. After 40Gy of external beam radiation therapy, ICR plan was established using PLATO(Nucletron) v.14.2 planing system. CT scan was done to all the patients using CT-simulator(Ultra Z, Philips). We contoured CTV, rectum and bladder on the CT image and established CTV plan which delivers the 100% dose to CTV and ICRU plan which delivers the 100% dose to the point A. Result : The volume$(average{\pm}SD)$ of CTV, rectum and bladder in all of 11 patients is $21.8{\pm}6.6cm^3,\;60.9{\pm}25.0cm^3,\;111.6{\pm}40.1cm^3$ respectively. The volume covered by 100% isodose curve is $126.7{\pm}18.9cm^3$ in ICRU plan and $98.2{\pm}74.5cm^3$ in CTV plan(p=0.0001), respectively. In (On) ICRU planning, $22.0cm^3$ of CTV volume was not covered by 100% isodose curve in one patient whose residual tumor size is greater than 4cm, while more than 100% dose was irradiated unnecessarily to the normal organ of $62.2{\pm}4.8cm^3$ other than the tumor in the remaining 10 patients with a residual tumor less than 4cm in size. Bladder dose recommended by ICRU 38 was $90.1{\pm}21.3%$ and $68.7{\pm}26.6%$ in ICRU plan and in CTV plan respectively(p=0.001) while rectal dose recommended by ICRU 38 was $86.4{\pm}18.3%$ and $76.9{\pm}15.6%$ in ICRU plan and in CTV plan, respectively(p=0.08). Bladder and rectum maximum dose was $137.2{\pm}50.1%,\;101.1{\pm}41.8%$ in ICRU plan and $107.6{\pm}47.9%,\;86.9{\pm}30.8%$ in CTV plan, respectively. Therefore, the radiation dose to normal organ was lower in CTV plan than in ICRU plan. But the normal tissue dose was remarkably higher than a recommended dose in CTV plan in one patient whose residual tumor size was greater than 4cm. The volume of rectum receiving more than 80% isodose (V80rec) was $1.8{\pm}2.4cm^3$ in ICRU plan and $0.7{\pm}1.0cm^3$ in CTV plan(p=0.02). The volume of bladder receiving more than 80% isodose(V80bla) was $12.2{\pm}8.9cm^3$ in ICRU plan and $3.5{\pm}4.1cm^3$ in CTV plan(p=0.005). According to these parameters, CTV plan could also save more normal tissue compared to ICRU38 plan. Conclusion : An unnecessary excessive radiation dose is irradiated to normal tissues within 100% isodose area in the traditional ICRU plan in case of a small size of cervix cancer, but if we use CTV plan based on CT image, the normal tissue dose could be reduced remarkably without a compromise of tumor dose. However, in a large tumor case, we need more research on an effective 3D-planing to reduce the normal tissue dose.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.37 no.3
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• pp.196-213
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• 2001

A split beam ultrasonic transducer operating at a frequency of 70 kHz to use in the fish sizing echo sounder was developed and the acoustic radiation characteristics were experimentally analyzed. The amplitude shading method utilizing the properties of the Chebyshev polynomials was used to obtain side lobe levels below -20 dB and to optimize the relationship between main beam width and side lobe level of the transducer, and the amplitude shading coefficient to each of the elements was achieved by changing the amplitude contribution of elements with 4 weighting transformers embodied in the planar array transducer assembly. The planar array split beam transducer assembly was composed of 36 piezoelectric ceramics (NEPEC N-21, Tokin) of rod type of 10 mm in diameter and 18.7 mm in length of 70 kHz arranged in the rectangular configuration, and the 4 electrical inputs were supplied to the beamformer. A series of impedance measurements were conducted to check the uniformity of the individual quadrants, and also in the configurations of reception and transmission, resonant frequency, and the transmitting and receiving characteristics were measured in the water tank and analyzed, respectively. The results obtained are summarized as follows : 1. Average resonant and antiresonant frequencies of electrical impedance for four quadrants of the split beam transducer in water were 69.8 kHz and 83.0 kHz, respectively. Average electrical impedance for each individual transducer quadrant was 49.2$\Omega$ at resonant frequency and 704.7$\Omega$ at antiresonant frequency. 2. The resonance peak in the transmitting voltage response (TVR) for four quadrants of the split beam transducer was observed all at 70.0 kHz and the value of TVR was all about 165.5 dB re 1 $\mu$Pa/V at 1 m at 70.0 kHz with bandwidth of 10.0 kHz between -3 dB down points. The resonance peak in the receiving sensitivity (SRT) for four combined quadrants (quad LU+LL, quad RU+RL, quad LU+RU, quad LL+RL) of the split beam transducer was observed all at 75.0 kHz and the value of SRT was all about -177.7 dB re 1 V/$\mu$Pa at 75.0 kHz with bandwidth of 10.0 kHz between -3 dB down points. The sum beam transmitting voltage response and receiving senstivity was 175.0 dB re 1$\mu$Pa/V at 1 m at 75.0 kHz with bandwidth of 10.0 kHz, respectively. 3. The sum beam of split beam transducer was approximately circular with a half beam angle of $9.0^\circ$ at -3 dB points all in both axis of the horizontal plane and the vertical plane. The first measured side lobe levels for the sum beam of split beam transducer were -19.7 dB at $22^\circ$ and -19.4 dB at $-26^\circ$ in the horizontal plane, respectively and -20.1 dB at $22^\circ$ and -22.0 dB at $-26^\circ$ in the vertical plane, respectively. 4. The developed split beam transducer was tested to estimate the angular position of the target in the beam through split beam phase measurements, and the beam pattern loss for target strength corrections was measured and analyzed.

• Journal of Chest Surgery
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• v.37 no.10
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• pp.845-855
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• 2004

Background: No general consensus has been available regarding the necessity of postoperative radiation therapy (PORT) and its optimal techniques in the patients with chest wall invasion (pT3cw) and node negative (N0) non-small cell lung cancer (NSCLC). We did retrospective analyses on the pT3cwN0 NSCLC patients who received PORT because of presumed inadequate resection margin on surgical findings. And we compared them with the pT3cwN0 NSCLC patients who did not received PORT during the same period. Material and Method: From Aug. of 1994 till June of 2002, 22 pT3cwN0 NSCLC patients received PORT-PORT (＋) group- and 16 pT3cwN0 NSCLC patients had no PORT-PORT (-) group. The radiation target volume for PORT (＋) group was confined to the tumor bed plus the immediate adjacent tissue only, and no regional lymphatics were included. The prognostic factors for all patients were analyzed and survival rates, failure patterns were compared with two groups. Result: Age, tumor size, depth of chest wall invasion, postoperative mobidities were greater in PORT (-) group than PORT (＋) group. In PORT (-) group, four patients who were consulted for PORT did not receive the PORT because of self refusal (3 patients) and delay in the wound repair (1 patient). For all patients, overall survival (OS), disease-free survival (DFS), loco-regional recurrence-free survival (LRFS), and distant metastases-free survival (DMFS) rates at 5 years were 35.3%, 30.3%, 80.9%, 36.3%. In univariate and multivariate analysis, only PORT significantly affect the survival. The 5 year as rates were 43.3% in the PORT (＋) group and 25.0% in PORT (-) group (p=0.03). DFS, LRFS, DMFS rates were 36.9%, 84.9%, 43.1 % in PORT (＋) group and 18.8%, 79.4%, 21.9% in PORT(-) group respectively. Three patients in PORT (-) group died of intercurrent disease without the evidence of recurrence. Few suffered from acute and late radiation side effects, all of which were RTOG grade 2 or lower. Conclusion: The strategy of adding PORT to surgery to improve the probability not only of local control but also of survival could be justified, considering that local control was the most important component in the successful treatment of pT3cw NSCLC patients, especially when the resection margin was not adequate. Authors were successful in the marked reduction of the incidence as well as the severity of the acute and late side effects of PORT, without taking too high risk of the regional failures by eliminating the regional lymphatics from the radiation target volume.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.32 no.6
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• pp.737-747
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• 1999

To estimate biomass and distribution of the Antarctic krill (Euphausia superba), hydroacoustic survey was conducted on board of R/V Yuzhmorgeologiya, which was chartered by Korea Antarctic Research Program (KARP) group from 18 to 21 December 1998, in the northern part of the South Shetland Islands, Antarctic Ocean, The scientific echo sounder (towing body type) used was EK- 500 (SIMRAD, Norway) with echo integrator (BI-500) at 38 kHz frequency and recorded mean backscattering cross-section coefficient (SA) per 1 $mile^2$ of sea surface. Also, Bongo net sampling was carried out to determine the size of krill and CTD (Conductivity, Temperature and Depth) casting to understand physical structure. Water column was divided into 5 layers (22$\~$65 m, 65$\~$115 m, l15$\~$65 m, 165$\~$215 m and 215$\~$315 m) to know vertical distribution of krill biomass. The standard length of krill collected was between 30 mm and 51 mm, and adult krill had single mode (41 mm). Maximum horizontal length of krill patch was about 35 nautical mile and vertical thickness was about 275 m. High density of krill was appeared in frontal area between Circumpolar Deep Water (>$1^{\circ}C$) and very low temperature water mass (< $-0.5^{\circ}C$) that originate from Weddell Sea. According to the results calculated using target strength equation, krill density was totally higher in continental slope and open water areas than in coastal area. In the study area, krill seems to distribute in depth; density was low at first layer ($\={\rho}=17.0\;g/m^2$) and higher at fourth layer ($\={\rho}=40.19\;g/m^2$). The estimated krill biomass at total survey area and water column was about 2.77 million metric ion ($\={\rho}=151.0\;g/m^2$) and coefficient of valiance ( CV, $\%$) was 19.92. The proportions and biomass of krill biomass at each layer were as follows; layer 1 ($11.3\%$, 0.31 million metric ton, CV=16.24), layer 2 ($13.3\%$, 0.37 million metric ton, CV=34.91), layer 3 ($23.7\%$, 0.66 million metric ton, CV=41.5), layer 4 ($26.6\%$, 0.74 million metric ton, CV=27.84) and layer 5 ($25\%$, 0.69 million metric ton, CV= 26.83).

• The Journal of Korean Society for Radiation Therapy
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• v.32
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• pp.93-109
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• 2020

Purpose: The radiochromic film (Gafchromic EBT3, Ashland Advanced Materials, USA) and 3-dimensional analysis system dosimetry checkTM (DC, MathResolutions, USA) were evaluated for patient-specific quality assurance (QA) of helical tomotherapy. Materials and Methods: Depending on the tumors' positions, three types of targets, which are the abdominal tumor (130.6㎤), retroperitoneal tumor (849.0㎤), and the whole abdominal metastasis tumor (3131.0㎤) applied to the humanoid phantom (Anderson Rando Phantom, USA). We established a total of 12 comparative treatment plans by the four geometric conditions of the beam irradiation, which are the different field widths (FW) of 2.5-cm, 5.0-cm, and pitches of 0.287, 0.43. Ionization measurements (1D) with EBT3 by inserting the cheese phantom (2D) were compared to DC measurements of the 3D dose reconstruction on CT images from beam fluence log information. For the clinical feasibility evaluation of the DC, dose reconstruction has been performed using the same cheese phantom with the EBT3 method. Recalculated dose distributions revealed the dose error information during the actual irradiation on the same CT images quantitatively compared to the treatment plan. The Thread effect, which might appear in the Helical Tomotherapy, was analyzed by ripple amplitude (%). We also performed gamma index analysis (DD: 3mm/ DTA: 3%, pass threshold limit: 95%) for pattern check of the dose distribution. Results: Ripple amplitude measurement resulted in the highest average of 23.1% in the peritoneum tumor. In the radiochromic film analysis, the absolute dose was on average 0.9±0.4%, and gamma index analysis was on average 96.4±2.2% (Passing rate: >95%), which could be limited to the large target sizes such as the whole abdominal metastasis tumor. In the DC analysis with the humanoid phantom for FW of 5.0-cm, the three regions' average was 91.8±6.4% in the 2D and 3D plan. The three planes (axial, coronal, and sagittal) and dose profile could be analyzed with the entire peritoneum tumor and the whole abdominal metastasis target, with planned dose distributions. The dose errors based on the dose-volume histogram in the DC evaluations increased depending on FW and pitch. Conclusion: The DC method could implement a dose error analysis on the 3D patient image data by the measured beam fluence log information only without any dosimetry tools for patient-specific quality assurance. Also, there may be no limit to apply for the tumor location and size; therefore, the DC could be useful in patient-specific QAl during the treatment of Helical Tomotherapy of large and irregular tumors.