• Radiation Oncology Journal
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• v.18 no.3
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• pp.194-199
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• 2000

Purpose : Then determining the lower margin of post-operative pelvic radiation therapy field according to the traditional method (recommended by Gunderson), the organs located in the low pelvic cavity and the perineum are vulnerable to unnecessary radiation. This study evaluated the effect of individualized determination of the lower margin at 2 cm to 3 cm below the anastomotic site on the failure patterns. Materials and Methods . Authors included ぉ patients with modified Astler-Coiler (MAC) stages from B2 through C3, who received low anterior resection and post-operative pelvic radiation therapy from Sept. 1994 to May 1998 at Samsung Medical Center, Sungkyunkwan University. The numbers of male and female patients were 44 and 44, and the median age was 57 years (range: 32-81 years). Three field technique (posterior-anterior and bilateral portals) by 6, 10, 15 MV X-rays was used to deliver 4,500 cGy to the whole pelvis followed by Sn cGy's small field boost to the tumor bed over 5.5 weeks. Sixteen patients received radiation therapy by traditional field margin determination, and the lower margin was set either at the low margin of the obturator foramen or at 2 cm to 3 cm below the anastomotic site, whichever is lower. In 72 patients, the lower margin was set at 2 cm to 3 cm below the anastomotic site, irrespectively of the obturator foramen, by which the reduction of radiation volume was possible in 55 patients ($76\%$). Authors evaluated and compared survival, local control, and disease-free survival rates of these two groups. Results : The median follow-up period was 27 months (range : 7-58 months). MAC stages B2 in 32($36\%$), B3 in 2 ($2\%$), Cl in 2 ($2\%$), C2 in 50 ($57\%$), and C3 in 2 ($2\%$) Patients, respectively. The entire patients' overall survival rates at 2 and 4 years were $94\%$ and $68\%$, respectively, and disease-free survival rates at 2 and 4 years were $86\%$ and $58\%$, respectively. The first failure sites were local only in 4, distant only in 14, and combined local and distant in 1 patient, respectively. There was no significant difference with respect to local control and disease-free survival rates ( p=0.42, p=0.68) between two groups of different lower margin determination policies. Conclusion : The new concept in the individualized determination of the lower margin depending on the anastomotic site has led to the equivalent local control and disease-free survival rates, and is expected to contribute to the reduction of unnecessary radiation-related morbidity by reduction of radiation volume, compared with the traditional method of lower margin determination.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.02a
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• pp.180-180
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• 2013

반도체, 디스플레이와 같이 저압, 극청정 조건에서 진행되는 공정에서 발생한 오염입자는 수 율에 큰 영향을 미친다. 따라서 공정 중에 발생한 오염입자를 실시간으로 모니터링할 수 있는 장비에 대한 연구가 활발히 진행되고 있다. Particle Beam Mass Spectrometer (PBMS)는 저압에서 실시간으로 나노 입자의 크기를 측정할 수 있는 대표적인 장비 중 하나이다. 입자를 포함한 가스 유동이 PBMS로 유입되면, 우선 입자를 입자빔의 형태로 집속하는 공기역학렌즈를 통과하게 된다. 집속된 입자는 노즐에 의해서 가속되며, 이로 인해 충분한 관성을 가지게 된 입자는 양극과 음극, 필라멘트로 구성된 electron gun에서 전자충돌에 의해 포화상태로 하전된다. 하전한 입자는 electrostatic deflector에서 크기에 따라 분류되어 Faraday detector와 electrometer에 의해 측정된다. 그러나 공기역학렌즈는 입자의 크기가 작아질수록 집속 효율이 급격히 낮아진다는 문제점을 지니고 있다. 이는 입자가 작아질수록 점성에 의한 영향이 관성에 의한 영향보다 커짐으로써 나타나는 현상이다. 최근 이러한 문제점을 해결하기 위해 사중극자를 사용하여 입자를 집속시키는 방법이 대안으로 제시되었다. 사중극자는 서로 마주보는 쌍곡선 형태의 전극구조에 AC 전기장을 인가하는 방식을 사용한다. 사중극자의 중심은 정확히 평형점을 가지게 되며 입자는 사중극자 내에서 진동을 반복하며 평형점을 향해 모이게 된다. 입자의 크기가 작을수록 전기력에 의한 영향을 크게 받으므로 사중극자를 이용한 입자집속 방법은 나노입자의 집속에 있어 공기역학렌즈를 이용한 집속에 비해 이점을 지닌다. 또한 집속 하고자 하는 입자 대상이 바뀔 경우 구조를 바꿔야 하는 공기역학렌즈와 달리 사중극자를 이용한 방법은 AC 전기장을 조절하는 것 만으로 제어가 가능하다. 본 연구에서는 저압 조건에서 나노입자를 집속하기 위한 사중극자의 전극 구조를 이론적인 계산을 통하여 구하였다. 그 결과 0.1 torr의 압력 조건하에서 5~100 nm 범위의 기본 입자를 AC 전압과 진동수를 조절하여 집속할 수 있는 사중극자 형태를 설계하였다.

• Textile Coloration and Finishing
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• v.4 no.2
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• pp.84-88
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• 1992

셀룰로오스 펄프에 폴리비닐알코올의 블랜드, 가교, 및 카복시메칠화한 아니온성 셀룰로오스계 고분자 흡착제에 대한 모델 카치온 염료, C.I. Basic Red 18의 흡착 및 탈색 성능을 수용액계(pH 4.2)에서 검토하였다. 아니온성 셀룰로오스 고분자 흡착제의 카치온 모델 염료의 흡착등온성은 저농도 영역에서 Sigmoidal 형을 나타내었고 Donnan 흡착 모델 기구로 해석하였다. 하전기 도입에 따라 염료의 흡착능은 증가하였으며 이 흡착능력은 Sodium이온의 첨가에 의하여 저하하였다. 또 아니온 셀룰로오스계 흡착제에 의한 모델 염료의 배수 탈색율은 크게 증가하였으며 입상활성탄보다 우수한 탈색능력을 나타내었다.

• Proceedings of the Korean Nuclear Society Conference
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• 1998.05a
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• pp.157-162
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• 1998

양전자 단층 촬영장치(PET)에 사용되는 주요 양전자 방출 핵종들의 생성 단면적을 평가하였다. 평가한 생성 반응들은 $^{14}$ N(p,$\alpha$)$^{11}$ C,$^{16}$ O(p,$\alpha$)$^{13}$N, $^{14}$ N(d,n)$^{15}$ O,$^{18}$ O(p,n)$^{18}$ F,$^{20}$ Ne(d,$\alpha$)$_{18}$ F 이며, 입사 입자의 에너지 범위는 반응 문턱 에너지부터 약 150 MeV까지이다. 또한 하전입자 범 모니터용 표준 단면적으로서 $^{27}$ Al에 d 및 $^3$He, $\alpha$가 반응하여 $^{22}$ Na가 생성되는 반응의 단면적들을 입사 에너지 약 120 MeV까지 평가하였다. 실험치를 fitting하게나 ALICE95 코드를 이용하여 이론적 계산을 수행하였는데, 평가 단면적의 표준 편차는 10-30%이다 이들 평가 단면적들은 가속기를 이용한 PET용 핵종의 생산율 계산 및 빔 모니터의 표준 단면적으로 사용하기에 적절한 것으로 판단된다.

• Proceedings of the Korean Vacuum Society Conference
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• 2010.02a
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• pp.459-459
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• 2010

대면적 마그네트론 스퍼터링 캐소드를 이용하여 고효율 스퍼터링을 실현하기 위해서는 진공 상태에서 하전입자의 손실을 최소화하여 플라즈마 내에 많은 입자를 구속하는 기술이 요구된다. 본 연구에서는 고효율 특성을 갖는 대면적 캐소드($127mm{\times}900mm$) 설계를 위해 유한요소법(Finite Element Method) 수치해석 알고리즘을 이용한 3차원 전자장(Magnetostatic) 시뮬레이션 툴을 이용하여 최적화된 캐소드를 설계하였다. 캐소드 타겟 배면에 생성되는 자기장의 3차원 특성 해석을 통해 타겟효율에 가장 큰 영향을 미치는 자속밀도의 관계를 분석하였다. 고효율 캐소드 구조 설계를 위해서는 타겟 배면에 평행한 자속밀도의 분포를 최대한 확보를 것이 매우 중요하다. 이러한 특성을 확보하기 위하여 캐소드 내부에 장착되는 자석 크기 및 특성에 따른 자속밀도 특성을 해석하였다. 개발된 마그네트론 캐소드에 Si 타겟을 장착하였다. 캐소드 특성 평가를 위해 Ar 분위기 및 $O_2$를 동시에 인가하여 Si 및 $SiO_2$ 박막을 유리기판에 코팅하였다. 코팅된 박막의 특성 평가는 결정구조와 두께에 따른 투과율 및 반사율 측정을 수행하였다. Si 박막의 경우, 갈색의 코팅막을 형성하였으며, $SiO_2$의 경우, 투명한 박막으로 증착되었고 조성분석(EDXS)에 의해 $SiO_2$로 잘 코팅되었음을 확인할 수 있었다. 그리고, $SiO_2$가 코팅된 막의 투과율은 유리기판에 비해 1% 정도 향상되었음을 확인할 수 있었다. 마그네트론 캐소드 성능은 Si 타겟의 erosion 형상 분석과 3차원 유한요소법 프로그램을 이용한 자기장 분석을 통해 비교 분석하였다.

• Progress in Medical Physics
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• v.1 no.1
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• pp.97-107
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• 1990

A method of detecting charged particles in an allyl diglycol carbonate material (PN-3) which is available, amorphous, optically clear and thermoset plastic in which nuclear particle tracks could be revealed by etching in hot NaOH solutions, has been investigated. It has been applied to the study of alpha particle tracks over an energy range of 3.17～5.49 MeV which has been obtained after having passed through several sheets of polycarbonate. The dose equivalent rate of the alpha source was calculated and the spark chamber was used in order to measure the range of alpha particles after having passed through different number of absorbers. The etching characteristics and the detection response of PN-3 have been studied as a funcion of lengths of etched tracks against the parameters of energies and of the track etching rate(V$_{T}$). The investigation of the etching process for alpha particles in the PN-3 provided the most interesting results.s.

• Resources Recycling
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• v.13 no.1
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• pp.39-46
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• 2004

Triboelectrostatic separation process is a technology that different particles charged after contact and rubbing different materials are separated in a high electric field. This technology has an advantage in that it can be used for separating non-conducting materials such as plastics unlike other electrostatic separation processes. There are two objectives in this study. One is to develop an effective continuous tribo-electrostatic separation process. The other is to apply the developed device for the separation of mixed plastics. Results show that almost all tested plastics reaches over 95% in yield and grade after separation.

• Journal of Convergence for Information Technology
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• v.12 no.2
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• pp.127-133
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• 2022

Two types of charged particle-type electronic paper display panels with electrodes using ITO and CNT are fabricated to compare durability and electro-optical characteristics. The sheet resistance of the ITO electrode is 10 (ohm/sq.), and the sheet resistance of the CNT electrode is 300, 600, 1000 (ohm/sq.), and durability is carried out by impact and flexibility measurements. Variation in case of the ITO electrode begins at shocks of 40 times and curvature radius of 10 mm, and no change is observed in the CNT electrode. The driving voltage, electric field required for particle movement, reflectivity, and response time measurements show similar results for all ITO and CNT electrodes.

• Journal of the Korean Vacuum Society
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• v.7 no.4
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• pp.374-380
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• 1998

Radical and ion densities in a $CF_4$plasma have been calculated as a function of input power density, gas pressure and feed gas flow rate using simple 0 dimensional global model. Fluorine atom is found to be the most abundant neutral particle. Highly fragmented species such as CF and $CF^+$ become dominant neutral and ionic radical at the high power condition. As the pressure increase, ion density increases but ionization rate decreases due to the decrease in electron temperature. The fractional dissociation of $CF_4$feed gas decreases with pressure after increasing at the low pressure range. Electron density and temperature are almost independent of flow rate within calculation conditions studied. The fractional dissociation of $CF_4$monotonically decreases with flow rate, which results in increase in $CF_3$and decrease in CF density. The calculation results show that the $SiO_2$etch selectivity improvement correlates to the increase in the relative density of fluorocarbon ion and neutral radicals which has high C/F ratio.

• Radiation Oncology Journal
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• v.25 no.1
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• pp.34-42
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• 2007

[ $\underline{Purpose}$ ]: We performed a retrospective non-randomized clinical study of locally advanced rectal cancer, to evaluate the anal sphincter preservation rates, down staging rates and survival rates of preoperative chemoradiotherapy. $\underline{Materials\;and\;Methods}$: From January 2002 to December 2005, patients with pathologically confirmed rectal cancer with clinical stage T2 or higher, or patients with lymph node metastasis were enrolled in this study. A preoperative staging work-up was conducted in 36 patients. All patients were treated with preoperative chemoradiotherapy, and curative resection was performed for 26 patients at Hallym University Sacred Heart Hospital. Radiotherapy treatment planning was conducted with the use of planning CT for all patients. A total dose of $45.0{\sim}52.2\;Gy$ conventionally fractionated three-dimensional radiotherapy was delivered to the whole pelvis. Chemotherapy was given at the first and fifth week of radiation therapy with continuous infusion i.v. 5-FU (Fluorouracil) and LV (Leucovorine). Surgical resection was performed 2 to 4 weeks after the completion of the chemoradiotherapy regimen. $\underline{Results}$: The complete resection rate with negative resection margin was 100% (26/26). However, a pathologically complete response was not seen after curative resection. Surgery was done by LAR (low anterior resection) in 23 patients and APR (abdomino-perineal resection) in 3 patients. The sphincter preservation rate was 88.5% (23/26), down staging of the tumor occurred in 12 patients (46.2%) and down-sizing of the tumor occurred in 19 patients (73%). Local recurrence after surgical resection developed in 1 patient, and distant metastasis developed in 3 patients. The local recurrence free survival rate, distant metastasis free survival rate, and progression free survival rate were 96.7%, 87% and 83.1%, respectively. Treatment related toxicity was minimal except for one grade 3, one grade 4 anemia, one grade 3 leukopenia, and one grade 3 ileus. $\underline{Conclusion}$: Preoperative concurrent chmoradiotherapy for locally advanced rectal cancer seems to have some potential benefits: high sphincter preservation and down staging. Treatment related toxicity was minimal and a high compliance with treatment was seen in this study. Further long-term follow-up with a larger group of patients is required.