• The Journal of Korean Society for Radiation Therapy
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• v.24 no.1
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• pp.31-37
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• 2012

Purpose: This study evaluated the usefulness of Helmet bolus device using Bolx-II, paraffin wax, solid thermoplastic material in total scalp irradiation. Materials and Methods: Using Rando phantom, we applied Bolx-II (Action Products, USA), paraffin wax (Densply, USA), solid thermoplastic material (Med-Tec, USA) on the whole scalp to make helmet bolus device. Computed tomography (GE, Ultra Light Speed16) images were acquired at 5 mm thickness. Then, we set up the optimum treatment plan and analyzed the variation in density of each bolus (Philips, Pinnacle). To evaluate the dose distribution, Dose-homogeneity index (DHI, $D_{90}/D_{10}$) and Conformity index (CI, $V_{95}/TV$) of Clinical Target Volume (CTV) using Dose-Volume Histogram (DVH) and $V_{20}$, $V_{30}$ of normal brain tissues. we assessed the efficiency of production process by measuring total time taken to produce. Thermoluminescent dosimeters (TLD) were used to verify the accuracy. Results: Density variation value of Bolx-II, paraffin wax, solid thermoplastic material turned out to be $0.952{\pm}0.13g/cm^3$, $0.842{\pm}0.17g/cm^3$, $0.908{\pm}0.24g/cm^3$, respectively. The DHI and CI of each helmet bolus device which used Bolx-II, paraffin wax, solid thermoplastic material were 0.89, 0.85, 0.77 and 0.86, 0.78, 0.74, respectively. The result of Bolx-II was the best. $V_{20}$ and $V_{30}$ of brain tissues were 11.50%, 10.80%, 10.07% and 7.62%, 7.40%, 7.31%, respectively. It took 30, 120, 90 minutes to produce. The measured TLD results were within ${\pm}7%$ of the planned values. Conclusion: The application of helmet bolus which used Bolx-II during total scalp irradiation not only improves homogeneity and conformity of Clinical Target Volume but also takes short time and the production method is simple. Thus, the helmet bolus which used Bolx-II is considered to be useful for the clinical trials.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.40 no.1
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• pp.29-36
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• 2004

This study deals with an analysis on the sinking resistance for the model purse seine, in the case of different netting material and sinkers. The experiment was carried out using rune simplified model seines of knotless nettings. Dimension of model seines 420cm for corkline and 85cm for seine depth, three groups of models rigged 25, 45 and 60g with the same weighted sinkers in water were used. These were named PP-25, PA-25, PES-25, PP-45, PA-45, PES-45, PP-60, PA-60 and PES-60 seine. The densitie($\rho$) of netting materials were 0.91g/cm$cm^3$, 1.14g/cm$cm^3$ and 1.38g/cm$m^3$. Experiments carried out in the observation channel in a flume tank under still water conditions. Sinking motion was recorded by the one set of TV-camera for VTR, and reading coordinate carried out by the video digitization system. Differential equations were derived from the conservation of momenta of the model purse seines and used to determine the sinking speeds of the depths of leadline and the other portions of the seines. An analysis carried out by simultaneous differential equations for numerical method by sub-routine Runge-Kutta-Gill The results obtained were as follows : 1. Average sinking speed of leadline for the model seines rigged 60g with the same weighted sinkers in water was fastest for 12.2cm/sec of PES seine, followed by 11.4cm/sec of PA and 10.7cm/sec of PP seines. 2. The coefficient of resistance for netting of seine was estimated to be $K_D=0.09(\frac{\rho}{\rho_w})^4$ 3. The coefficient of resistance for netting bundle of seine was estimated to be $C_R=0.91(\frac{\rho}{\rho_w})$ 4. In all seines, the calculated depths of leadline closely agreed with the measured ones, each 25g, 45g, 60g of weighted sinkers were put into formulas meas.=1.04cal., meas.=0.99cal. and meas.=0.98 cal.

• Journal of the Korean Institute of Telematics and Electronics
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• v.5 no.4
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• pp.36-40
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• 1968

새로운 반사형 텔레비젼 디스푸레이를 소개한다. 이 방법에서는 선상의 액체결정의 다이나믹 스캣터링 모오드(Dynamic Scattering Mode, DSM)를 이용하며 주위가 밝은 곳에서도 볼 수 있다. 6∼12μm 두께의 액체결정은 뜯을 수 있는 음극선관 위에 와이어-모자의 훼이스 프레이트를 사용하는 전자속으로 실시간에 번지선택된다. 두가지 종류의 액체결정물질-Anasyliden Para-Amino Phenyl Acetate(APAPA)와 RCA 특유의 실온액체결정-을 시험했는데 동작온도(APAPA는 82°∼110℃이고 다른 것은 실온)를 제외하고는 비슷한 결과가 나왔다. 사방 3.1cm의 디스푸레이에서는 해상도가 적용 텔레비젼에 필요한 150line 보다 약간 떨여졌는데 그 원인은 액정결정 때문이 아니고 모자익의 구조에 의한 제한 때문이다. 더 나은 해상도를 얻으려면 디스푸레이를 좀더 크게하면 된다. 콘트라스트는 최적화(7.5:1)하지 않았다. 그러나 이 값을 정적인 디스푸레이에서 본 바와 같이 15∼20대 1로 개선하기 위해서는 몇가지의 기술을 사용할 수 있다. 이 디스푸레이 방법의 매력으로는 적당한 외부조명하에서는 약 ±45°의 넓은 관람각을 갖는데 있다고 하겠다. 액체결정내에서 DSM이 일어나도록 하는데 필요한 전류, 전압치들을 보면 평평한 텔레비젼 화면에 적합한 완전한 번지선택법에의 근사방법이 발견될 수 있으리라는 희망을 갖일 수 있다.

• 한국정보디스플레이학회:학술대회논문집
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• 2005.07b
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• pp.892-896
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• 2005

In this paper, key issues of stainless steel foil substrates for display applications have been described. We studied and analyzed technical issues on substrate passivation/planarization to control surface roughness and capacitive coupling from conductive substrates. A thick (either multiple or single) passivation/planarization layer needs to be applied on the nonelectronic-grade stainless steel substrate to provide a smooth surface and electrical insulation from the conductive substrate. Especially for large size, high-resolution display applications, low k and thick passivation/planarization layers should be used for appropriate capacitive coupling. Based on our initial study, a unit area capacitance of less than $2nF/cm^2$ of passivation/planarization layers is needed for 32" HD TV OLED displays.

• Journal of radiological science and technology
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• v.27 no.1
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• pp.13-16
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• 2004

대장내시경검사는 역사적으로 돌아보면 원래 히포크라테스의 치루치료과정에서 직장경 사용으로부터 유래되며 그 후 Kelly의 25 cm 표준 S상 결장경의 발견으로 진전되었고 조명 및 각종 부속기구들이 많이 개선되면서 직장암의 발견에 기여해 왔다. 1911년에 독일 뮌헨의 Michael Hoffman이라는 광학 기술자가 프리즘을 여러 개를 연결하면 직선이 아닌 곡선에서도 빛을 그대로 전달할 수 있다는 사실을 발견하였고 이를 기초로 하여 1958년에 미국에서 Hirschowitz가 처음으로 섬유경(fiberscope)을 선보였고 그 이후 이용한 상부소화관에 대한 내시경 기술이 급속히 발전하기 시작하였고, 이를 기초로 1969년부터 ACMI, Olympus, Fujinon, Pentax 등 세계 유수의 내시경 회사들이 대장내시경을 제작하기 시작하였다. 1983년에 미국의 Welch-Allyn사가 CCD(Charge Coupled Device)라는 집광 장치를 만들어서 마치 내시경의 눈과 같은 작용을 해서 이것을 내시경 선단에 장치하고 전파를 이용하여 영상을 전달하여 이 상이 TV 모니터에 비치는 것을 보게 되는 전자내시경을 개발하여 현재는 상부내시경 뿐 아니라 대장내시경도 대부분이 전자 내시경으로 대체되어서 오늘에 이르고 있다.

• Journal of Radiation Protection and Research
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• v.40 no.1
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• pp.10-16
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• 2015

Bone changes are common sequela of irradiation in growing animal. The purpose of this study was to establish an experimental model of radiation-induced bone loss in growing mice using micro-computed tomography (${\mu}CT$). The extent of changes following 2 Gy gamma irradiation ($2Gy{\cdot}min^{-1}$) was studied at 4, 8 or 12 weeks after exposure. Mice that received 0.5, 1.0, 2.0 or 4.0 Gy of gamma-rays were examined 8 weeks after irradiation. Tibiae were analyzed using ${\mu}CT$. Serum alkaline phosphatase (ALP) and biomechanical properties were measured and the osteoclast surface was examined. A significant loss of trabecular bone in tibiae was evident 8 weeks after exposure. Measurements performed after irradiation showed a dose-related decrease in trabecular bone volume fraction (BV/TV) and bone mineral density (BMD), respectively. The best-fitting dose-response curves were linear-quadratic. Taking the controls into accounts, the lines of best fit were as follows: BV/TV (%) = $0.9584D^2-6.0168D+20.377$ ($r^2$ = 0.946, D = dose in Gy) and BMD ($mg{\cdot}cm^{-3}$) = $8.8115D^2-56.197D+194.41$ ($r^2$ = 0.999, D = dose in Gy). Body weight did not differ among the groups. No dose-dependent differences were apparent among the groups with regard to mechanical and anatomical properties of tibia, serum ALP and osteoclast activity. The findings provide the basis required for better understanding of the results that will be obtained in any further studies of radiation-induced bone responses.

• Journal of Korean Ophthalmic Optics Society
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• v.14 no.2
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• pp.9-14
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• 2009

Purpose: The purpose of this study was to examine the relationship between the accommodative facility, blink rate and accommodative lag according to the change of angles of main viewpoint of near distance worker and study an appropriate viewing angle that mitigates asthenopia, such as headaches or eye fatigue accompanied when reading and staring at the computer or TV for a long time. Methods: Total of 27 people including 12 male university students and 15 female university students in the age of 20 to 36 with frequent near distance works, such as computers, were selected to study the accommodative facility, the blink rate and the accommodative lag in accordance with the change of viewing angles of the near distance workers. The refraction error was corrected completely and the phoropter was shifted to near distance mode to locate the near distance indication at 40 cm. The accommodative facility and the blink rate were measured for one minute at each viewing direction of $40^{\circ}$ downward, $20^{\circ}$ downward, horizontal, and $20^{\circ}$ upward directions based on the horizontal line and the accommodative lag was measured in dynamic retinoscopy using retinoscope. Results: As a result, when the main viewpoint was moved on upper direction from the $40^{\circ}$ below, the accommodative facility was reduced and the blink rate and the accommodative lag were increased so their eyes became dry and the accommodation response was reduced. Conclusions: In near distance works, the eye fatigue level can be minimized by locating a book or a computer screen $40^{\circ}$ below than the horizontal direction.

• Journal of the Korean Society of Food Science and Nutrition
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• v.34 no.9
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• pp.1381-1387
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• 2005

This study was intended to evaluate the weight control program for 18 obese female college students during 9 weeks. The weight control program was composed of periodical counsel for self-control of dietary attitude and exercise with personal/group program. The female college students were average 21.3 years old and average 161.8 cm of height. The subjects were classified into 2 groups based on BMI: overweight group $25\le{BMI}<27$, obese group BMI$\ge$27. The subjects were average 71.56 kg of weight and $27.25 kg/m^2$ of BMI before they joined the program. The prompt of joining was less self-confidence for appearance. After 9 weeks, the overweight group lost their weight about 3.28 kg and also reduced 1.61 percentage of body fat. The obese group also lost their weight about 3.0 kg but reduced only 0.8 percentage of body fat. The serum levels of total cholesterol and LDL-cholesterol dropped significantly (p<0.05) in the overweight group. The $VO_2$ max inclosed 2.71 mL/kg/min in the overweight group. The obese group reduced caloric intakes from $109.2\%\;to\;86.5\%$ of RDA. The scores of dietary attitude such as eating speed, snack frequency, watching TV or reading during the eating were significantly increased (p<0.05) in obese group. These overall results suggest this program would be effective in self-weight control of overweight people. But the obese group assumed negative attitude in self-exercise program. So it is necessary to manage weight control programs, as considering obesity degree of subjects.

• Korean Journal of Soil Science and Fertilizer
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• v.45 no.4
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• pp.511-514
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• 2012

Polyethylene mulches have been used for weed control in vegetable production in Korea. One of the additional benefits associated with polyethylene mulches is soil warming. The objective of this study was to evaluate the effects of colored mulches on soil temperature change and Chinese cabbage yield. Mulch treatments were green (GV), black (BV), transparent (TV), and non-mulched (NM) soil. The highest soil-warming effect occurred under green mulch, and the lowest effect was found under black mulch. Daily mean values of soil temperature (10 cm depth) under GV were $2^{\circ}C$ higher than in NM soil. At midday (16:00), mean soil temperature was higher by $3.9^{\circ}C$ in GV, $3.1^{\circ}C$ in BV, and $2.1^{\circ}C$ in TV as compared to NM soil. At night (20:00-06:00), there was no significant difference in soil temperature among the treatments of different colored mulch, but soils in the mulch treatments were $2.4^{\circ}C$ higher as compared to NM soil. As compared with NM, the yield of Chinese cabbage under GV, BV, and TV were higher by 6.0, 26.0, and 12.0%, respectively.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.28 no.1
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• pp.10-18
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• 2017

In this paper, we designed and implemented a visible light identification(VLID) system consisting of a VLID reader and a tag which backscatters incident lights from the reader. A VLID tag sends its ID to the reader by switching an LCD shutter which is located on its surface. The VLID reader consists of six LEDs and a photodiode(PD). The LEDs emit visible light and a PD located in a center position of LEDs receives backscattered light from the VLID tag. A microcontroller and a commercial liquid crystal display(LCD) shutter for 3D-TV glasses are used to implement a VLID tag. Experiments were conducted to confirm VLID system performance. We successfully demonstrated experiments to send NRZ-OOK signal of 100 bps over a distance of 35 cm at daytime. Also, we suggested the theoretical maximum transmission rate and the various methods to enhance the separation distance between a VLID reader and a tag.