• Journal of the Korean Institute of Gas
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• v.12 no.3
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• pp.43-49
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• 2008

The evaporation heat transfer coefficient and pressure drop of R-22 and R-407C in horizontal copper tubes were investigated experimentally. The main components of therefrigerant loop are a receiver, a compressor, a mass flow meter, a condenser and a double pipe type evaporator (test section). The test section consists of a smooth copper tube of 4.3 mm and 6.4 mm inner diameter. The refrigerant mass fluxes were varied from 100 to $300[kg/m^2s]$ and the saturation temperature of evaporator were 5 [$^{\circ}C$]. The evaporation heat transfer coefficients of R-22 and R-407C rise with the increase in mass flux and vapor quality. The evaporation heat transfer coefficient of R-22 for inner diameter tube of 4.3 mm and 6.4 mm is about $7.3{\sim}47.1%$ and $5.68{\sim}46.6%$ higher than that of R-407C, respectively.

• Journal of Environmental Science International
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• v.9 no.3
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• pp.223-228
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• 2000

The purpose of this study is to evaluate the purification capacity of pollutants by column test with the tidal flat sediment. Sediment materials were taken from Chunjangdae tidal flat which located in Chungnam Seochungun. The column tests were conducted on four conditions(R1 : raw sewage filtered by G2 filter, R2 : sterilized sewage after filtered by GF/C filter, R3 : R2 /filtered(membrane) seawater (1:1), R4 : R2 /filtered(membrane) seawater(1:2)). The results of this study may be summarized as followed ; The removed COD by column tests were increased according to increasing the quantity of sewage. During the column tests of 580min, the total removed ammonia nitrogen were 90.1mg for R1, 81.0mg for R2, 27.6mg for R3 and 4.1mg for R4. The result was similar to COD experiment. During the 580min, the total removed total-phosphates were 3.4mg for R1, 4.2mg for R2, 5.6mg for R3 and 2.0mg for R4. The removal efficiency of Pb and Cd for R3 and R4 reactor were higher than R1 and R2 reactor. The remove of heavy metal by the column test was high in sample with seawater. But in the initial 20min, the adsorbed Pb and Cd showed about 3% of the total adsorbed Pb and Cd during 580min.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.28 no.11
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• pp.450-457
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• 2016

While many studies on the heat transfer effect of an impinging jet have been published, most studies focus on the downward impinging jet. This study investigates the impinging jet heat transfer phenomenon when water at a temperature of $24^{\circ}C$ impinges on the downward isothermal circular plate at 60, 70, and $80^{\circ}C$ and when the upward round jet nozzle is 4, 6, and 8 mm diameter with a flow rate 3.6, 4.6, and 5.6 L/min, respectively, and when the ratio of the nozzle clearance/nozzle diameter (H/D) is 1. The results showed that, as the nozzle diameter decreases, the heat transfer coefficient increases at a constant flow rate. The correlation equation of $Nu_r$, $Pr_r$, and $Re_{jg}$ is obtained in the impinging and constant velocity flow region $(Nu_r/Pr^{0.4}_r)Dr=4.6[Re_{jg}(r/R_c)Dr]^{0.8}$ at all flow rates, in the deceleration and falling flow regions $(Nu_r/Pr^{0.4}_r)Dr=42.7{\mid}Re_{jg}(r/R_c)Dr-345.7{\mid}^{0.3}$ at 3.6 L/min, $(Nu_r/Pr^{0.4}_r)Dr=92.4{\mid}Re_{jg}(r/R_c)Dr-16.8{\mid}^{0.2}$ at 4.6 L/min, and $(Nu_r/Pr^{0.4}_r)Dr=322.4{\mid}Re_{jg}(r/R_c)Dr-536.2{\mid}^{0.01}$ at 5.6 L/min.

• Journal of Korean Society of Water and Wastewater
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• v.21 no.5
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• pp.641-647
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• 2007

This study aims to find out optimum condition for hydrogen production and organic removal when treating food and swine wastewater together. For this purpose, various batch tests were conducted by changing mixture ratio from 6:4 (food wastewater:swine wastewater) to 1:9 without pretreatment process. For hydrogen production through anaerobic fermentation, the mixture ratios of R-1 (6:4), R-2 (5:5) and R-6 (1:9) were out of pH range appropriate for hydrogen production and mixture ratios of R-3 (4:6), R-4 (3:7), and R-5(2:8) showed appropriate hydrogen production where their pH ranges were 5.1~5.5. Especially in case of R-3, it consistently maintained appropriate pH range for hydrogen production for 72hr and produced maximum hydrogen. The characteristics of hydrogen production and cumulative hydrogen production according to each mixture ratio showed that R-1, R-2 and R-6 did not produce any hydrogen, and maximum hydrogen productions of R-3, R-4 and R-5 were 593ml, 419ml and 90ml, respectively. Total cumulative hydrogen productions of R-3, R-4 and R-5 were 1690ml, 425ml and 96ml, respectively. Based on previous results, it was concluded that, the most appropriate mixture ratio of food wastewater and swine wastewate rwas 4:6 (R-3). The experiment for COD removal rate to evaluate organic removal efficiency revealed that R-3, R-4 and R-5 showed high removal efficiencies during the highest hydrogen production amount and the highest efficiency was 41% with R-3.

• The Korean Journal of Ecology
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• v.27 no.3
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• pp.165-171
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• 2004

Weight loss and nutrients dynamics during decomposition of oak roots (diameter classes: R₁〈0.2㎝, 0.5㎝〈R₂〈1㎝, 1㎝〈R₃〈2㎝, 2㎝.〈R₄〈4㎝) (Quercus acutissima) were studied for 33-months in Kongiu, Korea. After 33-months, decomposition rate of R₁, R₂, R₃ and R₄ was 49.6%, 47.5%, 66.4% and 66.1%, respectively. The decomposition constant(k) for R₁, R₂, R₃, and R₄ was 0.249/yr, 0.234/yr, 0.397/yr and 0.393/yr, respectively. Larger diameter class of the root lost more weight than smaller diameter class. N concentration in decomposing oak roots increased in all diameter classes. After 33-months, remaining N in R₁, R₂, R₃ and R₄ was 66.5%, 80.7%, 84.4% and 44.4%, respectively. K concentration in decomposing oak roots decreased in early part of decomposition and then increased in later stage of decomposition. After 33-months, remaining P in R₁, R₂, R₃ and R₄ was 64.7%, 62.4%, 93.1% and 30.7%, respectively. K concentration in decomposing oak roots decreased rapidly in early stage of decomposition. Remaining K in R₁, R₂, R₃ and R₄ was 11.6%, 10.6%, 5.9% and 7.7%, respectively. Ca concentration in decomposing oak roots showed different among diameter classes. After 33-months, remaining Ca in R₁, R₂, R₃ and R₄ was 66.2%, 51.0%, 39.1% and 48.3%, respectively. Initial concentration of Mg in oak root was higher in smaller diameter class. After 33-months, remaining Mg in R₁, R₂, R₃ and R₄ was 15.3%, 29.9%, 24.5% and 69.4%, respectively.

• Journal of Chest Surgery
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• v.44 no.2
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• pp.154-158
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• 2011

Background: Video-assisted thoracic sympathicotomy plays an important for the treatment of essential hyperhidrosis. Patients are usually satisfied with the surgical outcome at the early post-operative period, but suffer recurrence and compensatory sweating in the late post-operative period. There are many sympathicotomy methods to minimize recurrence and compensatory sweating. We compared the outcome of sympathicotomy methods above the third rib (R3) and the fourth rib (R4) with regards to symptoms, satisfaction, recurrence, and compensatory palmar and axillary hyperhydrosis. Materials and Methods: From January 1999 to April 2009, 39 cases of thoracoscopic sympathicotomy at the third rib (R3), and 94 cases of thoracoscopic sympathicotomy at the fourth rib (R4) for palmar and axillary hyperhidrosis were compared for early and late post-operative satisfaction, compensatory sweating and recurrence. Results: There was no sex or age difference between groups. Early satisfaction was 94.9% and 98.9% in the R3 group and R4 group, respectively. There was no difference in early satisfaction (94.9% in R3 and 98.9% in R4), late satisfaction (84.6% in R3 and 89.4% in R4), or recurrence (17.9% in R3 and 17.0% in R4) between groups. There was significant difference in compensatory sweating (71.8% in R3 and 33% in R4, p=0.002). Conclusion: R4 sympathicotomy demonstrated superior efficacy in the treatment of compensatory sweating compared to R3 in palmar and/or axillary hyperhidrosis.

• Journal of the Korean Ceramic Society
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• v.38 no.5
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• pp.431-437
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• 2001

본 연구에서는 양이온 교환반응에 의해 Na-Mont와 R$_{11}$SO$_4$로부터 R$_{11}$SO$_4$-Mont 층간화합물을 합성한 후, 이 R$_{11}$SO$_4$-Mont 층간화합물을 다시 제 4차 유기 양이온인 (Et)$_4$N$^{+}$ 이온 및 (Bu)$_4$N$^{+}$ 이온과 반응시켜 그 거동을 살펴보았다. R$_{11}$SO$_4$-Mont를 (Et)$_4$N$^{+}$이온과 반응시켰을 대보다 (Bu)$_4$N$^{+}$ 이온과 반응시킨 경우에 좀 더 큰 층간거리가 얻어졌다. R$_{11}$SO$_4$-Mont를 (Et)$_4$N$^{+}$이온 및 (Bu)$_4$N$^{+}$과 반응시켜 얻은 층간화합물을 다시 아세토니트릴, 에탄올 및 디옥산과 팽윤반응을 수행한 결과 층간거리가 확장되었으나, 이는 Na-Mont를 R$_{11}$SO$_4$와 48시간 교환 반응시킨 후에 교환용액 하에서 얻은 R$_{11}$SO$_4$-Mont의 층간거리에 불과했다. 원소분석결과, R$_{11}$SO$_4$-Mont와 (Bu)$_4$N$^{+}$를 반응시킬 경우 반응이 반응식 b에 의거 진행되고, (Bu)$_4$N-Mont를 R$_{11}$SO$_4$와 반응시킬 경우에는 반응식 c에 의거 진행됨을 예측할 수 있었다.의거 진행됨을 예측할 수 있었다.

• Journal of Korean Society for Quality Management
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• v.47 no.4
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• pp.713-723
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• 2019

Purpose: The purpose of this study is to develop a statistical program for capability analysis of measuring system and measurement process based upon KS Q ISO 22514-7. Methods: R is a powerful open source functional programming language that provides high level graphics and interfaces to other languages. Therefore, in this study, we will develop the statistical program using R language. Results: The R program developed in this study consists of the following five modules. ① Measuring system capability analysis with Type 1 study data: MSCA_Type1.R ② Measuring system capability analysis with Linearity study(Type 4 study) data: MSCA_Type4.R ③ Measurement process capability analysis with Type 1 study & Gage R&R study data: MPCA_T1GRR.R ④ Measurement process capability analysis with Type 4 study & Gage R&R study data: MPCA_T4GRR.R ⑤ Attribute measurement processes capability analysis : AttributeMP.R Conclusion: KS Q ISO 22514-7 evaluates measuring systems and measurement processes on the basis of the measurement uncertainty that was determined according to the GUM(KS Q ISO/IEC Guide 98-3). KS Q ISO 22514-7 offers precise procedures, however, computations are more intensive. The R program of this study will help to evaluate the measurement process.

• Journal of the korean academy of Pediatric Dentistry
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• v.43 no.2
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• pp.137-144
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• 2016

The aim of this study was to evaluate the effect of a range of acidic pH values on the push-out bond strength and surface morphology of tricalcium silicate materials: Biodentine$^{(R)}$, Theracal$^{(R)}$ and ProRoot MTA$^{(R)}$. The standardized lumens of root slices prepared from extracted single-root human teeth were filled with Biodentine$^{(R)}$, Theracal$^{(R)}$ and ProRoot MTA$^{(R)}$ according to manufacturer's instructions. The specimens were randomly divided into 4 groups (n = 20) for each material and then incubated for 4 days at $37^{\circ}C$; 3 acidic groups (butyric acid buffered at pH 4.4, 5.4, 6.4) and 1 control group (phosphate buffered saline solution at pH 7.4). The push-out bond strengths were then measured by using a universal testing machine and the surface morphology of each experimental group was analyzed by a scanning electron microscope. Biodentine$^{(R)}$ and Theracal$^{(R)}$ showed higher push-out bond strength compared with ProRoot MTA$^{(R)}$ after exposure to acidic pH values. A substantial change in the surface morphology of each material occurred after exposure to different pH values. In conclusion, the push-out bond strengths of Biodentine$^{(R)}$ and Theracal$^{(R)}$ are higher than the ProRoot MTA$^{(R)}$. Further the acidic environment weakens the push-out bond strength and microstructure of tricalcium silicate materials.

• Bulletin of the Korean Mathematical Society
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• v.49 no.4
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• pp.885-898
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• 2012

Let m, n, r be nonzero fixed positive integers, R a 2-torsion free prime ring, Q its right Martindale quotient ring, and L a non-central Lie ideal of R. Let D : $R{\rightarrow}R$ be a skew derivation of R and $E(x)=D(x^{m+n+r})-D(x^m)x^{n+r}-x^mD(x^n)x^r-x^{m+n}D(x^r)$. We prove that if $E(x)=0$ for all $x{\in}L$, then D is a usual derivation of R or R satisfies $s_4(x_1,{\ldots},x_4)$, the standard identity of degree 4.