• 대한치과교정학회지
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• 제52권2호
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• pp.123-130
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• 2022

Objective: To evaluate if a remote digital monitoring system added at the end of orthodontic treatment could positively influence the retention phase by reducing the occurrence of misfit of removable appliances, number of emergency appointments (EA), and orthodontic relapse. Methods: Twenty-seven patients who completed active orthodontic treatment were divided into the study and control groups. In addition to the standard chairside follow-up appointments at month 1 (T1), month 3 (T2), month 6 (T3), the study group patients were monitored using Dental Monitoring^® with monthly intra-oral scans. Occurrence of misfit of removable retainers, number of EAs, and intercanine width change were recorded for both groups. Differences in EAs and retainer fit were assessed using the chi-square test. Intra-group and inter-group differences in the intercanine width were assessed with Friedman test and Mann-Whitney U test, respectively (α = 0.05). Results: The study group showed a significantly lower occurrence of misfit of removable retainers (p = 0.027) compared to the control group. No significant inter- and intra-group difference was found in the EAs and intercanine width change at each time-point. Conclusions: Integrating remote monitoring systems, such as Dental Monitoring^®, to the retention phase of the orthodontic treatment may lower the occurrence of misfit of removable retainers. However, a small sample size and a short observation period limit the strength of this evidence. These preliminary results tentatively suggest that remote monitoring technologies may be beneficial, especially during the COVID-19 pandemic, when the regularity of in-office visits might be disrupted.

• 한국의류학회지
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• 제36권8호
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• pp.875-884
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• 2012

Many Koreans have recently bleached their black hair to blond or a light color due to the influence of their favorite Korean idols. Bleaching effects were studied under various bleaching conditions, such as the concentration of oxidants, the ratio between bleach accelerant and oxidant, and treatment temperature and time. The degree of damage of bleached hair with the same color difference (${\Delta}E$) intervals was observed in SEM images, the retention of breaking load and the change of color after dyeing. The ratio between bleach accelerant and oxidant of 1:2.5 was an effective condition. $L^*$ values of the bleached hair treated with 9% oxidant increased to 90 min. At a treatment temperature of $30^{\circ}C$, $a^*$ values were maximum at 30 min and then decreased as time further increased; however, $b^*$ values of the bleached hair increased as the treatment time increased. At $45^{\circ}C$, both of $a^*$ and $b^*$ values showed a maximum at a specific time. Bleaching efficiency was influenced most by temperature, followed in order by time, and oxidant concentration. As the treatment time increased, $L^*$ values greatly increased with twice treatment; however, $a^*$ and $b^*$ values decreased. Bleached hair, which had a color difference of higher than 30, showed the scales were completely removed and the retention of the breaking load greatly decreased. Highly bleached hair showed a great decrease in $L^*$ values by dyeing; however, dyeing with bright colors was more indicative to the effect of bleaching.

• 한국조리학회지
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• 제18권4호
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• pp.266-276
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• 2012

본 연구는 이스트의 소금 스트레스 시간이 반죽의 발효와 제품의 특성에 미치는 결과를 분석하여 산업적으로 이용하고자 이루어졌다. 반죽의 가스 생성율과 발효율, pH, 부피, 비용적, TPA, crumScan, 색도와 관능검사 등을 통하여 분석하였다. 반죽의 가스 생성율과 발효율을 살펴본 결과 침지시간이 45분일 때 가장 가스 보유력이 좋은 것으로 나타났고, 침지시간이 15분, 30분, 45분의 pH 값이 5.74로 빵을 만들기에 가장 적절한 값이었다. 부피와 비용적은 45분이 가장 좋았으며, 조직감 분석결과 대조구의 경도가 가장 낮고 부드러웠으며, 탄력성은 크게 차이가 없었다. CrumScan결과 기공의 조밀도는 대조구가 가장 낮았으며, 기공의 찌그러짐 정도는 45분이 가장적었다. 색도 분석 결과는 L값은 75분, a값과 b값은 15분이 가장 높았다. 관능검사에서는 질감, 향, 식감, 맛에서 가장 기호도가 높은 침지시간 45분이 전체적인 기호도에서도 역시 가장 선호되었다.

• Asian-Australasian Journal of Animal Sciences
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• 제2권3호
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• pp.289-291
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• 1989

• 한국심리학회지:학교
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• 제18권1호
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• pp.31-48
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• 2021

본 연구는 특정 학과에 입학한 대학 신입생들의 학과 내 교우관계가 향후 해당 학과에서의 학업유지를 예측할 수 있는지를 확인하기 위해 수행되었다. 학업유지 상태는 측정한 기간 동안 학생이 대학에 등록을 하여 재적하고 있는 상태를 의미한다. 본 연구는 교우관계를 측정하기 위해 자신과 타인의 지각을 집단에서 파악할 수 있는 사회연결망 분석 방법을 사용하여 관계를 정량화하는 방법으로 사회적 요인을 구체화하였다. 본 연구의 참여자는 2017년, 2018년, 2019년 신입생을 대상으로 하였다. 이름 생성기 방식을 통하여 교우관계를 양적으로 나타내는 네트워크 변인들을 조사하였고 이를 독립변인으로 하여 2020년 1학기까지의 학업 중단 경험 유무를 통해 학업유지 정도를 예측하였다. 분석 방법은 Cox 비례위험모형 분석을 사용하였으며 결과는 내향 연결정도 중심성이 학생들의 학업유지를 유의하게 예측하는 것으로 나타났다. 본 연구의 결과는 학과 동기 사이의 교우관계가 학업유지 및 중단을 예측하여 조기선별과 학업유지를 위한 개입에 도움을 줄 수 있는 결과를 보여주었다는 점에서 의의가 있다. 다만 연구대상이 하나의 학과 신입생으로 제한되기 때문에 일반화를 하는데 한계가 있으므로 추가 연구가 필요할 것으로 생각된다.

• 한국환경보건학회지
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• 제25권3호
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• pp.29-35
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• 1999

Quantity and composition of biogas from semi-continuous anaerobic digestion of straw were obtained experimentally in laboratory scale digesters fed with 1 liter of 5% straw-water mixture and maintained at 35$^{\circ}C$. Experiments were carried out for hydraulic retention time(HRT) of 8, 10 and 15days, respectively. The amount and composition of biogas produced were measured until steady-state was achieved for each run. The amount of biogas and methane percent go through a maximum and decrease continuously towards the steady-state after three times operation of hydraulic retention time(HRT). Methane gas production rates at steady-state increase with the increasing of HRT. Biogas production of 0.45 liter/day with 25% methane, 0.42 liter/day with 33.7% methane and 0.492 liter/day with 31.7% methane were obtained for 8, 10 and 15days of HRT, respectively. The high proportion of soluble carbohydrates present in straw makes the volatile fatty acids to build up within the digester causing a drop in pH that inhibits digestion. Regular control of pH is therefore necessary by adding alkalinity. Reductions in COD increase with increase in HRT. The stratification of plant material within the digester is different from that of manure, and modifications in design and operation of digesters may be necessary if they are fed with plant matter.

• JSTS:Journal of Semiconductor Technology and Science
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• 제1권1호
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• pp.40-49
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• 2001

We have developed a repeatable process of forming uniform, small-size and high-density self-assembled Si nano-crystals. The Si nano-crystals were fabricated in a conventional LPCVD (low pressure chemical vapor deposition) reactor at $620^{\circ}c$ for 15 sec. The nano-crystals were spherical shaped with about 4.5 nm in diameter and density of $5{\times}l0^{11}/$\textrm{cm}^2$. More uniform dots were fabricated on nitride film than on oxide film. To take advantage of the above-mentioned characteristics of nitride film while keeping the high interface quality between the tunneling dielectrics and the Si substrate, nitride-oxide tunneling dielectrics is proposed in n-channel device. For the first time, the single electron effect at room temperature, which shows a saturation of threshold voltage in a range of gate voltages with a periodicity of ${\Delta}Ｖ_{GS}\;{\approx}\;1.7{\;}V$, corresponding to single and multiple electron storage is reported. The feasibility of p-channel nano-crystal memory with thin oxide in direct tunneling regime is demonstrated. The programming mechanisms of p-channel nano-crystal memory were investigated by charge separation technique. For small gate programming voltage, hole tunneling component from inversion layer is dominant. However, valence band electron tunneling component from the valence band in the nano-crystal becomes dominant for large gate voltage. Finally, the comparison of retention between programmed holes and electrons shows that holes have longer retention time.

• 상하수도학회지
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• 제18권5호
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• pp.580-587
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• 2004

The objective of this research is to investigate the electrochemical oxidation process for nitrogen removal in wastewater involving chloride ion and nitrogen compounds. The process experiment of electrochemical oxidation was conducted by using the stainless steel tube type reactor and the $Ti/IrO_2$ as anode. Free chlorine production and current efficiency variation for total nitrogen removal was compared depending on whether electrolyte is added, and the nitrogen type distribution under an operating condition. When chloride was added as electrolyte, it was found that production of free chlorine increased and the concentration of the chloride decreased as retention time passed. The concentration of chloride in influent decreased from 1,660 to 1,198 mg/L at the current density of $6.7A/dm^2$, while concentration of free chlorine increased to 132 mg/L. Current efficiency in removal of ammonium nitrogen was increased when chloride was dosed as electrolyte. It was observed that ammonium nitrogen was oxidized to nitrite and nitrate through electrochemical oxidation and that the concentration of total nitrogen in influent was reduced from 22.58 to 4.00 mg/L at the short retention time of 168 seconds through the electrochemical oxidation of nitrogen.

• 한국지하수토양환경학회지:지하수토양환경
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• 제22권1호
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• pp.13-17
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• 2017

Over 30% of domestic soil contamination has occurred via petroleum products and complex oil. Moreover, contamination by complex oil is more intense than it is by a single petroleum product species. In this study, we analyzed sectional TPH (total petroleum hydrocarbon) pattern and sectional ratio of current domestically distributed petroleum products, such as kerosene, diesel, bunker C, and lubricant and complex oils, to determine pollution characteristics of the soil. In the TPH pattern, kerosene, which is a light distillate, had an early retention time, and lubricant oil, which is a heavy distillate, had a late retention time in the gas chromatogram. In addition, we obtained a complexly contaminated soil via diesel and lubricant oil from the Navy and inspected it for its ratio of complex oil species. The inspection results showed that this soil was contaminated with 85% diesel and 15% lubricant oil. The method developed in this study could be used to determine complex petroleum sources and ratios at sites with accidentally contaminated soil.

• 한국물환경학회지
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• 제16권4호
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• pp.523-532
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• 2000

The purpose of this study was to investigate the effects of the hydraulic retention time (HRT) and organic loading rate (OLR) on microbial characteristics and treatment efficiency in sewage treatment using aerated submerged biological filter (ASBF) reactor. This reactor combines biodegradation of organic substrates by fixed biomass with a physical separation of biomass by filtration in a single reactor. Both simulated wastewater and domestic wastewater were used as feed solutions. The experimental conditions were a temperature of 17 to $27^{\circ}C$, a hydraulic retention time of 1 to 9hr, an organic loading rate of 0.47 to $3.84kg\;BOD/m^3{\cdot}day$ in ASBF reactor. This equipment could obtain a stable effluent quality in spite of high variation of influent loading rate. Total biomass concentration. biofilm thickness and biofilm mass increased an exponential function according to the increasing OLR. The relationships between water content and biofilm density were in inverse proportion. The percentage of backwash water to influent flow was almost 9%. The separation efficiency of biomass was the percentage of 91 to 92 in ASBF reactor. The sludge production rates in feed solutions of simulated wastewater and domestic wastewater were 0.14~0.26 kg VSS/kg BODrem, 0.43~0.48 kg VSS/kg BODrem, respectively.