Travel, Code, and Engineering
on June 21, 2015 by Kurt Tomlinson
I'm planning a trip to Korea in about a month. An outbreak of MERS started a little over a month ago, so I became concerned that my trip might have to be cancelled. I researched the MERS outbreak in Korea, and I learned about epidemic (or epi) curves.
Epi curves are used by epidemiologists (those who study the patterns, causes, and effects of health and disease conditions in defined populations) to track epidemics. The horizontal axis of an epi curve is time, and the vertical axis is the number of cases confirmed on a particular day.
I found MERS epi curves for Korea on the WHO (World Health Organization) website. You can see the epi curve for Korea and China for June 19 below. The rectangle for May 19 looks a little strange because it shows that there were two newly confirmed cases in Korea and one newly confirmed case in China on that day.
As you can see, the number of MERS cases is declining. I imagine this epi curve is fairly typical for outbreaks of disease. It starts slowly as the index cases infects a few other individuals. There is then a rapid period of growth as the victims infected by the index case infect others. Next, awareness of the epidemic causes health care workers and the general public to take action to quarantine and treat the outbreak. After this, the number of cases slowly declines to zero. I hope Korea will be nearly MERS-free by the time I arrive.
In response to the MERS outbreak, Korea closed hospitals and schools. MERS did not spread outside of hospitals, so schools and kindergartens began reopening.
Photo by Tom Thai
on June 14, 2015 by Kurt Tomlinson
The first step in getting an F-1 student visa is to be accepted by an American school. This can be either a college/university, English-language program, or high school. The process for being accepted into one of these programs is dependent on the program.
Next, your school will give you an I-20 form. Once you have your I-20, you have to gather some other required documents:
Required documents for F-1 visa interview in South Korea
Additionally, there are some recommended documents that you can prepare to make your visa interview easier:
Be prepared to state clearly your educational goals; your major; why you chose that major; why that major is important to your future career in your home country; your graduate school plans, if any; how your degree will help you when you return home.
If you answer the interviewers questions to his/her satisfaction, they will inform you at the end of the interview if you will be receiving a visa or not. If they will not grant you a visa, they will tell you why. You can gather more evidence and schedule another visa interview later to try again. I think that if you fail two interviews that there is a mandatory waiting period of some time before you can have a third interview.
on May 31, 2015 by Kurt Tomlinson
There are a number of misconceptions about 2.4 GHz and 5 GHz Wi-Fi. Let's clear those up.
In the US, the FCC set aside the frequencies 2,400-2,483.5 MHz and 5,150-5,725 MHz for unlicensed broadcasts such as Wi-Fi, cordless phones, etc.* These regions are known as the 2.4 GHz and 5GHz bands, respectively.
The upper frequency of a band minus the lower frequency of a band is the "bandwidth". The bandwidth of a frequency band is directly proportional to the rate at which data can be transmitted. The bandwidth of the 2.4 GHz band is about 80 MHz and the bandwidth of the 5 GHz band is about 570 MHz. Therefore Wi-Fi can transmit data faster on the 5 GHz band because it is wider.
*The ranges given here aren't 100% accurate. The way the FCC splits up the electromagnetic spectrum is complicated.
Microwaves are a huge source of interference for Wi-Fi. Microwaves heat up food by showering it with 2.4 GHz radiation. Some of this radiation leaks out and confuses Wi-Fi receivers when the microwave is running. Cordless phones also often operate on the 2.4 GHz band. The 5 GHz band is used by fewer devices, so the amount of interference on it is less.
The radio engineer formula gives the path loss in db:
where L is the path loss in decibels, d is the distance traveled by the signal, f is the frequency of the signal, and c is the speed of light. Based on this equation, we can expect the path loss to be 20*log10(5/2.4) = 6.3752 dB more for a 5.0 GHZ signal than a 2.4 GHz.
Transmit a pair of signals at 2.4 GHz and 5.0 GHz with 100 mW of transmit power each. If the 2.4 GHz signal received is 10 mW, then the 5 GHz signal will only be 2.304 mW at the same receiver.
Photo by Bill Smith
on May 24, 2015 by Kurt Tomlinson
Living in the Philippines was a daily adventure. Even something as simple as going shopping presented new and interesting challenges. This is part two of a two-part series.
Credit cards were one of the things I missed most while living in the Philippines. Almost nowhere accepted credit cards except for the major stores in the local SM Supermall. Several restaurants and the local hospital also declined my to accept my credit card even though they had prominently displayed signs proclaiming that they accepted credit cards. When I asked about the signage, the only response I ever got was nervous laughter and a stare as they waited for me to find the cash.
Everything is smaller there. Cereal boxes are maybe 10 ounces. The largest soft drink at McDonald's could only be generously be called a small in America. And drinks at the supermarket are sold almost exclusively on an individual basis. There are no six-packs of beer or 12-packs of Coke. Cans and bottles are sold individually with relatively high per-unit prices. On the flip side, Red Horse, a very strong local beer, sold for 70 pesos per liter (about 3 cans of beer for less than $1.75) at any 7-Eleven. That's a deal not likely to be matched in America ever.
On Clark Air Base, duty-free stores were prolific. People often associate the words "duty-free" with bargains. After my experience with these stores I can assure you that is not the case. The prices in the stores are not good. However, these stores often offer imported products that cannot be obtained anywhere else. In that sense, "duty-free" stores would be more accurately described as foreign specialty stores. the only things you should buy their are items you can't get anywhere else. Their prices are, across the board, higher than standard stores.
Duty-free stores in the Clark Freeport Zone catered to Americans. They sold American goods and accepted American dollars. This is very convenient when you're reluctant to use a local ATM due to outrageous exchange and ATM usage fees. The catch is that the exchange rate offered at these duty free stores is often worse than what you'd get from your bank. The exchange rate was often around ₱41-42PHP/USD at these stores when the market rate was closer to ₱44-45PHP/USD. That's about a 7% fee compared with the 0-5% fees typically charged by American banks.
Although buying individual bottles/cans of drinks in stores was usually somewhat costly, I found vending machines to be very affordable. Compared to American vending machines where a can of soda runs about $1 USD and larger bottles go from $1.25-$2.50 USD depending on the brand, Filippino vending machines were a steal. A bottle of Gatorade was only ₱25 PHP or $0.56 USD, and vending machine coffee was about ₱12 PHP per cup. (The coffee quality wasn't great, but it worked in a pinch.) Although you still pay slightly more for the luxury of buying a single item, the ridiculous markup usually present on American vending machine items was nowhere to be found.
Want to read more about shopping in the Philippines? Check out the other part of this series:
Photo of Quiapo, Manila by shankar s.
on May 17, 2015 by Kurt Tomlinson
Living in the Philippines was a daily adventure. Even something as simple as going shopping presented new and interesting challenges. This is part one of a two-part series.
I'd never bartered before visiting the Philippines. It took me several months to become accustomed to the idea, but by the end of my rotation there I was able to negotiate some pretty good deals. Eventually I was even able to turn my biggest bartering weakness, being foreign, into an advantage.
Vendors in the Philippines see young white males like myself as walking bags of money. They're keenly aware of the naivety of young foreigners like myself and they try their best to take advantage of it. Prices for me, I came to find out eventually, were often initially set at double to triple the price that would be quoted to a local. Knowing this, my first counter offer, when unaware of the actual cost of the item in question, was half.
Oftentimes half the initially quoted price was still higher than I should have paid, but it was usually the lowest most vendors were willing to settle for. Maximizing the price they got from a foreigner was a mark of pride for them, so accepting a reasonable offer was akin to losing face. Knowing this, I'd offer to buy multiple or give the impression that my other foreign friends would also buy from the vendor if the price was lowered. Whether the future purchases materialized or not, my foreignness was often enough to convince the shop owner to accept my reasonable offer.
Taxis in Manila love to barter. About 50% of taxis will claim their meter is broken or refuse your fare if you request to use the meter. (This is actually somewhat reasonable as the meter starts at about 50 cents and goes up less than 1 dollar per mile, if I recall correctly. One day I took a trip across the city of Manila in rush hour traffic for less than $20.) The proportion of metered/bartered taxis depends on time of day, location, and your patience.
Airport taxis are the worst of the lot. At MNL, there are yellow metered taxis that come so slowly that you have to wait in line for hours in order to get one. Going to Malate from MNL, a trip of about 8km, I was quoted around $30 USD from the aggressive, non-metered taxi drivers waiting outside the terminal. I tried to barter with them, but none would go lower than about $24 USD. I walked away from the airport determined to snag a taxi on a surface street. As I walked, cabbies continued to accost me, and their prices steadily declined as I got further away from the terminal. Eventually I accepted one cabby's offer of ₱300 PHP or about $7 USD.
Photo of Bonifacio Global City by Roberto Verzo